Lactobacillus acidophilusis a "friendly" strain of bacteria used to make yogurt and cheese. Although we are born without it, acidophilus soon establishes itself in our intestines and helps prevent intestinal infections. Acidophilus also flourishes in the vagina, where it protects women against yeast infections.
Acidophilus is one of several microbes known collectively as probiotics(literally, "pro life," indicating that they are bacteria and yeasts that help rather than harm). Others include the bacteria L. bulgaricus, L. reuteri, L. plantarum, L. casei, B. bifidus, S. salivarius, and S. thermophilusand the yeast Saccharomyces boulardii. Your digestive tract is like a rain forest ecosystem with billions of bacteria and yeasts rather than trees, frogs, and leopards. Some of these internal inhabitants are more helpful to your body than others. Acidophilus and related probiotics not only help the digestive tract function, they also reduce the presence of less healthful organisms by competing with them for the limited space available. For this reason, use of probiotics can help prevent infectious diarrhea.
Antibiotics can disturb the balance of your "inner rain forest" by killing friendly bacteria. When this happens, harmful bacteria and yeasts can move in and flourish. This can lead to vaginal yeast infections. Conversely, it appears that the regular use of probiotics can help prevent vaginal infections and generally improve the health of the gastrointestinal system. Whenever you take antibiotics, you should probably take probiotics as well and continue them for some time after you are done with the course of treatment.
According to several studies, it appears that regular use of acidophilus and other probiotics can help prevent "traveler's diarrhea" (an illness caused by eating contaminated food, usually in developing countries). 4,12 1 One double-blind, placebo-controlled study followed 820 people traveling to southern Turkey, and found that use of Lactobacillus GGsignificantly protected against intestinal infection. 7 2 Other studies using S. boulardiihave found similar benefits, 11,13,14 3 including a double-blind, placebo-controlled trial enrolling 3,000 Austrian travelers. 14 4 The greatest benefits were seen in travelers who visited North Africa and Turkey. The researchers noted that the benefit depended on consistent use of the product, and that a dosage of 1,000 mg daily was more effective than 250 mg daily.
Probiotics may also help prevent or treat acute infectious diarrhea in children and adults.
A review of the literature published in 2001 found 13 double-blind, placebo-controlled trials on the use of probiotics for acute infectious diarrhea in infants and children; 10 of these trials involved treatment and 3 involved prevention. 71 5 Overall, the evidence suggests that probiotics can significantly reduce the duration of diarrhea and perhaps help prevent it. The evidence is strongest for the probiotic Lactobacillus GGand for infection with a particular virus called rotavirus, which causes severe diarrhea in children.
For example, one double-blind, placebo-controlled trial of 269 children (ages 1 month to 3 years) with acute diarrhea found that those treated with Lactobacillus GGrecovered more quickly than those given placebo. 22 6 The best results were seen among children with rotavirus infection. Similar results with Lactobacillus GGwere seen in a double-blind study of 71 children. 59 7 However, 224 young Chinese children with severe, acute diarrhea found no benefit from lactose-free formula supplemented with Bifidobacteriaand S. thermophilus, suggesting that probiotics may not be as useful for cases of severe, dehydrating diarrhea. 170 8 Also, Lactobacillus rhamnosusGG is not always associated with improvement. When given for 10 days to 229 infants from rural India hospitalized with acute diarrhea it did not reduce the severity of the diarrhea during that time period. 198 9 In addition, a double-blind study evaluated the possible benefits of the probiotic L. reuteriin 66 children with rotavirus diarrhea. 5 10 The study found that treatment shortened the duration of symptoms, and the higher the dose, the better the effect. Similar benefits were seen in a placebo-controlled trial of 151 infants and children given the probiotic Escherichia coliNissle 1917 (a safe strain of E. coli) for 21 days for nonspecific (presumably viral) cases of mild to moderate diarrhea. 181 11 A double-blind, placebo-controlled study of 81 hospitalized children found that treatment with Lactobacillus GGreduced the risk of developing diarrhea, particularly rotavirus infection. 61 12 A double-blind, placebo-controlled study found that Lactobacillus GGhelped prevent diarrhea in 204 undernourished children. 62 13 Other studies, though not entirely consistent, generally indicate that the probiotics B. bifidum, Streptococcus thermophilus, L. casei, Lactobacillus LB, and S. boulardii—both individually and combined with L. reuteriand L. rhamnosus—may also help prevent or treat diarrhea in infants and children. 8,9,11,15,23,26,56,57,92-93,108-109,150,183 14 One study found that bacteria in the B. bifidumfamily can kill numerous bacteria that cause diarrhea. 69 15 Keep in mind that diarrhea in young children can be serious. If it persists for more than a day, consult a physician.
A large (211-participant), double-blind, placebo-controlled study found that adults with diarrhea can benefit from probiotic treatment as well. 26 16 Another study found that regular use of probiotics could help prevent gastrointestinal infections in adults. 110 17
The results of many, but not all, double-blind and open trials suggest that probiotics, especially S. boulardiiand Lactobacillus GG, may help prevent or treat antibiotic-related diarrhea. 10,11,16 18,25 28,75,76,94-95, 97-98,143,183 For example, one study evaluated 180 people, who received either placebo or 1,000 mg of saccharomyces daily along with their antibiotic treatment, and found that the treated group developed diarrhea significantly less often. 16 19 A similar study of 193 people also found benefit. 18 20 And, at least 3 additional studies involving adults found that various species of Lactobacillus, taken either alone in combination, to be beneficial, 174,207 21 even in cases of Clostridium difficile, the most serious cause of antibiotic-induced diarrhea. 208 22 However, a study of 302 people found no benefit with Lactobacillus GG. 25 23 And, a review of four probiotic studies found insufficient evidence for their effectiveness in the treatment of Clostridium difficile, the most serious cause of antibiotic-induced diarrhea. 159 24 Although taking probiotic organisms in the proper concentration may be beneficial for antibiotic-induced diarrhea, at least one study found that consuming fresh yogurt during antibiotic treatments had no significant effect on the incidence of diarrhea. 160 25
Note:Diarrhea that occurs in the context of antibiotics may be dangerous; for this reason, physician consultation is essential.
Two double-blind, placebo-controlled studies enrolling a total of almost 700 people undergoing radiation therapy for cancer found that use of probiotics significantly improved radiation-induced diarrhea. 79,136 26 Similar evidence supports the use of Lactobacillus rhamnosus, 153 27 as well as a special, nonpathogenic form of E. coli. 78 28 However, of 85 women receiving pelvic radiation for cervical or uterine cancer, those who consumed a liquid yogurt preparation enriched with Lactobacillus caseihad no less diarrhea than those who took a placebo drink. 161 29 Small double-blind studies suggest S. boulardiimight be helpful for treating chronic diarrhea in people with HIV, hospitalized patients being tube-fed, and people with Crohn's disease. 11,19 21 30 Premature infants weighing less than 2,500 grams (5.5 pounds) are at risk for a life-threatening intestinal condition called necrotizing enterocolitis (NEC). In a study that pooled the results of 9 randomized, placebo-controlled trials involving 1,425 infants, probiotic supplementation significantly reduced the occurrence of NEC and death associated with it. 177 31 And, a subsequent study found similar benefits in very low birth weight infants weighing less than 1,500 grams (3.3 pounds). 189 32
The conditions Crohn’s disease and ulcerative colitis fall into the family of conditions known as inflammatory bowel disease. Chronic diarrhea is a common feature of these conditions.
A double-blind trial of 116 people with ulcerative colitis compared probiotic treatment against a relatively low dose of the standard drug mesalazine. 37 33 The results suggest that probiotic treatment might be equally effective as low-dose mesalazine for controlling symptoms and maintaining remission. Evidence of benefit was seen in other trials as well. 38,82,112 34 One preliminary study found S. boulardiihelpful for mild diarrhea in stable Crohn’s disease. 20 35 However, two studies failed to find benefit with Lactobacillusprobiotics, 113-114 36 and in an analysis of 8 randomized, placebo-controlled studies, probiotics were ineffective at maintaining remission in Crohn’s disease patients. 165 37 Probiotics might be useful for people with ulcerative colitis who have had part or all of the colon removed. Such people frequently develop a complication called pouchitis, inflammation of part of the remaining intestine. A 9-month, double-blind trial of 40 people found that a combination of three probiotic bacteria could significantly reduce the risk of a pouchitis flare-up in people with chronic pouchitis. 39 38 Participants were given either placebo or a mixture of various probiotics, including four strains of Lactobacilli, three strains of Bifidobacteria, and one strain of Streptococcus salivarius. The results showed that treated people were far less likely to have relapses of pouchitis. Another study found that probiotics used right after surgery can help prevent pouchitis from developing at all. 80 39 One study, however, failed to find benefit with Lactobacillus johnsoniiin people with Crohn’s disease who have undergone a similar operation. 129 40 Finally, some evidence hints that probiotics might reduce the joint pain that commonly occurs in people with either kind of inflammatory bowel disease. 115 41
People with irritable bowel syndrome (IBS) experience crampy digestive pain as well as alternating diarrhea and constipation and other symptoms. Although the cause of irritable bowel syndrome is not known, one possibility is a disturbance in healthy intestinal bacteria. Based on this theory, probiotics have been tried as a treatment for IBS, with some success.
For example, in a 6-week double-blind, placebo-controlled trial of 274 people with constipation-predominant irritable bowel syndrome, use of a probiotic formula containing Bifidobacterium animalissignificantly reduced discomfort and increased stool frequency. 144 42 And, 266 women with constipation who consumed yogurt containing Bifidobacterium animalisand the prebiotic fructo-oligosaccharides twice daily for two weeks experienced significant improvement compared to women consuming regular yogurt as a placebo. 182 43 Finally, in another trial of 298 IBS patients, 8 weeks of treatment with beneficial Escherichia colireduced typical symptoms compared to placebo. 200 44 Benefits were seen in 8 other small, double-blind trials as well, using L. plantarum, 2,53,70 45 L. acidophilus, 3,163 46 L. rhamnosus, 130 47 L. salivarusand Bifidobacterium, 116,188 48 as well as proprietary probiotic combinations including various strains. 54,117,156,187 49 Benefits have also been seen with combination prebiotic /probiotic formulas 118, 199 50 and prebiotics alone. 197 51 Of course, other studies have failed to find probiotics more effective than placebo. 68,119,172 52 Two studies that pooled previous randomized trials on the use of probiotics for IBS came to similar conclusions: probiotics appear to offer some benefit, most notably for global symptoms and abdominal discomfort. However, these two studies were unable to determine which probiotic species were most effective. 178,179 53
Use of probiotics during pregnancy and after childbirth may reduce risk of childhood eczema . In a very large, long-term, double-blind study, 1,223 pregnant women were given either placebo or a probiotic mixture (containing Lactobacilliand Bifidobacteria) beginning 2-4 weeks before delivery. 125 54 Their newborn children then received either probiotics or placebo for six months. The results showed that the probiotics mixture markedly reduced the incidence of eczema (though not of other allergic diseases). However, in a follow-up to this study, researchers found that the probiotic supplementation was not associated with reduced eczema in children followed through age 5. The probiotics also had no effect on allergic rhinitis or asthma. 193 55 Another study also yielded marginal results, 139 56 and a third study involving only lactobacillus found no benefit at all for the prevention of eczema. This latter study actually demonstrated a modestly increased the risk of wheezing bronchitis in infants who took the probiotic. 168 57 But, some probiotics combined with prebiotics may help to reduce wheezing in infants with eczema. For example, Bifidobacterium breveand a galacto-/fructo-oligosaccharide mixture (Immunofortis) showed benefit in one randomized study involving 90 infants. 206 58
Bifidobacterium longumand Lactobacillus rhamnosussupplementation did not reduce incidence of eczema atopic dermatitis or allergic sensitization at 12 months among Asian infants at risk of allergic diseases. 196 59 Researchers in another study concluded that not all probiotics are created equal. In this placebo-controlled study involving pregnant women and their infants, Lactobacillus rhamnosusreduced the incidence of eczema in the children, but a strain of Bifidobacterium animalisdid not. 186 60 According to some but not all studies, infants who already have eczema may benefit from probiotics. 30,51,52,77,120-121,128,154,166 61 However, a careful review of 12 studies involving a total of 781 children found no convincing evidence that probiotics can effectively treat eczema in this age group. 191 62 If probiotics are beneficial for childhood eczema, they are probably more effective at preventing the condition rather than treating it. A carefully conducted review of numerous studies cautiously concluded that probiotics may help reduce the risk of eczema in infants and children, particularly those at high risk. 154 63 And two subsequent reviews found that probiotics were more effective at preventing childhood eczema, particularly when given both to mother (before birth) and infant. 166,173 64
A number of studies suggest that various probiotics can enhance immune function . One 12-week, double-blind, placebo-controlled trial evaluated 25 healthy elderly people, half of whom were given milk containing a particular strain of Bifidobacterium lactis, the others milk alone. 42 65 The results showed various changes in immune parameters which the researchers took as possibly indicating improved immune function. Another double-blind, placebo-controlled study of 50 people using B. lactishad similar results. 41 66 A 7-month, double-blind, placebo-controlled study of 571 children in daycare centers in Finland found that use of milk fortified with Lactobacillus GGreduced the number and severity of respiratory infections. 43 67 In another controlled trial, probiotics ( Lactobacillus rhamnosus GGand Bifidobacterium lactisBb-12) given daily to infants in their formula significantly reduced the risk of acute otitis media and recurrent respiratory infections during the first year of life compared to placebo. 192 68 Benefits were seen in three other large studies, in which probiotics combined with multivitamins and minerals helped prevent colds (or reduce their duration and severity) in adults. 122-124 69 70 However, a smaller and shorter study failed to find any effect on respiratory infections. 81 71 Similarly, Lactobacillus fermentumgiven to 20 healthy elite distance runners over a 4-month period during winter training was significantly more effective at reducing the number and severity of respiratory symptoms compared with a placebo. 164 72 One study found that Lactobacillus GGor L. acidophilusmay improve the immune response to vaccinations. 83 73
An 8-week, double-blind, placebo-controlled trial of 70 overweight people found that a probiotic treatment containing S. thermophilusand Enterococcus faeciumcould reduce LDL ("bad") cholesterol by about 8%. 45 74 Similarly positive results were seen in other short-term trials of various probiotics. 44,46,73,74,100-101 75 However, a 6-month, double-blind, placebo-controlled trial found no long-term benefit. 72 76 Researchers speculate that participants stopped using the product regularly toward the later parts of the study.
The addition of the probiotic Lactobacillus rhamnosusto regular was no better than than placebo in 77 patients with chronic rhinosinusitis. 201 77
Probiotics may occasionally cause a temporary increase in digestive gas. But, beyond that, they do not present any known risks for most people. In one trial of 140 healthy infants, formula supplemented with long-chain polyunsaturated fatty acids and probiotics appeared as safe as standard formula, and did not have any effect on infant growth by the end of the 7-month trial. 194 1 However, individuals who are immunosuppressed could conceivably be at risk for developing a dangerous infection with the probiotic organism itself; at least one person taking immunosuppressive medications has died in this manner. 31 2 In a detailed review of four studies, researchers concluded that the use probiotics did not benefit patients with severe acute pancreatitis. 184 3 Furthermore, according to one study, the use of probiotics led to an increased risk of mortality in patients with severe acute pancreatitis, and should, therefore, be avoided under these circumstances. 1 4
Some probiotic supplements also contain prebiotics like FOS to "feed" the good bacteria. FOS appear to be generally safe. However, they can cause bloating, flatulence, and intestinal discomfort, especially when taken at doses of 15 g or higher daily. People with lactose intolerance may particularly suffer from these side effects.
Evidence from many but not all double-blind, placebo-controlled trials suggests that probiotics may be helpful for many types of diarrhea , as well as for irritable bowel syndrome . 2 28,53-57,68,70,71,130,144,156,157,171 1 Additionally, probiotics have shown some promise for preventing or treating eczema . 29,30,51,52, 125, 126,139,203,205 2 Probiotics may be helpful for controlling symptoms and maintaining remission in ulcerative colitis . 37-39,82,204 3 However, probiotics may be less useful for inducingremission; when probiotics were added to standard medications used for induction of remission, no additional benefits were seen in a study of people with mild-to-moderate ulcerative colitis. 155 4 Probiotics might help prevent colds , 43 5 possibly by improving immunity . 40-42,83,164 6 On a related note, one small, double-blind study found evidence that use of the probiotic bacteria Lactobacillus fermentumimproved the effectiveness of the influenza vaccine. 135 7 (The probiotic supplement was taken in two doses. One was taken two weeks before the vaccine, and the other was taken two weeks after.)
Although probiotics are widely used to prevent or treat vaginal yeast ( Candida albicans) infections, evidence regarding potential benefit remains incomplete and inconsistent. 31-36,48,84-85 8 A small trial of 55 women with vulvovaginal candidiasis did demonstrate that daily Lactobacillus rhamnosusand L. reuterisupplementation for 4 weeks combined with single dose fluconazole (an anti-fungal medication) decreased symptoms compared to fluconazole alone. 202 9 Another large, well-designed trial, however, failed to find a Lactobacilluspreparation helpful for preventing yeast infections caused by antibiotics. 86 10 One study did find that probiotics might reduce levels of Candida albicansin the mouth. 132 11 The bacteria Gardnerella vaginaliscan cause a different type of vaginal infection; as with vaginal yeast infections, probiotics have shown some promise for this condition, but evidence remains inconclusive. 145,158,175,190 12 A trial of 64 women taking a single dose of tinidazole for bacterial vaginosis suggests that women who also took daily probiotics capsules had better cure rates at 4 weeks. 195 13 The bacteria Helicobacter pyloriis the main cause of ulcers in the stomach and duodenum. Antibiotics can kill H. pylori, but more than one must be used at the same time, and, even then, the bacteria is not necessarily eradicated. Probiotics may be helpful. Evidence suggests that various probiotics can inhibit the growth of H. pylori. 65-67,87,169 14 While this effect does not appear to be strong enough for probiotic treatment to eradicate H. pylorion its own, preliminary evidence, including several small double-blind trials, suggest that various probiotics may help standard antibiotic therapy work better, reducing side effects and possibly increasing rate of eradication. 47,55,58,60,63,65,67,87,88, 97,98,131,148,149,162,185 15 Some, but not, all preliminary double-blind trials suggest that probiotics might improve cholesterol profile. 44-46,100-101,137 16 In addition, milk fermented by probiotics may slightly improve blood pressure levels. 104-106 17 18 Various probiotics might be helpful for allergic rhinitis (hay fever). 102-103,142 19 While there is some evidence that probiotics can help reduce symptoms of milk allergies, 49 20 one study found that adding probiotics to infant cow’s milk formula was not helpful. 176 21 One interesting study found that the use of probiotics during pregnancy and breastfeeding may decrease the likelihood that a highly allergic mother will pass her allergic tendencies to her breastfed infant. 180 22 One double-blind, placebo-controlled study of 70 people with chronic constipation found some evidence of benefit with Lactobacillus casei Shirota. 89 23 Another study found that Lactobacillus rhamnosuswas helpful for chronic constipation in children. 141 24 A small trial also found benefits in children, this time with a mixture of bifidobacteriaand lactobacilli. 151 25 In another study, a combination of B. lactisand B. longusshowed promise for improving bowel regularity in nursing home residents. 146 26 Finally, in a 6-week double-blind, placebo-controlled trial of 274 people with constipation-predominant irritable bowel syndrome, use of a probiotic formula containing B. animalissignificantly improved stool frequency. 144 27 A preliminary double-blind, placebo-controlled study found evidence that Lactobacillus GGmight potentially be helpful for treating antibiotic-resistant bacteria. 138 28 This small study followed 23 people with severe kidney disease who tested positive for vancomycin-resistant bacteria in the stool. (Vancomycin is one of the main “last-ditch” antibiotics for treatment of resistant bacteria.) Use of a yogurt product containing L. rhamnosusappeared to be more effective at ridding the gastrointestinal tract of these bacteria than placebo. However, the study suffered from a number of flaws, especially its small size. Note also that participants in this study did not have active infection with antibiotic-resistant bacteria; they were carriers for it. Do notattempt to use probiotics as sole treatment for active infection with resistant bacteria.
On a related note, preventive use of probiotics does not appear to help prevent the development of resistant bacterial strains that may arise during antibiotic treatment. 96,111 29 Probiotic treatment has also been proposed as a treatment for canker sores and as a preventative measure against colon cancer , but there is no solid evidence that it is effective.
Probiotics have shown some promise for helping to prevent cavities by antagonizing cavity-causing bacteria. 90 30 One study found that giving probiotics to certain critically ill people could help prevent multiple organ failure. 133 31 One small, placebo-controlled study found that use of L. helveticusmight improve sleep quality in seniors, for reasons that are not at all clear. 152 32 An open study found hints that probiotics might be helpful for mouth sores caused by Behcet’s syndrome. 147 33 As noted above, probiotics have shown some promise in the treatment of infections with the yeast Candida albicans. Probiotics are also proposed for the treatment of a theoretically related, but markedly controversial condition, known as yeast hypersensitivity syndrome(also known as chronic candidiasis, chronic candida, systemic candidiasis, or just candida ). As described by some alternative medicine practitioners, yeast hypersensitivity syndrome is a common problem that consists of a population explosion of the normally benign candida yeast that live in the vagina and elsewhere in the body, coupled with a type of allergic sensitivity to it. Probiotic supplements are widely recommended for this proposed condition because they establish large, healthy populations of friendly bacteria that compete with the candida that is trying to take up residence. However, there is no evidence that yeast hypersensitivity is a common problem, and virtually none that it exists at all.
In one small, 12-week study, Lactobacillus GGfailed to prove more effective than placebo for the treatment of rheumatoid arthritis . 91 34 Another study failed to find Lactobacillus GGhelpful for dyspepsia (generic stomach pain of unknown origin) in children. 130 35 A year-long open trial of 150 women failed to find Lactobacillusprobiotics effective for preventing urinary tract infections as compared to cranberry juice or no treatment. 50 36 Other studies, however, including a large (453-participant), 3-month, double-blind, placebo-controlled study of a special healthy E. coliprobiotic, did find benefits. 107,175 37 A substantial study failed to find a mixture of L. casei, L. bulgaricus, and S. thermophilusin yogurt and milk helpful for asthma in children. 142 38 But, another study found that the combination of a probiotic ( Bifidobacterium breve) and a prebiotic (galacto/fructo-oligosaccharide) may help reduce wheezing in infants with eczema. 206 39
Although we believe that they are helpful and perhaps even necessary for human health, we don't have a daily requirement for probiotic bacteria. They are living creatures, not chemicals, so they can sustain themselves in your body unless something comes along to damage them, such as antibiotics.
Cultured dairy products such as yogurt and kefir are good sources of acidophilus and other probiotic bacteria. Supplements are widely available in powder, liquid, capsule, or tablet form. Grocery stores and natural food stores both carry milk that contains live acidophilus. In addition to probiotics, related substances known as prebiotics may enhance the colonization of healthy bacteria in the intestinal tract. 140 1
Dosages of acidophilus are expressed not in grams or milligrams, but in billions of organisms. A typical daily dose should supply about 3 to 5 billion live organisms. Other probiotic bacteria are used similarly. The typical dose of S. boulardiiyeast is 500 mg twice daily (standardized to provide 3 x 10 10 -colony-forming units per gram), to be taken while traveling or at the start of using antibiotics, and continued for a few days after antibiotics are stopped.
Because probiotics are not drugs, but rather living organisms that you are trying to transplant to your digestive tract, it is necessary to take the treatment regularly. Each time you do, you reinforce the beneficial bacterial colonies in your body, which may gradually push out harmful bacteria and yeasts growing there.
The downside of using a living organism is that probiotics may die on the shelf. In fact, a study reported in 1990 found that most acidophilus capsules on the market contained no living acidophilus. 1 The situation has improved in subsequent evaluations, but still some products are substandard. 99 2 The container label should guarantee living organisms at the time of purchase, not just at the time of manufacture. Another approach is to eat acidophilus-rich foods such as yogurt, in which the bacteria are most likely still alive.
To treat or prevent vaginal infections, mix 2 tablespoons of yogurt or the contents of a couple of capsules of acidophilus with warm water and use as a douche.
Finally, in addition to increasing your intake of probiotics, you can take fructo-oligosaccharides, supplements that can promote thriving colonies of helpful bacteria in the digestive tract. (Fructo-oligosaccharides are carbohydrates found in fruit. Fructomeans "fruit," and an oligosaccharideis a type of carbohydrate.) Taking this supplement is like putting manure in a garden; it is thought to foster a healthy environment for the bacteria you want to have inside you. The typical daily dose of fructo-oligosaccharides is between 2 g and 8 g.
References
Although we believe that they are helpful and perhaps even necessary for human health, we don't have a daily requirement for probiotic bacteria. They are living creatures, not chemicals, so they can sustain themselves in your body unless something comes along to damage them, such as antibiotics.
Cultured dairy products such as yogurt and kefir are good sources of acidophilus and other probiotic bacteria. Supplements are widely available in powder, liquid, capsule, or tablet form. Grocery stores and natural food stores both carry milk that contains live acidophilus. In addition to probiotics, related substances known as prebiotics may enhance the colonization of healthy bacteria in the intestinal tract. 1
According to several studies, it appears that regular use of acidophilus and other probiotics can help prevent "traveler's diarrhea" (an illness caused by eating contaminated food, usually in developing countries). 1 One double-blind, placebo-controlled study followed 820 people traveling to southern Turkey, and found that use of Lactobacillus GGsignificantly protected against intestinal infection. 2 Other studies using S. boulardiihave found similar benefits, 3 including a double-blind, placebo-controlled trial enrolling 3,000 Austrian travelers. 4 The greatest benefits were seen in travelers who visited North Africa and Turkey. The researchers noted that the benefit depended on consistent use of the product, and that a dosage of 1,000 mg daily was more effective than 250 mg daily.
Probiotics may also help prevent or treat acute infectious diarrhea in children and adults.
A review of the literature published in 2001 found 13 double-blind, placebo-controlled trials on the use of probiotics for acute infectious diarrhea in infants and children; 10 of these trials involved treatment and 3 involved prevention. 5 Overall, the evidence suggests that probiotics can significantly reduce the duration of diarrhea and perhaps help prevent it. The evidence is strongest for the probiotic Lactobacillus GGand for infection with a particular virus called rotavirus, which causes severe diarrhea in children.
For example, one double-blind, placebo-controlled trial of 269 children (ages 1 month to 3 years) with acute diarrhea found that those treated with Lactobacillus GGrecovered more quickly than those given placebo. 6 The best results were seen among children with rotavirus infection. Similar results with Lactobacillus GGwere seen in a double-blind study of 71 children. 7 However, 224 young Chinese children with severe, acute diarrhea found no benefit from lactose-free formula supplemented with Bifidobacteriaand S. thermophilus, suggesting that probiotics may not be as useful for cases of severe, dehydrating diarrhea. 8 Also, Lactobacillus rhamnosusGG is not always associated with improvement. When given for 10 days to 229 infants from rural India hospitalized with acute diarrhea it did not reduce the severity of the diarrhea during that time period. 9 In addition, a double-blind study evaluated the possible benefits of the probiotic L. reuteriin 66 children with rotavirus diarrhea. 10 The study found that treatment shortened the duration of symptoms, and the higher the dose, the better the effect. Similar benefits were seen in a placebo-controlled trial of 151 infants and children given the probiotic Escherichia coliNissle 1917 (a safe strain of E. coli) for 21 days for nonspecific (presumably viral) cases of mild to moderate diarrhea. 11 A double-blind, placebo-controlled study of 81 hospitalized children found that treatment with Lactobacillus GGreduced the risk of developing diarrhea, particularly rotavirus infection. 12 A double-blind, placebo-controlled study found that Lactobacillus GGhelped prevent diarrhea in 204 undernourished children. 13 Other studies, though not entirely consistent, generally indicate that the probiotics B. bifidum, Streptococcus thermophilus, L. casei, Lactobacillus LB, and S. boulardii—both individually and combined with L. reuteriand L. rhamnosus—may also help prevent or treat diarrhea in infants and children. 14 One study found that bacteria in the B. bifidumfamily can kill numerous bacteria that cause diarrhea. 15 Keep in mind that diarrhea in young children can be serious. If it persists for more than a day, consult a physician.
A large (211-participant), double-blind, placebo-controlled study found that adults with diarrhea can benefit from probiotic treatment as well. 16 Another study found that regular use of probiotics could help prevent gastrointestinal infections in adults. 17
The results of many, but not all, double-blind and open trials suggest that probiotics, especially S. boulardiiand Lactobacillus GG, may help prevent or treat antibiotic-related diarrhea. 18 For example, one study evaluated 180 people, who received either placebo or 1,000 mg of saccharomyces daily along with their antibiotic treatment, and found that the treated group developed diarrhea significantly less often. 19 A similar study of 193 people also found benefit. 20 And, at least 3 additional studies involving adults found that various species of Lactobacillus, taken either alone in combination, to be beneficial, 21 even in cases of Clostridium difficile, the most serious cause of antibiotic-induced diarrhea. 22 However, a study of 302 people found no benefit with Lactobacillus GG. 23 And, a review of four probiotic studies found insufficient evidence for their effectiveness in the treatment of Clostridium difficile, the most serious cause of antibiotic-induced diarrhea. 24 Although taking probiotic organisms in the proper concentration may be beneficial for antibiotic-induced diarrhea, at least one study found that consuming fresh yogurt during antibiotic treatments had no significant effect on the incidence of diarrhea. 25
Note:Diarrhea that occurs in the context of antibiotics may be dangerous; for this reason, physician consultation is essential.
Two double-blind, placebo-controlled studies enrolling a total of almost 700 people undergoing radiation therapy for cancer found that use of probiotics significantly improved radiation-induced diarrhea. 26 Similar evidence supports the use of Lactobacillus rhamnosus, 27 as well as a special, nonpathogenic form of E. coli. 28 However, of 85 women receiving pelvic radiation for cervical or uterine cancer, those who consumed a liquid yogurt preparation enriched with Lactobacillus caseihad no less diarrhea than those who took a placebo drink. 29 Small double-blind studies suggest S. boulardiimight be helpful for treating chronic diarrhea in people with HIV, hospitalized patients being tube-fed, and people with Crohn's disease. 30 Premature infants weighing less than 2,500 grams (5.5 pounds) are at risk for a life-threatening intestinal condition called necrotizing enterocolitis (NEC). In a study that pooled the results of 9 randomized, placebo-controlled trials involving 1,425 infants, probiotic supplementation significantly reduced the occurrence of NEC and death associated with it. 31 And, a subsequent study found similar benefits in very low birth weight infants weighing less than 1,500 grams (3.3 pounds). 32
The conditions Crohn’s disease and ulcerative colitis fall into the family of conditions known as inflammatory bowel disease. Chronic diarrhea is a common feature of these conditions.
A double-blind trial of 116 people with ulcerative colitis compared probiotic treatment against a relatively low dose of the standard drug mesalazine. 33 The results suggest that probiotic treatment might be equally effective as low-dose mesalazine for controlling symptoms and maintaining remission. Evidence of benefit was seen in other trials as well. 34 One preliminary study found S. boulardiihelpful for mild diarrhea in stable Crohn’s disease. 35 However, two studies failed to find benefit with Lactobacillusprobiotics, 36 and in an analysis of 8 randomized, placebo-controlled studies, probiotics were ineffective at maintaining remission in Crohn’s disease patients. 37 Probiotics might be useful for people with ulcerative colitis who have had part or all of the colon removed. Such people frequently develop a complication called pouchitis, inflammation of part of the remaining intestine. A 9-month, double-blind trial of 40 people found that a combination of three probiotic bacteria could significantly reduce the risk of a pouchitis flare-up in people with chronic pouchitis. 38 Participants were given either placebo or a mixture of various probiotics, including four strains of Lactobacilli, three strains of Bifidobacteria, and one strain of Streptococcus salivarius. The results showed that treated people were far less likely to have relapses of pouchitis. Another study found that probiotics used right after surgery can help prevent pouchitis from developing at all. 39 One study, however, failed to find benefit with Lactobacillus johnsoniiin people with Crohn’s disease who have undergone a similar operation. 40 Finally, some evidence hints that probiotics might reduce the joint pain that commonly occurs in people with either kind of inflammatory bowel disease. 41
People with irritable bowel syndrome (IBS) experience crampy digestive pain as well as alternating diarrhea and constipation and other symptoms. Although the cause of irritable bowel syndrome is not known, one possibility is a disturbance in healthy intestinal bacteria. Based on this theory, probiotics have been tried as a treatment for IBS, with some success.
For example, in a 6-week double-blind, placebo-controlled trial of 274 people with constipation-predominant irritable bowel syndrome, use of a probiotic formula containing Bifidobacterium animalissignificantly reduced discomfort and increased stool frequency. 42 And, 266 women with constipation who consumed yogurt containing Bifidobacterium animalisand the prebiotic fructo-oligosaccharides twice daily for two weeks experienced significant improvement compared to women consuming regular yogurt as a placebo. 43 Finally, in another trial of 298 IBS patients, 8 weeks of treatment with beneficial Escherichia colireduced typical symptoms compared to placebo. 44 Benefits were seen in 8 other small, double-blind trials as well, using L. plantarum, 45 L. acidophilus, 46 L. rhamnosus, 47 L. salivarusand Bifidobacterium, 48 as well as proprietary probiotic combinations including various strains. 49 Benefits have also been seen with combination prebiotic /probiotic formulas 50 and prebiotics alone. 51 Of course, other studies have failed to find probiotics more effective than placebo. 52 Two studies that pooled previous randomized trials on the use of probiotics for IBS came to similar conclusions: probiotics appear to offer some benefit, most notably for global symptoms and abdominal discomfort. However, these two studies were unable to determine which probiotic species were most effective. 53
Use of probiotics during pregnancy and after childbirth may reduce risk of childhood eczema . In a very large, long-term, double-blind study, 1,223 pregnant women were given either placebo or a probiotic mixture (containing Lactobacilliand Bifidobacteria) beginning 2-4 weeks before delivery. 54 Their newborn children then received either probiotics or placebo for six months. The results showed that the probiotics mixture markedly reduced the incidence of eczema (though not of other allergic diseases). However, in a follow-up to this study, researchers found that the probiotic supplementation was not associated with reduced eczema in children followed through age 5. The probiotics also had no effect on allergic rhinitis or asthma. 55 Another study also yielded marginal results, 56 and a third study involving only lactobacillus found no benefit at all for the prevention of eczema. This latter study actually demonstrated a modestly increased the risk of wheezing bronchitis in infants who took the probiotic. 57 But, some probiotics combined with prebiotics may help to reduce wheezing in infants with eczema. For example, Bifidobacterium breveand a galacto-/fructo-oligosaccharide mixture (Immunofortis) showed benefit in one randomized study involving 90 infants. 58
Bifidobacterium longumand Lactobacillus rhamnosussupplementation did not reduce incidence of eczema atopic dermatitis or allergic sensitization at 12 months among Asian infants at risk of allergic diseases. 59 Researchers in another study concluded that not all probiotics are created equal. In this placebo-controlled study involving pregnant women and their infants, Lactobacillus rhamnosusreduced the incidence of eczema in the children, but a strain of Bifidobacterium animalisdid not. 60 According to some but not all studies, infants who already have eczema may benefit from probiotics. 61 However, a careful review of 12 studies involving a total of 781 children found no convincing evidence that probiotics can effectively treat eczema in this age group. 62 If probiotics are beneficial for childhood eczema, they are probably more effective at preventing the condition rather than treating it. A carefully conducted review of numerous studies cautiously concluded that probiotics may help reduce the risk of eczema in infants and children, particularly those at high risk. 63 And two subsequent reviews found that probiotics were more effective at preventing childhood eczema, particularly when given both to mother (before birth) and infant. 64
A number of studies suggest that various probiotics can enhance immune function . One 12-week, double-blind, placebo-controlled trial evaluated 25 healthy elderly people, half of whom were given milk containing a particular strain of Bifidobacterium lactis, the others milk alone. 65 The results showed various changes in immune parameters which the researchers took as possibly indicating improved immune function. Another double-blind, placebo-controlled study of 50 people using B. lactishad similar results. 66 A 7-month, double-blind, placebo-controlled study of 571 children in daycare centers in Finland found that use of milk fortified with Lactobacillus GGreduced the number and severity of respiratory infections. 67 In another controlled trial, probiotics ( Lactobacillus rhamnosus GGand Bifidobacterium lactisBb-12) given daily to infants in their formula significantly reduced the risk of acute otitis media and recurrent respiratory infections during the first year of life compared to placebo. 68 Benefits were seen in three other large studies, in which probiotics combined with multivitamins and minerals helped prevent colds (or reduce their duration and severity) in adults. 69 70 However, a smaller and shorter study failed to find any effect on respiratory infections. 71 Similarly, Lactobacillus fermentumgiven to 20 healthy elite distance runners over a 4-month period during winter training was significantly more effective at reducing the number and severity of respiratory symptoms compared with a placebo. 72 One study found that Lactobacillus GGor L. acidophilusmay improve the immune response to vaccinations. 73
An 8-week, double-blind, placebo-controlled trial of 70 overweight people found that a probiotic treatment containing S. thermophilusand Enterococcus faeciumcould reduce LDL ("bad") cholesterol by about 8%. 74 Similarly positive results were seen in other short-term trials of various probiotics. 75 However, a 6-month, double-blind, placebo-controlled trial found no long-term benefit. 76 Researchers speculate that participants stopped using the product regularly toward the later parts of the study.
The addition of the probiotic Lactobacillus rhamnosusto regular was no better than than placebo in 77 patients with chronic rhinosinusitis. 77
Evidence from many but not all double-blind, placebo-controlled trials suggests that probiotics may be helpful for many types of diarrhea , as well as for irritable bowel syndrome . 1 Additionally, probiotics have shown some promise for preventing or treating eczema . 2 Probiotics may be helpful for controlling symptoms and maintaining remission in ulcerative colitis . 3 However, probiotics may be less useful for inducingremission; when probiotics were added to standard medications used for induction of remission, no additional benefits were seen in a study of people with mild-to-moderate ulcerative colitis. 4 Probiotics might help prevent colds , 5 possibly by improving immunity . 6 On a related note, one small, double-blind study found evidence that use of the probiotic bacteria Lactobacillus fermentumimproved the effectiveness of the influenza vaccine. 7 (The probiotic supplement was taken in two doses. One was taken two weeks before the vaccine, and the other was taken two weeks after.)
Although probiotics are widely used to prevent or treat vaginal yeast ( Candida albicans) infections, evidence regarding potential benefit remains incomplete and inconsistent. 8 A small trial of 55 women with vulvovaginal candidiasis did demonstrate that daily Lactobacillus rhamnosusand L. reuterisupplementation for 4 weeks combined with single dose fluconazole (an anti-fungal medication) decreased symptoms compared to fluconazole alone. 9 Another large, well-designed trial, however, failed to find a Lactobacilluspreparation helpful for preventing yeast infections caused by antibiotics. 10 One study did find that probiotics might reduce levels of Candida albicansin the mouth. 11 The bacteria Gardnerella vaginaliscan cause a different type of vaginal infection; as with vaginal yeast infections, probiotics have shown some promise for this condition, but evidence remains inconclusive. 12 A trial of 64 women taking a single dose of tinidazole for bacterial vaginosis suggests that women who also took daily probiotics capsules had better cure rates at 4 weeks. 13 The bacteria Helicobacter pyloriis the main cause of ulcers in the stomach and duodenum. Antibiotics can kill H. pylori, but more than one must be used at the same time, and, even then, the bacteria is not necessarily eradicated. Probiotics may be helpful. Evidence suggests that various probiotics can inhibit the growth of H. pylori. 14 While this effect does not appear to be strong enough for probiotic treatment to eradicate H. pylorion its own, preliminary evidence, including several small double-blind trials, suggest that various probiotics may help standard antibiotic therapy work better, reducing side effects and possibly increasing rate of eradication. 15 Some, but not, all preliminary double-blind trials suggest that probiotics might improve cholesterol profile. 16 In addition, milk fermented by probiotics may slightly improve blood pressure levels. 17 18 Various probiotics might be helpful for allergic rhinitis (hay fever). 19 While there is some evidence that probiotics can help reduce symptoms of milk allergies, 20 one study found that adding probiotics to infant cow’s milk formula was not helpful. 21 One interesting study found that the use of probiotics during pregnancy and breastfeeding may decrease the likelihood that a highly allergic mother will pass her allergic tendencies to her breastfed infant. 22 One double-blind, placebo-controlled study of 70 people with chronic constipation found some evidence of benefit with Lactobacillus casei Shirota. 23 Another study found that Lactobacillus rhamnosuswas helpful for chronic constipation in children. 24 A small trial also found benefits in children, this time with a mixture of bifidobacteriaand lactobacilli. 25 In another study, a combination of B. lactisand B. longusshowed promise for improving bowel regularity in nursing home residents. 26 Finally, in a 6-week double-blind, placebo-controlled trial of 274 people with constipation-predominant irritable bowel syndrome, use of a probiotic formula containing B. animalissignificantly improved stool frequency. 27 A preliminary double-blind, placebo-controlled study found evidence that Lactobacillus GGmight potentially be helpful for treating antibiotic-resistant bacteria. 28 This small study followed 23 people with severe kidney disease who tested positive for vancomycin-resistant bacteria in the stool. (Vancomycin is one of the main “last-ditch” antibiotics for treatment of resistant bacteria.) Use of a yogurt product containing L. rhamnosusappeared to be more effective at ridding the gastrointestinal tract of these bacteria than placebo. However, the study suffered from a number of flaws, especially its small size. Note also that participants in this study did not have active infection with antibiotic-resistant bacteria; they were carriers for it. Do notattempt to use probiotics as sole treatment for active infection with resistant bacteria.
On a related note, preventive use of probiotics does not appear to help prevent the development of resistant bacterial strains that may arise during antibiotic treatment. 29 Probiotic treatment has also been proposed as a treatment for canker sores and as a preventative measure against colon cancer , but there is no solid evidence that it is effective.
Probiotics have shown some promise for helping to prevent cavities by antagonizing cavity-causing bacteria. 30 One study found that giving probiotics to certain critically ill people could help prevent multiple organ failure. 31 One small, placebo-controlled study found that use of L. helveticusmight improve sleep quality in seniors, for reasons that are not at all clear. 32 An open study found hints that probiotics might be helpful for mouth sores caused by Behcet’s syndrome. 33 As noted above, probiotics have shown some promise in the treatment of infections with the yeast Candida albicans. Probiotics are also proposed for the treatment of a theoretically related, but markedly controversial condition, known as yeast hypersensitivity syndrome(also known as chronic candidiasis, chronic candida, systemic candidiasis, or just candida ). As described by some alternative medicine practitioners, yeast hypersensitivity syndrome is a common problem that consists of a population explosion of the normally benign candida yeast that live in the vagina and elsewhere in the body, coupled with a type of allergic sensitivity to it. Probiotic supplements are widely recommended for this proposed condition because they establish large, healthy populations of friendly bacteria that compete with the candida that is trying to take up residence. However, there is no evidence that yeast hypersensitivity is a common problem, and virtually none that it exists at all.
In one small, 12-week study, Lactobacillus GGfailed to prove more effective than placebo for the treatment of rheumatoid arthritis . 34 Another study failed to find Lactobacillus GGhelpful for dyspepsia (generic stomach pain of unknown origin) in children. 35 A year-long open trial of 150 women failed to find Lactobacillusprobiotics effective for preventing urinary tract infections as compared to cranberry juice or no treatment. 36 Other studies, however, including a large (453-participant), 3-month, double-blind, placebo-controlled study of a special healthy E. coliprobiotic, did find benefits. 37 A substantial study failed to find a mixture of L. casei, L. bulgaricus, and S. thermophilusin yogurt and milk helpful for asthma in children. 38 But, another study found that the combination of a probiotic ( Bifidobacterium breve) and a prebiotic (galacto/fructo-oligosaccharide) may help reduce wheezing in infants with eczema. 39
Although we believe that they are helpful and perhaps even necessary for human health, we don't have a daily requirement for probiotic bacteria. They are living creatures, not chemicals, so they can sustain themselves in your body unless something comes along to damage them, such as antibiotics.
Cultured dairy products such as yogurt and kefir are good sources of acidophilus and other probiotic bacteria. Supplements are widely available in powder, liquid, capsule, or tablet form. Grocery stores and natural food stores both carry milk that contains live acidophilus. In addition to probiotics, related substances known as prebiotics may enhance the colonization of healthy bacteria in the intestinal tract. 1
Dosages of acidophilus are expressed not in grams or milligrams, but in billions of organisms. A typical daily dose should supply about 3 to 5 billion live organisms. Other probiotic bacteria are used similarly. The typical dose of S. boulardiiyeast is 500 mg twice daily (standardized to provide 3 x 10 10 -colony-forming units per gram), to be taken while traveling or at the start of using antibiotics, and continued for a few days after antibiotics are stopped.
Because probiotics are not drugs, but rather living organisms that you are trying to transplant to your digestive tract, it is necessary to take the treatment regularly. Each time you do, you reinforce the beneficial bacterial colonies in your body, which may gradually push out harmful bacteria and yeasts growing there.
The downside of using a living organism is that probiotics may die on the shelf. In fact, a study reported in 1990 found that most acidophilus capsules on the market contained no living acidophilus. 1 The situation has improved in subsequent evaluations, but still some products are substandard. 2 The container label should guarantee living organisms at the time of purchase, not just at the time of manufacture. Another approach is to eat acidophilus-rich foods such as yogurt, in which the bacteria are most likely still alive.
To treat or prevent vaginal infections, mix 2 tablespoons of yogurt or the contents of a couple of capsules of acidophilus with warm water and use as a douche.
Finally, in addition to increasing your intake of probiotics, you can take fructo-oligosaccharides, supplements that can promote thriving colonies of helpful bacteria in the digestive tract. (Fructo-oligosaccharides are carbohydrates found in fruit. Fructomeans "fruit," and an oligosaccharideis a type of carbohydrate.) Taking this supplement is like putting manure in a garden; it is thought to foster a healthy environment for the bacteria you want to have inside you. The typical daily dose of fructo-oligosaccharides is between 2 g and 8 g.
Lactobacillus acidophilusis a "friendly" strain of bacteria used to make yogurt and cheese. Although we are born without it, acidophilus soon establishes itself in our intestines and helps prevent intestinal infections. Acidophilus also flourishes in the vagina, where it protects women against yeast infections.
Acidophilus is one of several microbes known collectively as probiotics(literally, "pro life," indicating that they are bacteria and yeasts that help rather than harm). Others include the bacteria L. bulgaricus, L. reuteri, L. plantarum, L. casei, B. bifidus, S. salivarius, and S. thermophilusand the yeast Saccharomyces boulardii. Your digestive tract is like a rain forest ecosystem with billions of bacteria and yeasts rather than trees, frogs, and leopards. Some of these internal inhabitants are more helpful to your body than others. Acidophilus and related probiotics not only help the digestive tract function, they also reduce the presence of less healthful organisms by competing with them for the limited space available. For this reason, use of probiotics can help prevent infectious diarrhea.
Antibiotics can disturb the balance of your "inner rain forest" by killing friendly bacteria. When this happens, harmful bacteria and yeasts can move in and flourish. This can lead to vaginal yeast infections. Conversely, it appears that the regular use of probiotics can help prevent vaginal infections and generally improve the health of the gastrointestinal system. Whenever you take antibiotics, you should probably take probiotics as well and continue them for some time after you are done with the course of treatment.
According to several studies, it appears that regular use of acidophilus and other probiotics can help prevent "traveler's diarrhea" (an illness caused by eating contaminated food, usually in developing countries). 1 One double-blind, placebo-controlled study followed 820 people traveling to southern Turkey, and found that use of Lactobacillus GGsignificantly protected against intestinal infection. 2 Other studies using S. boulardiihave found similar benefits, 3 including a double-blind, placebo-controlled trial enrolling 3,000 Austrian travelers. 4 The greatest benefits were seen in travelers who visited North Africa and Turkey. The researchers noted that the benefit depended on consistent use of the product, and that a dosage of 1,000 mg daily was more effective than 250 mg daily.
Probiotics may also help prevent or treat acute infectious diarrhea in children and adults.
A review of the literature published in 2001 found 13 double-blind, placebo-controlled trials on the use of probiotics for acute infectious diarrhea in infants and children; 10 of these trials involved treatment and 3 involved prevention. 5 Overall, the evidence suggests that probiotics can significantly reduce the duration of diarrhea and perhaps help prevent it. The evidence is strongest for the probiotic Lactobacillus GGand for infection with a particular virus called rotavirus, which causes severe diarrhea in children.
For example, one double-blind, placebo-controlled trial of 269 children (ages 1 month to 3 years) with acute diarrhea found that those treated with Lactobacillus GGrecovered more quickly than those given placebo. 6 The best results were seen among children with rotavirus infection. Similar results with Lactobacillus GGwere seen in a double-blind study of 71 children. 7 However, 224 young Chinese children with severe, acute diarrhea found no benefit from lactose-free formula supplemented with Bifidobacteriaand S. thermophilus, suggesting that probiotics may not be as useful for cases of severe, dehydrating diarrhea. 8 Also, Lactobacillus rhamnosusGG is not always associated with improvement. When given for 10 days to 229 infants from rural India hospitalized with acute diarrhea it did not reduce the severity of the diarrhea during that time period. 9 In addition, a double-blind study evaluated the possible benefits of the probiotic L. reuteriin 66 children with rotavirus diarrhea. 10 The study found that treatment shortened the duration of symptoms, and the higher the dose, the better the effect. Similar benefits were seen in a placebo-controlled trial of 151 infants and children given the probiotic Escherichia coliNissle 1917 (a safe strain of E. coli) for 21 days for nonspecific (presumably viral) cases of mild to moderate diarrhea. 11 A double-blind, placebo-controlled study of 81 hospitalized children found that treatment with Lactobacillus GGreduced the risk of developing diarrhea, particularly rotavirus infection. 12 A double-blind, placebo-controlled study found that Lactobacillus GGhelped prevent diarrhea in 204 undernourished children. 13 Other studies, though not entirely consistent, generally indicate that the probiotics B. bifidum, Streptococcus thermophilus, L. casei, Lactobacillus LB, and S. boulardii—both individually and combined with L. reuteriand L. rhamnosus—may also help prevent or treat diarrhea in infants and children. 14 One study found that bacteria in the B. bifidumfamily can kill numerous bacteria that cause diarrhea. 15 Keep in mind that diarrhea in young children can be serious. If it persists for more than a day, consult a physician.
A large (211-participant), double-blind, placebo-controlled study found that adults with diarrhea can benefit from probiotic treatment as well. 16 Another study found that regular use of probiotics could help prevent gastrointestinal infections in adults. 17
The results of many, but not all, double-blind and open trials suggest that probiotics, especially S. boulardiiand Lactobacillus GG, may help prevent or treat antibiotic-related diarrhea. 18 For example, one study evaluated 180 people, who received either placebo or 1,000 mg of saccharomyces daily along with their antibiotic treatment, and found that the treated group developed diarrhea significantly less often. 19 A similar study of 193 people also found benefit. 20 And, at least 3 additional studies involving adults found that various species of Lactobacillus, taken either alone in combination, to be beneficial, 21 even in cases of Clostridium difficile, the most serious cause of antibiotic-induced diarrhea. 22 However, a study of 302 people found no benefit with Lactobacillus GG. 23 And, a review of four probiotic studies found insufficient evidence for their effectiveness in the treatment of Clostridium difficile, the most serious cause of antibiotic-induced diarrhea. 24 Although taking probiotic organisms in the proper concentration may be beneficial for antibiotic-induced diarrhea, at least one study found that consuming fresh yogurt during antibiotic treatments had no significant effect on the incidence of diarrhea. 25
Note:Diarrhea that occurs in the context of antibiotics may be dangerous; for this reason, physician consultation is essential.
Two double-blind, placebo-controlled studies enrolling a total of almost 700 people undergoing radiation therapy for cancer found that use of probiotics significantly improved radiation-induced diarrhea. 26 Similar evidence supports the use of Lactobacillus rhamnosus, 27 as well as a special, nonpathogenic form of E. coli. 28 However, of 85 women receiving pelvic radiation for cervical or uterine cancer, those who consumed a liquid yogurt preparation enriched with Lactobacillus caseihad no less diarrhea than those who took a placebo drink. 29 Small double-blind studies suggest S. boulardiimight be helpful for treating chronic diarrhea in people with HIV, hospitalized patients being tube-fed, and people with Crohn's disease. 30 Premature infants weighing less than 2,500 grams (5.5 pounds) are at risk for a life-threatening intestinal condition called necrotizing enterocolitis (NEC). In a study that pooled the results of 9 randomized, placebo-controlled trials involving 1,425 infants, probiotic supplementation significantly reduced the occurrence of NEC and death associated with it. 31 And, a subsequent study found similar benefits in very low birth weight infants weighing less than 1,500 grams (3.3 pounds). 32
The conditions Crohn’s disease and ulcerative colitis fall into the family of conditions known as inflammatory bowel disease. Chronic diarrhea is a common feature of these conditions.
A double-blind trial of 116 people with ulcerative colitis compared probiotic treatment against a relatively low dose of the standard drug mesalazine. 33 The results suggest that probiotic treatment might be equally effective as low-dose mesalazine for controlling symptoms and maintaining remission. Evidence of benefit was seen in other trials as well. 34 One preliminary study found S. boulardiihelpful for mild diarrhea in stable Crohn’s disease. 35 However, two studies failed to find benefit with Lactobacillusprobiotics, 36 and in an analysis of 8 randomized, placebo-controlled studies, probiotics were ineffective at maintaining remission in Crohn’s disease patients. 37 Probiotics might be useful for people with ulcerative colitis who have had part or all of the colon removed. Such people frequently develop a complication called pouchitis, inflammation of part of the remaining intestine. A 9-month, double-blind trial of 40 people found that a combination of three probiotic bacteria could significantly reduce the risk of a pouchitis flare-up in people with chronic pouchitis. 38 Participants were given either placebo or a mixture of various probiotics, including four strains of Lactobacilli, three strains of Bifidobacteria, and one strain of Streptococcus salivarius. The results showed that treated people were far less likely to have relapses of pouchitis. Another study found that probiotics used right after surgery can help prevent pouchitis from developing at all. 39 One study, however, failed to find benefit with Lactobacillus johnsoniiin people with Crohn’s disease who have undergone a similar operation. 40 Finally, some evidence hints that probiotics might reduce the joint pain that commonly occurs in people with either kind of inflammatory bowel disease. 41
People with irritable bowel syndrome (IBS) experience crampy digestive pain as well as alternating diarrhea and constipation and other symptoms. Although the cause of irritable bowel syndrome is not known, one possibility is a disturbance in healthy intestinal bacteria. Based on this theory, probiotics have been tried as a treatment for IBS, with some success.
For example, in a 6-week double-blind, placebo-controlled trial of 274 people with constipation-predominant irritable bowel syndrome, use of a probiotic formula containing Bifidobacterium animalissignificantly reduced discomfort and increased stool frequency. 42 And, 266 women with constipation who consumed yogurt containing Bifidobacterium animalisand the prebiotic fructo-oligosaccharides twice daily for two weeks experienced significant improvement compared to women consuming regular yogurt as a placebo. 43 Finally, in another trial of 298 IBS patients, 8 weeks of treatment with beneficial Escherichia colireduced typical symptoms compared to placebo. 44 Benefits were seen in 8 other small, double-blind trials as well, using L. plantarum, 45 L. acidophilus, 46 L. rhamnosus, 47 L. salivarusand Bifidobacterium, 48 as well as proprietary probiotic combinations including various strains. 49 Benefits have also been seen with combination prebiotic /probiotic formulas 50 and prebiotics alone. 51 Of course, other studies have failed to find probiotics more effective than placebo. 52 Two studies that pooled previous randomized trials on the use of probiotics for IBS came to similar conclusions: probiotics appear to offer some benefit, most notably for global symptoms and abdominal discomfort. However, these two studies were unable to determine which probiotic species were most effective. 53
Use of probiotics during pregnancy and after childbirth may reduce risk of childhood eczema . In a very large, long-term, double-blind study, 1,223 pregnant women were given either placebo or a probiotic mixture (containing Lactobacilliand Bifidobacteria) beginning 2-4 weeks before delivery. 54 Their newborn children then received either probiotics or placebo for six months. The results showed that the probiotics mixture markedly reduced the incidence of eczema (though not of other allergic diseases). However, in a follow-up to this study, researchers found that the probiotic supplementation was not associated with reduced eczema in children followed through age 5. The probiotics also had no effect on allergic rhinitis or asthma. 55 Another study also yielded marginal results, 56 and a third study involving only lactobacillus found no benefit at all for the prevention of eczema. This latter study actually demonstrated a modestly increased the risk of wheezing bronchitis in infants who took the probiotic. 57 But, some probiotics combined with prebiotics may help to reduce wheezing in infants with eczema. For example, Bifidobacterium breveand a galacto-/fructo-oligosaccharide mixture (Immunofortis) showed benefit in one randomized study involving 90 infants. 58
Bifidobacterium longumand Lactobacillus rhamnosussupplementation did not reduce incidence of eczema atopic dermatitis or allergic sensitization at 12 months among Asian infants at risk of allergic diseases. 59 Researchers in another study concluded that not all probiotics are created equal. In this placebo-controlled study involving pregnant women and their infants, Lactobacillus rhamnosusreduced the incidence of eczema in the children, but a strain of Bifidobacterium animalisdid not. 60 According to some but not all studies, infants who already have eczema may benefit from probiotics. 61 However, a careful review of 12 studies involving a total of 781 children found no convincing evidence that probiotics can effectively treat eczema in this age group. 62 If probiotics are beneficial for childhood eczema, they are probably more effective at preventing the condition rather than treating it. A carefully conducted review of numerous studies cautiously concluded that probiotics may help reduce the risk of eczema in infants and children, particularly those at high risk. 63 And two subsequent reviews found that probiotics were more effective at preventing childhood eczema, particularly when given both to mother (before birth) and infant. 64
A number of studies suggest that various probiotics can enhance immune function . One 12-week, double-blind, placebo-controlled trial evaluated 25 healthy elderly people, half of whom were given milk containing a particular strain of Bifidobacterium lactis, the others milk alone. 65 The results showed various changes in immune parameters which the researchers took as possibly indicating improved immune function. Another double-blind, placebo-controlled study of 50 people using B. lactishad similar results. 66 A 7-month, double-blind, placebo-controlled study of 571 children in daycare centers in Finland found that use of milk fortified with Lactobacillus GGreduced the number and severity of respiratory infections. 67 In another controlled trial, probiotics ( Lactobacillus rhamnosus GGand Bifidobacterium lactisBb-12) given daily to infants in their formula significantly reduced the risk of acute otitis media and recurrent respiratory infections during the first year of life compared to placebo. 68 Benefits were seen in three other large studies, in which probiotics combined with multivitamins and minerals helped prevent colds (or reduce their duration and severity) in adults. 69 70 However, a smaller and shorter study failed to find any effect on respiratory infections. 71 Similarly, Lactobacillus fermentumgiven to 20 healthy elite distance runners over a 4-month period during winter training was significantly more effective at reducing the number and severity of respiratory symptoms compared with a placebo. 72 One study found that Lactobacillus GGor L. acidophilusmay improve the immune response to vaccinations. 73
An 8-week, double-blind, placebo-controlled trial of 70 overweight people found that a probiotic treatment containing S. thermophilusand Enterococcus faeciumcould reduce LDL ("bad") cholesterol by about 8%. 74 Similarly positive results were seen in other short-term trials of various probiotics. 75 However, a 6-month, double-blind, placebo-controlled trial found no long-term benefit. 76 Researchers speculate that participants stopped using the product regularly toward the later parts of the study.
The addition of the probiotic Lactobacillus rhamnosusto regular was no better than than placebo in 77 patients with chronic rhinosinusitis. 77
Evidence from many but not all double-blind, placebo-controlled trials suggests that probiotics may be helpful for many types of diarrhea , as well as for irritable bowel syndrome . 1 Additionally, probiotics have shown some promise for preventing or treating eczema . 2 Probiotics may be helpful for controlling symptoms and maintaining remission in ulcerative colitis . 3 However, probiotics may be less useful for inducingremission; when probiotics were added to standard medications used for induction of remission, no additional benefits were seen in a study of people with mild-to-moderate ulcerative colitis. 4 Probiotics might help prevent colds , 5 possibly by improving immunity . 6 On a related note, one small, double-blind study found evidence that use of the probiotic bacteria Lactobacillus fermentumimproved the effectiveness of the influenza vaccine. 7 (The probiotic supplement was taken in two doses. One was taken two weeks before the vaccine, and the other was taken two weeks after.)
Although probiotics are widely used to prevent or treat vaginal yeast ( Candida albicans) infections, evidence regarding potential benefit remains incomplete and inconsistent. 8 A small trial of 55 women with vulvovaginal candidiasis did demonstrate that daily Lactobacillus rhamnosusand L. reuterisupplementation for 4 weeks combined with single dose fluconazole (an anti-fungal medication) decreased symptoms compared to fluconazole alone. 9 Another large, well-designed trial, however, failed to find a Lactobacilluspreparation helpful for preventing yeast infections caused by antibiotics. 10 One study did find that probiotics might reduce levels of Candida albicansin the mouth. 11 The bacteria Gardnerella vaginaliscan cause a different type of vaginal infection; as with vaginal yeast infections, probiotics have shown some promise for this condition, but evidence remains inconclusive. 12 A trial of 64 women taking a single dose of tinidazole for bacterial vaginosis suggests that women who also took daily probiotics capsules had better cure rates at 4 weeks. 13 The bacteria Helicobacter pyloriis the main cause of ulcers in the stomach and duodenum. Antibiotics can kill H. pylori, but more than one must be used at the same time, and, even then, the bacteria is not necessarily eradicated. Probiotics may be helpful. Evidence suggests that various probiotics can inhibit the growth of H. pylori. 14 While this effect does not appear to be strong enough for probiotic treatment to eradicate H. pylorion its own, preliminary evidence, including several small double-blind trials, suggest that various probiotics may help standard antibiotic therapy work better, reducing side effects and possibly increasing rate of eradication. 15 Some, but not, all preliminary double-blind trials suggest that probiotics might improve cholesterol profile. 16 In addition, milk fermented by probiotics may slightly improve blood pressure levels. 17 18 Various probiotics might be helpful for allergic rhinitis (hay fever). 19 While there is some evidence that probiotics can help reduce symptoms of milk allergies, 20 one study found that adding probiotics to infant cow’s milk formula was not helpful. 21 One interesting study found that the use of probiotics during pregnancy and breastfeeding may decrease the likelihood that a highly allergic mother will pass her allergic tendencies to her breastfed infant. 22 One double-blind, placebo-controlled study of 70 people with chronic constipation found some evidence of benefit with Lactobacillus casei Shirota. 23 Another study found that Lactobacillus rhamnosuswas helpful for chronic constipation in children. 24 A small trial also found benefits in children, this time with a mixture of bifidobacteriaand lactobacilli. 25 In another study, a combination of B. lactisand B. longusshowed promise for improving bowel regularity in nursing home residents. 26 Finally, in a 6-week double-blind, placebo-controlled trial of 274 people with constipation-predominant irritable bowel syndrome, use of a probiotic formula containing B. animalissignificantly improved stool frequency. 27 A preliminary double-blind, placebo-controlled study found evidence that Lactobacillus GGmight potentially be helpful for treating antibiotic-resistant bacteria. 28 This small study followed 23 people with severe kidney disease who tested positive for vancomycin-resistant bacteria in the stool. (Vancomycin is one of the main “last-ditch” antibiotics for treatment of resistant bacteria.) Use of a yogurt product containing L. rhamnosusappeared to be more effective at ridding the gastrointestinal tract of these bacteria than placebo. However, the study suffered from a number of flaws, especially its small size. Note also that participants in this study did not have active infection with antibiotic-resistant bacteria; they were carriers for it. Do notattempt to use probiotics as sole treatment for active infection with resistant bacteria.
On a related note, preventive use of probiotics does not appear to help prevent the development of resistant bacterial strains that may arise during antibiotic treatment. 29 Probiotic treatment has also been proposed as a treatment for canker sores and as a preventative measure against colon cancer , but there is no solid evidence that it is effective.
Probiotics have shown some promise for helping to prevent cavities by antagonizing cavity-causing bacteria. 30 One study found that giving probiotics to certain critically ill people could help prevent multiple organ failure. 31 One small, placebo-controlled study found that use of L. helveticusmight improve sleep quality in seniors, for reasons that are not at all clear. 32 An open study found hints that probiotics might be helpful for mouth sores caused by Behcet’s syndrome. 33 As noted above, probiotics have shown some promise in the treatment of infections with the yeast Candida albicans. Probiotics are also proposed for the treatment of a theoretically related, but markedly controversial condition, known as yeast hypersensitivity syndrome(also known as chronic candidiasis, chronic candida, systemic candidiasis, or just candida ). As described by some alternative medicine practitioners, yeast hypersensitivity syndrome is a common problem that consists of a population explosion of the normally benign candida yeast that live in the vagina and elsewhere in the body, coupled with a type of allergic sensitivity to it. Probiotic supplements are widely recommended for this proposed condition because they establish large, healthy populations of friendly bacteria that compete with the candida that is trying to take up residence. However, there is no evidence that yeast hypersensitivity is a common problem, and virtually none that it exists at all.
In one small, 12-week study, Lactobacillus GGfailed to prove more effective than placebo for the treatment of rheumatoid arthritis . 34 Another study failed to find Lactobacillus GGhelpful for dyspepsia (generic stomach pain of unknown origin) in children. 35 A year-long open trial of 150 women failed to find Lactobacillusprobiotics effective for preventing urinary tract infections as compared to cranberry juice or no treatment. 36 Other studies, however, including a large (453-participant), 3-month, double-blind, placebo-controlled study of a special healthy E. coliprobiotic, did find benefits. 37 A substantial study failed to find a mixture of L. casei, L. bulgaricus, and S. thermophilusin yogurt and milk helpful for asthma in children. 38 But, another study found that the combination of a probiotic ( Bifidobacterium breve) and a prebiotic (galacto/fructo-oligosaccharide) may help reduce wheezing in infants with eczema. 39
Probiotics may occasionally cause a temporary increase in digestive gas. But, beyond that, they do not present any known risks for most people. In one trial of 140 healthy infants, formula supplemented with long-chain polyunsaturated fatty acids and probiotics appeared as safe as standard formula, and did not have any effect on infant growth by the end of the 7-month trial. 1 However, individuals who are immunosuppressed could conceivably be at risk for developing a dangerous infection with the probiotic organism itself; at least one person taking immunosuppressive medications has died in this manner. 2 In a detailed review of four studies, researchers concluded that the use probiotics did not benefit patients with severe acute pancreatitis. 3 Furthermore, according to one study, the use of probiotics led to an increased risk of mortality in patients with severe acute pancreatitis, and should, therefore, be avoided under these circumstances. 4
Some probiotic supplements also contain prebiotics like FOS to "feed" the good bacteria. FOS appear to be generally safe. However, they can cause bloating, flatulence, and intestinal discomfort, especially when taken at doses of 15 g or higher daily. People with lactose intolerance may particularly suffer from these side effects.
