Lipid Disorders and Fiber
Water-soluble fiber supplements (such as psyllium, hydroxymethylcellulose and its relatives, and beta glucan from oats) are thought to lower cholesterol, and the FDA has permitted products containing this form of fiber to carry a "heart-healthy" label.31 It must be kept in mind, however, that the bulk of the supporting evidence for this theory comes from studies of oats conducted by manufacturers of oat products.255
Glucomannan, a dietary fiber derived from the tubers of Amorphophallus konjac, has been shown to significantly reduce total and LDL cholesterol levels.
Chitosan, a type of insoluble fiber derived from crustacean shells, has been proposed for reducing cholesterol levels. Research is not yet very encouraging for using chitosan for this purpose.
Effect of Fiber on Lipid Disorders
Experts believe that soluble fiber reduces cholesterol levels by increasing excretion of cholesterol from the digestive tract. This affects two forms of cholesterol: cholesterol from food, and, more importantly, cholesterol from the blood “recycled” by the liver through the intestines.
Research Evidence on Fiber
A comprehensive review combining the results of 14 studies found that glucomannan significantly reduced total and LDL cholesterol levels.289
Many studies indicate that water-soluble fiber supplements lower cholesterol.253,263,291 Keep in mind that the bulk of the supporting evidence for this theory comes from studies of oats conducted by manufacturers of oat products.255
Current evidence suggests that if chitosan does offer any benefits, they are minimal at best.84-92,147,148,187,197,225-226,285
How to Use Fiber
As for soluble fiber, you can incorporate more into your diet by taking supplements and/or increasing your intake of foods that are good sources of soluble fiber, such:
- Oats and barley
- Beans and peas
- Flax seeds
- Fruits such as oranges and apples
- Vegetables such as carrots
A typical dose of oat bran is 5 to 10 g with each meal and at bedtime; psyllium is taken at 10 g with each meal. For improving total and LDL cholesterol, studies have found benefit with beta-glucan at doses ranging from 3 to 15 grams daily. However, benefits have been seen more consistently at the higher end of this range, and one carefully designed study found no benefit at 3 grams daily.33
Beta-glucan products can contain molecules of various average lengths (molecular weight). Some manufacturers claim superior benefits with either high or low molecular weight versions. However, one study failed to find any difference between high molecular weight and low molecular weight beta-glucan for normalizing cholesterol and blood sugar levels.34
Types of Professionals That Would Be Involved with This Treatment
- Integrative MD
- Nutritionist or dietitian
- Naturopathic doctor
Side Effects and Warnings
Because it occurs naturally in foods and is a part of most people's regular diet, fiber is considered to be generally safe at normal amounts. Some people do experience digestive upset (stomach ache, cramps, and/or diarrhea) when they increase their intake of fiber. To avoid this, increase your intake gradually so your body has time to adjust.
There are some theoretical concerns about the use of beta-glucan and its potential effects on the immune system. For more information, see the the Side Effects & Warnings section of the beta glucan article.
- Glore SR, Van Treeck D, Knehans AW, et al. Soluble fiber and serum lipids: a literature review. J Am Diet Assoc. 1994;94:425-436.
- Lovegrove JA, Clohessy A, Milon H, et al. Modest doses of beta-glucan do not reduce concentrations of potentially atherogenic lipoproteins. Am J Clin Nutr. 2000;72:49-55.
- Frank J, Sundberg B, Kamal-Eldin, A et al. Yeast-leavened oat breads with high or low molecular weight beta-glucan do not differ in their effects on blood concentrations of lipids, insulin, or glucose in humans. J Nutr. 2004;134:1384-1388.
- Maezaki Y, Tsuji K, Nakagawa Y, et al. Hypocholesterolemic effect of chitosan in adult males. Biosci Biotechnol Biochem. 1993;57:1439-1444.
- Jing SB, Li L, Ji D, et al. Effect of chitosan on renal function in patients with chronic renal failure. J Pharm Pharmacol. 1997;49:721-723.
- Ormrod D, Holmes CC, Miller TE. Dietary chitosan inhibits hypercholesterolaemia and atherogenesis in the apolipoprotein E-deficient mouse model of atherosclerosis. Atherosclerosis. 1998;138:329-334.
- Deuchi K, Kanauchi O, Imasato Y, et al. Decreasing effect of chitosan on the apparent fat digestibility by rats fed on a high-fat diet. Biosci Biotechnol Biochem. 1994;58:1613-1616.
- Deuchi K, Kanauchi O, Imasato Y, et al. Effect of the viscosity or deacetylation degree of chitosan on fecal fat excreted from rats fed on a high-fat diet. Biosci Biotechnol Biochem. 1995;59:781-785.
- Deuchi K, Kanauchi O, Shizukuishi M, et al. Continuous and massive intake of chitosan affects mineral and fat-soluble vitamin status in rats fed on a high-fat diet. Biosci Biotechnol Biochem. 1995;59:1211-1216.
- Kanauchi O, Deuchi K, Imasato Y, et al. Increasing effect of a chitosan and ascorbic acid mixture on fecal dietary fat excretion. Biosci Biotechnol Biochem. 1994;58:1617-1620.
- Kobayashi T, Otsuka S, Yugari Y. Effect of chitosan on serum and liver cholesterol levels in cholesterol-fed rats. Nutr Rep Int. 1979;19:327-334.
- Ho SC, Tai ES, Eng PH, et al. In the absence of dietary surveillance, chitosan does not reduce plasma lipids or obesity in hypercholesterolaemic obese Asian subjects. Singapore Med J. 2001;42:6-10.
- Tai TS, Sheu WH, Lee WJ, et al. Effect of chitosan on plasma lipoprotein concentrations in type 2 diabetic subjects with hypercholesterolemia [letter]. Diabetes Care. 2000;23:1703-1704.
- Wuolijoki E, Hirvela T, Ylitalo P. Decrease in serum LDL cholesterol with microcrystalline chitosan. Methods Find Exp Clin Pharmacol. 1999;21:357-361.
- Bokura H, Kobayashi S. Chitosan decreases total cholesterol in women: a randomized, double-blind, placebo-controlled trial. Eur J Clin Nutr. 2003;57:721-725.
- Metso S, Ylitalo R, Nikkila M, et al. The effect of long-term microcrystalline chitosan therapy on plasma lipids and glucose concentrations in subjects with increased plasma total cholesterol: a randomised placebo-controlled double-blind crossover trial in healthy men and women. Eur J Clin Pharmacol. 2003 Nov 7. [Epub ahead of print]
- Guha S, Pal SK, Chatterjee N, et al. Effect of chitosan on lipid levels when administered concurrently with atorvastatin—a placebo controlled study. J Indian Med Assoc. 2005;103:418,420.
- Lehtimaki T, Metso S, Ylitalo R, et al. Microcrystalline chitosan is ineffective to decrease plasma lipids in both apolipoprotein E epsilon4 Carriers and non-carriers: a long-term placebo-controlled trial in hypercholesterolaemic volunteers. Basic Clin Pharmacol Toxicol. 2005;97:98-103.
- Queenan KM, Stewart ML, Smith KN, et al. Concentrated oat beta-glucan, a fermentable fiber, lowers serum cholesterol in hypercholesterolemic adults in a randomized controlled trial. Nutr J. 2007 Mar 26. [Epub ahead of print].
- Kelly S, Summerbell C, Brynes A, et al. Wholegrain cereals for coronary heart disease. Cochrane Database Syst Rev. 2007 Apr 18;CD005051.
- Woodgate D, Chan CH, Conquer JA. Cholesterol-lowering ability of a phytostanol softgel supplement in adults with mild to moderate hypercholesterolemia. Lipids. 2006;41:127-132.
- Tapola NS, Lyyra ML, Kolehmainen RM, et al. Safety aspects and cholesterol-lowering efficacy of chitosan tablets. J Am Coll Nutr. 2008;27:22-30.
- Sood N, Baker WL, Coleman CI. Effect of glucomannan on plasma lipid and glucose concentrations, body weight, and blood pressure: systematic review and meta-analysis. Am J Clin Nutr. 2008;88:1167-1175.
- Wei ZH, Wang H, Chen XY, et al. Time- and dose-dependent effect of psyllium on serum lipids in mild-to-moderate hypercholesterolemia: a meta-analysis of controlled clinical trials. Eur J Clin Nutr. 2008 Nov 5.