Share

Vitamin D Contributions by ColleenO

Article Revisions

Vitamin D plays a number of roles in the body, some of which are just now being discovered and confirmed. Its exact role in preventing or treating hypertension is not immediately clear. One possibility is that vitamin D helps enhance our body's levels of calcium, helping prevent calcium deficiency, which has been linked to the development of hypertension.29,30,58 (See the article on Calcium and Hypertension for more information.)

... (more)

Vitamin D, sometimes called "the sun vitamin" because our bodies use sun exposure to manufacture vitamin D, might prevent the development of hypertension. Vitamin D is also sometimes recommended as a treatment for hypertension that has already developed, though research evidence for this use is not strong. This vitamin D does have many other potential health benefits, and most people are deficient, so it may be worth taking as a supplement and/or making sure you get modest sun exposure (about 15 minutes per day of legs and arms exposed to the sun).

A common blood test can help you and your healthcare provider know your vitamin D status. If you are elderly, spend most of your time indoors, have darker skin, and/or live in northern latitudes, you are more likely to be vitamin D deficient.

... (more)

Safety Issues

When taken at recommended dosages, vitamin D appears to be safe. However, when used at considerable excess, vitamin D can build up in the body and cause toxic symptoms. At an intake level of about 40,000 IU daily (about 100 times the recommended daily intake) vitamin D can cause dangerous elevations in blood calcium levels. 1 Doses five times higher than this were consumed by a few individuals due to a manufacturing error; the resulting toxicity was severe and may have caused death in one individual. 2 However, short of these vastly excessive dosages, it is not clear at what level vitamin D becomes toxic.

According to updated recommendations from the Institute of Medicine,44 the safe upper limits (UL) for vitamin D daily intake are as follows:

  • Children and Infants:
    • 0-6 months: 1,000 IU
    • 6-12 months: 1,500 IU
    • 1-3 years: 2,500 IU
    • 4-8 years: 3,000 IU
    • 9-18 years: 4,000 IU
  • Adults:
    • 19-70 years: 4,000 IU
    • 71 years and older: 4,000 IU
  • Pregnant/lactating women:
    • 14-50 years: 4,000 IU

There is no disagreement that people with sarcoidosis or hyperparathyroidism should never take vitamin D without first consulting a physician.

Taking vitamin D and calcium supplements might interfere with some of the effects of drugs in the calcium-channel blocker family. 3 It is very important that you consult your physician before trying this combination.

The combination of calcium, vitamin D, and thiazide diuretics could potentially lead to excessive calcium levels in the body. 4 If you are taking thiazide diuretics, you should consult with a physician about the right doses of vitamin D and calcium for you.

Interactions You Should Know About

  • You may need extra vitamin D if you are taking antiseizure drugs, such as:
    • Phenobarbital
    • Primidone (Mysoline)
    • Valproic acid (Depakene)
    • Phenytoin (Dilantin)
    • Corticosteroids
    • Cimetidine (Tagamet)
    • Heparin
    • Isoniazid (INH)
    • Rifampin
  • If you are taking calcium-channel blockers , do not take high-dose vitamin D (with calcium) except under physician supervision.
  • If you are taking thiazide diuretics , do not take calcium and vitamin D supplements unless under a doctor's supervision.
... (more)

Safety Issues

When taken at recommended dosages, vitamin D appears to be safe. However, when used at considerable excess, vitamin D can build up in the body and cause toxic symptoms. At an intake level of about 40,000 IU daily (about 100 times the recommended daily intake) vitamin D can cause dangerous elevations in blood calcium levels. 1 Doses five times higher than this were consumed by a few individuals due to a manufacturing error; the resulting toxicity was severe and may have caused death in one individual. 2 However, short of these vastly excessive dosages, it is not clear at what level vitamin D becomes toxic.

According to updated recommendations from the Institute of Medicine,44 the safe upper limits (UL) for vitamin D daily intake are as follows:

  • Children and Infants:
    • 0-6 months: 1,000 IU
    • 6-12 months: 1,500 IU
    • 1-3 years: 2,500 IU
    • 4-8 years: 3,000 IU
    • 9-18 years: 4,000 IU
  • Adults:
    • 19-70 years: 4,000 IU
    • 71 years and older: 4,000 IU
  • Pregnant/lactating women:
    • 14-50 years: 4,000 IU

There is no disagreement that people with sarcoidosis or hyperparathyroidism should never take vitamin D without first consulting a physician.

Taking vitamin D and calcium supplements might interfere with some of the effects of drugs in the calcium-channel blocker family. 3 It is very important that you consult your physician before trying this combination.

The combination of calcium, vitamin D, and thiazide diuretics could potentially lead to excessive calcium levels in the body. 4 If you are taking thiazide diuretics, you should consult with a physician about the right doses of vitamin D and calcium for you.

Interactions You Should Know About

  • You may need extra vitamin D if you are taking antiseizure drugs, such as:
    • Phenobarbital
    • Primidone (Mysoline)
    • Valproic acid (Depakene)
    • Phenytoin (Dilantin)
    • Corticosteroids
    • Cimetidine (Tagamet)
    • Heparin
    • Isoniazid (INH)
    • Rifampin
  • If you are taking calcium-channel blockers , do not take high-dose vitamin D (with calcium) except under physician supervision.
  • If you are taking thiazide diuretics , do not take calcium and vitamin D supplements unless under a doctor's supervision.
... (more)
  1. Cappuccio FP, Elliott P, Allender PS, et al. Epidemiologic association between dietary calcium intake and blood pressure: a meta-analysis of published data. Am J Epidemiol. 1995;142:935-945.
  2. Van Leer EM, Seidell JC, Kromhout D. Dietary calcium, potassium, magnesium and blood pressure in the Netherlands. Int J Epidemiol. 1995;24:1117-1123.
  3. Institute of Medicine. Report Brief: Dietary Reference Intakes for Calcium and Vitamin D. Released November 30, 2010. Accessed at the IOM Web site: http://www.iom.edu/Reports/2010/Dietary-Reference-Intakes-for-Calcium-and-Vitamin-D/Report-Brief.aspx?page=1
  4. Fuller KE, Casparian JM. Vitamin D: balancing cutaneous and systematic considerations. South Med J. 2001;94:58-64.
  5. Rostand SG. Ultraviolet light may contribute to geographic and racial blood pressure differences. Hypertension. 1997;30(2 pt 1):150-156.
  6. Krause R, Buhring M, Hopfenmuller W, et al. Ultraviolet B and blood pressure [letter]. Lancet. 1998;352:709-710.
  7. Scragg R. Sunlight, vitamin D, and cardiovascular disease. In: Crass MF II, Avioli LV, eds. Calcium Regulating Hormones and Cardiovascular Function. Boca Raton, FL: CRC Press; 1995:213-237.
  8. O'Connell TD, Simpson RU. 1,25-dihydroxyvitamin D3 and cardiac muscle structure and function. In: Crass MF II, Avioli LV, eds. Calcium-Regulating Hormones and Cardiovascular Function. Boca Raton, FL: CRC Press; 1995:191-211.
  9. Porsti I, Makynen H. Dietary calcium intake: effects on central blood pressure control. Semin Nephrol. 1995;15:550-563.
  10. Margolis KL, Ray RM, Van Horn L, et al. Effect of calcium and vitamin D supplementation on blood pressure: the Women's Health Initiative Randomized Trial. Hypertension. 2008;52:847-855.
... (more)

Vitamin D plays a number of roles in the body, some of which are just now being discovered and confirmed. Its exact role in preventing or treating hypertension is not immediately clear. One possibility is that vitamin D helps enhance our body's levels of calcium, helping prevent calcium deficiency, which has been linked to the development of hypertension.29,30,58 (See the article on Calcium and Hypertension for more information.)

... (more)

Vitamin D, sometimes called "the sun vitamin" because our bodies use sun exposure to manufacture vitamin D, might prevent the development of hypertension, but it does not necessarily help treat . Vitamin D is also sometimes recommended as a treatment for hypertension that has already developed. However, , though research evidence for this use is not strong. This vitamin D does have many other potential health benefits, and most peoler li. people are deficient, so it may be worth taking as a supplement and/or making sure you get modest sun exposure (about 15 minutes per day of legs and arms exposed to the sun).

A common blood test can help you and your healthcare provider know your vitamin D status. If you are elderly, spend most of your time indoors, have darker skin, and/or live in northern latitudes, you are more likely to be vitamin D deficient.

... (more)

A common blood test can help you and your healthcare provider know your vitamin D status. If you are elderly, spend most of your time indoors, have darker skin, and/or live in northern latitudes, you are more likely to be vitamin D deficient.

Although vitamin D is found in some foods, the best source is sun exposure (about 15 minutes per day of arms and legs exposed to the sun) and supplements.

Vitamin D is typically taken at doses between the Recommended Daily Allowance (RDA) and the Upper Level Intake (UL), the upper limit of what is considered safe. (See below.) Therapeutic doses are usually closer to the UL. These recommendations were updated in 2010 by the Institute of Medicine, and they vary for people of different ages and pregnancy/lactation status. Many health experts now recommended that people who are vitamin D deficient take daily doses closer to the UL, because lower doses might not correct a deficiency.

The Institute of Medicine's updated (November 2010) recommendations for daily intake of vitamin D44 are as follows. The first number is the Recommended Dietary Allowance (RDA), and the second number is the Upper Intake Level (UL), the highest daily dose that is considered safe:

  • Children and Infants:
    • 0-6 months: no RDA/1,000 IU
    • 6-12 months: no RDA/1,500 IU
    • 1-3 years: 600 IU/2,500 IU
    • 4-8 years: 600 IU/3,000 IU
    • 9-18 years: 600 IU/4,000 IU
  • Adults:
    • 19-70 years: 600 IU/4,000 IU
    • 71 years and older: 800 IU/4,000 IU
  • Pregnant/lactating women:
    • 14-50 years: 600 IU/4,000 IU

Vitamin D is a fat-soluble vitamin, which means that your body can store it in your tissues. If you wish to take higher doses of of vitamin D intake, it is recommended that you consult with a physician or other qualified health professional, such as a naturopathic doctor (see Side Effects & Warnings for more information).

... (more)
  • Naturopathic doctor
  • Nutritionist or dietitian
  • Physician, especially an integrative MD
  • Chiropractor
... (more)

Although vitamin D is found in some foods, the best source is sun exposure (about 15 minutes per day of arms and legs exposed to the sun) and supplements.

Vitamin D is typically taken at doses between the Recommended Daily Allowance (RDA) and the Upper Level Intake (UL), the upper limit of what is considered safe. (See below.) Therapeutic doses are usually closer to the UL. These recommendations were updated in 2010 by the Institute of Medicine, and they vary for people of different ages and pregnancy/lactation status. Many health experts now recommended that people who are vitamin D deficient take daily doses closer to the UL, because lower doses might not correct a deficiency.

The Institute of Medicine's updated (November 2010) recommendations for daily intake of vitamin D44 are as follows. The first number is the Recommended Dietary Allowance (RDA), and the second number is the Upper Intake Level (UL), the highest daily dose that is considered safe:

  • Children and Infants:
    • 0-6 months: no RDA/1,000 IU
    • 6-12 months: no RDA/1,500 IU
    • 1-3 years: 600 IU/2,500 IU
    • 4-8 years: 600 IU/3,000 IU
    • 9-18 years: 600 IU/4,000 IU
  • Adults:
    • 19-70 years: 600 IU/4,000 IU
    • 71 years and older: 800 IU/4,000 IU
  • Pregnant/lactating women:
    • 14-50 years: 600 IU/4,000 IU

Vitamin D is a fat-soluble vitamin, which means that your body can store it in your tissues. If you wish to take higher doses of of vitamin D intake, it is recommended that you consult with a physician or other qualified health professional, such as a naturopathic doctor (see Side Effects & Warnings for more information).

... (more)
  1. Cappuccio FP, Elliott P, Allender PS, et al. Epidemiologic association between dietary calcium intake and blood pressure: a meta-analysis of published data. Am J Epidemiol. 1995;142:935-945.
  2. Van Leer EM, Seidell JC, Kromhout D. Dietary calcium, potassium, magnesium and blood pressure in the Netherlands. Int J Epidemiol. 1995;24:1117-1123.
  3. Institute of Medicine. Report Brief: Dietary Reference Intakes for Calcium and Vitamin D. Released November 30, 2010. Accessed at the IOM Web site: http://www.iom.edu/Reports/2010/Dietary-Reference-Intakes-for-Calcium-and-Vitamin-D/Report-Brief.aspx?page=1
  4. Fuller KE, Casparian JM. Vitamin D: balancing cutaneous and systematic considerations. South Med J. 2001;94:58-64.
  5. Rostand SG. Ultraviolet light may contribute to geographic and racial blood pressure differences. Hypertension. 1997;30(2 pt 1):150-156.
  6. Krause R, Buhring M, Hopfenmuller W, et al. Ultraviolet B and blood pressure [letter]. Lancet. 1998;352:709-710.
  7. Scragg R. Sunlight, vitamin D, and cardiovascular disease. In: Crass MF II, Avioli LV, eds. Calcium Regulating Hormones and Cardiovascular Function. Boca Raton, FL: CRC Press; 1995:213-237.
  8. O'Connell TD, Simpson RU. 1,25-dihydroxyvitamin D3 and cardiac muscle structure and function. In: Crass MF II, Avioli LV, eds. Calcium-Regulating Hormones and Cardiovascular Function. Boca Raton, FL: CRC Press; 1995:191-211.
  9. Porsti I, Makynen H. Dietary calcium intake: effects on central blood pressure control. Semin Nephrol. 1995;15:550-563.
  10. Margolis KL, Ray RM, Van Horn L, et al. Effect of calcium and vitamin D supplementation on blood pressure: the Women's Health Initiative Randomized Trial. Hypertension. 2008;52:847-855.
... (more)

Although vitamin D is found in some foods, the best source is sun exposure (about 15 minutes per day of arms and legs exposed to the sun) and supplements.

Vitamin D is typically taken at doses between the Recommended Daily Allowance (RDA) and the Upper Level Intake (UL), the upper limit of what is considered safe. (See below.) Therapeutic doses are usually closer to the UL. These recommendations were updated in 2010 by the Institute of Medicine, and they vary for people of different ages and pregnancy/lactation status. Many health experts now recommended that people who are vitamin D deficient take daily doses closer to the UL, because lower doses might not correct a deficiency.

The Institute of Medicine's updated (November 2010) recommendations for daily intake of vitamin D44 are as follows. The first number is the Recommended Dietary Allowance (RDA), and the second number is the Upper Intake Level (UL), the highest daily dose that is considered safe:

  • Children and Infants:
    • 0-6 months: no RDA/1,000 IU
    • 6-12 months: no RDA/1,500 IU
    • 1-3 years: 600 IU/2,500 IU
    • 4-8 years: 600 IU/3,000 IU
    • 9-18 years: 600 IU/4,000 IU
  • Adults:
    • 19-70 years: 600 IU/4,000 IU
    • 71 years and older: 800 IU/4,000 IU
  • Pregnant/lactating women:
    • 14-50 years: 600 IU/4,000 IU

Vitamin D is a fat-soluble vitamin, which means that your body can store it in your tissues. If you wish to take higher doses of of vitamin D intake, it is recommended that you consult with a physician or other qualified health professional, such as a naturopathic doctor (see Side Effects & Warnings for more information).

... (more)
  1. Institute of Medicine. Report Brief: Dietary Reference Intakes for Calcium and Vitamin D. Released November 30, 2010. Accessed at the IOM Web site: http://www.iom.edu/Reports/2010/Dietary-Reference-Intakes-for-Calcium-and-Vitamin-D/Report-Brief.aspx?page=1
... (more)

Safety Issues

When taken at recommended dosages, vitamin D appears to be safe. However, when used at considerable excess, vitamin D can build up in the body and cause toxic symptoms. At an intake level of about 40,000 IU daily (about 100 times the recommended daily intake) vitamin D can cause dangerous elevations in blood calcium levels. 1 Doses five times higher than this were consumed by a few individuals due to a manufacturing error; the resulting toxicity was severe and may have caused death in one individual. 2 However, short of these vastly excessive dosages, it is not clear at what level vitamin D becomes toxic. The official

According to updated recommendations from the Institute of Medicine,44 the safe upper limits (UL) for vitamin D daily intake are as follows: 3

  • Children and Infants:
    • 0-6 months: 1,000 IU
    • 6-12 months: 1,
    000 IU (25 mcg)
  • Males and females 1 year and older: 2,000 IU (50 mcg)
  • Pregnant and nursing women: 2,000 IU (50 mcg)

Note, however, that some authorities believe these upper limits have been set a bit too low. 4 Their arguments closely parallel those discussed in the Requirements/Sources section regarding nutritional needs.

    • 500 IU
    • 1-3 years: 2,500 IU
    • 4-8 years: 3,000 IU
    • 9-18 years: 4,000 IU
  • Adults:
    • 19-70 years: 4,000 IU
    • 71 years and older: 4,000 IU
  • Pregnant/lactating women:
    • 14-50 years: 4,000 IU

There is no disagreement that people with sarcoidosis or hyperparathyroidism should never take vitamin D without first consulting a physician.

Taking vitamin D and calcium supplements might interfere with some of the effects of drugs in the calcium-channel blocker family. 5 3 It is very important that you consult your physician before trying this combination.

The combination of calcium, vitamin D, and thiazide diuretics could potentially lead to excessive calcium levels in the body. 6 4 If you are taking thiazide diuretics, you should consult with a physician about the right doses of vitamin D and calcium for you.

Interactions You Should Know About

  • You may need extra vitamin D if you are taking antiseizure drugs, such as:
    • Phenobarbital
    • Primidone (Mysoline)
    • Valproic acid (Depakene)
    • Phenytoin (Dilantin)
    • Corticosteroids
    • Cimetidine (Tagamet)
    • Heparin
    • Isoniazid (INH)
    • Rifampin
  • If you are taking calcium-channel blockers , do not take high-dose vitamin D (with calcium) except under physician supervision.
  • If you are taking thiazide diuretics , do not take calcium and vitamin D supplements unless under a doctor's supervision.
... (more)

For therapeutic purposes, vitamin Vitamin D is typically taken at doses between the Recommended Daily Allowance (RDA) and the Upper Level Intake (UL), the upper limit of what is considered safe. These numbers were recently updated Therapeutic doses are usually closer to the UL. These recommendations were updated in 2010 by the Institute of Medicine, and they vary for people of different ages and pregnancy/lactation status. See Requirements/Sources for more details.

Sometimes, vitamin D is recommended or prescribed at doses that exceed what is typically considered "safe." In these cases, physician supervision is recommended. (See Side Effects & Warnings for more information.)

... (more)

Vitamin D is typically taken at the nutritional doses described in Requirements/Sources (and sometimes in even higher amounts). If you wish to exceed nutritional levels of vitamin D intakedoses between the Recommended Daily Allowance (RDA) and the Upper Level Intake (UL), the upper limit of what is considered safe. Therapeutic doses are usually closer to the UL. These recommendations were updated in 2010 by the Institute of Medicine, and they vary for people of different ages and pregnancy/lactation status. See Requirements/Sources for more details.

Sometimes, vitamin D is recommended or prescribed at doses that exceed what is typically considered "safe." In these cases, physician supervision is recommended (see Safety Issues ). (See Side Effects & Warnings for more information.)

... (more)

As with vitamin A , dosages of vitamin D are often expressed in terms of international units (IU) rather than milligrams. The Institute of Medicine's updated (November 2010) recommendations for daily intake of vitamin D44 are as follows. The first number is the Recommended Dietary Allowance (RDA), and the second number is the Upper Intake Level (UL), the highest daily dose that is considered safe:

  • Children and Infants:
    • 0-6 months: no RDA/1,000 IU
    • 6-12 months: no RDA/1,500 IU
    • 1-3 years: 600 IU/2,500 IU
    • 4-8 years: 600 IU/3,000 IU
    • 9-18 years: 600 IU/4,000 IU
  • Adults:
    • 19-70 years: 600 IU/4,000 IU
    • 71 years and older: 800 IU/4,000 IU
  • Pregnant/lactating women:
    • 14-50 years: 600 IU/4,000 IU

These recommendations were updated because growing evidence suggests that prior recommendations may have been too low. In a study of military personnel in submarines, use of 400 IU of vitamin D daily was inadequate to maintain bone health, while six days of sun exposure proved capable of supplying enough vitamin D for 49 sunless days. 1 In addition, a study of veiled Islamic women living in Denmark found that 600 IU of vitamin D daily was insufficient to raise vitamin D levels in the blood to normal levels. 2 The authors of this study recommend that sun-deprived individuals should receive 1,000 IU of vitamin D daily.

There is very little vitamin D found naturally in the foods we eat (the best sources are coldwater fish). In many countries, vitamin D is added to milk and other foods like breakfast cereals and margarine, contributing to our daily intake.

As indicated by the study of submarine personnel noted above, by far the best source of vitamin D is sunlight. However, current recommendations which stress sun avoidance and the use of sunblock may have the unintended effect of increasing the prevalence of vitamin D deficiency. Severe vitamin D deficiency was common in England in the 1800s due to coal smoke obscuring the sun. During that time, cod liver oil, which is high in vitamin D, became popular as a supplement for children to help prevent rickets. (Rickets is a disease caused by vitamin D deficiency in which developing bones soften and curve because they aren't receiving enough calcium.)

Vitamin D deficiency is known to occur today in the elderly (who often receive less sun exposure) as well as in people who live in northern latitudes and don't drink vitamin D-enriched milk. 3 The consequences of this deficiency may be increased risk of hypertension , osteoporosis , and several forms of cancer . 4 Additionally, phenytoin (Dilantin) , primidone (Mysoline) , and phenobarbital for seizures; corticosteroids ; cimetidine (Tagamet) for ulcers; the blood-thinning drug heparin ; and the antituberculosis drugs isoniazid (INH) and rifampin may interfere with vitamin D absorption or activity. 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

... (more)
Edited Vitamin D Overview: References 8 years ago
  1. Institute of Medicine. Report Brief: Dietary Reference Intakes for Calcium and Vitamin D. Released November 30, 2010. Accessed at the IOM Web site: http://www.iom.edu/Reports/2010/Dietary-Reference-Intakes-for-Calcium-and-Vitamin-D/Report-Brief.aspx?page=1
  2. Fuller KE, Casparian JM. Vitamin D: balancing cutaneous and systematic considerations. South Med J. 2001;94:58-64.
  3. Rostand SG. Ultraviolet light may contribute to geographic and racial blood pressure differences. Hypertension. 1997;30(2 pt 1):150-156.
  4. Krause R, Buhring M, Hopfenmuller W, et al. Ultraviolet B and blood pressure [letter]. Lancet. 1998;352:709-710.
  5. Scragg R. Sunlight, vitamin D, and cardiovascular disease. In: Crass MF II, Avioli LV, eds. Calcium Regulating Hormones and Cardiovascular Function. Boca Raton, FL: CRC Press; 1995:213-237.
  6. O'Connell TD, Simpson RU. 1,25-dihydroxyvitamin D3 and cardiac muscle structure and function. In: Crass MF II, Avioli LV, eds. Calcium-Regulating Hormones and Cardiovascular Function. Boca Raton, FL: CRC Press; 1995:191-211.
... (more)

As with vitamin A , dosages of vitamin D are often expressed in terms of international units (IU) rather than milligrams. The official US and Canadian Institute of Medicine's updated (November 2010) recommendations for daily intake of vitamin D44 are as follows. The first number is the Recommended Dietary Allowance (RDA), and the second number is the Upper Intake Level (UL), the highest daily dose that is considered safe:

  • Children and Infants:
    • 0-
    12
    • 6 months:
    200 IU (5 mcg)Males and females:
    • 1-50 years: 200 IU (5 mcg)
    • 51–70 years: 400 IU (10 mcg)
    • no RDA/1,000 IU
    • 6-12 months: no RDA/1,500 IU
    • 1-3 years: 600 IU/2,500 IU
    • 4-8 years: 600 IU/3,000 IU
    • 9-18 years: 600 IU/4,000 IU
  • Adults:
    • 19-70 years: 600 IU/4,000 IU
    • 71 years and older: 600 IU (15 mcg)
  • Pregnant women: 200 IU (5 mcg)
  • Nursing women: 200 IU (5 mcg)
However,
    • 800 IU/4,000 IU
  • Pregnant/lactating women:
    • 14-50 years: 600 IU/4,000 IU

These recommendations were updated because growing evidence suggests that these prior recommendations may be have been too low. In a study of military personnel in submarines, use of 400 IU of vitamin D daily was inadequate to maintain bone health, while six days of sun exposure proved capable of supplying enough vitamin D for 49 sunless days. 1 In addition, a study of veiled Islamic women living in Denmark found that 600 IU of vitamin D daily was insufficient to raise vitamin D levels in the blood to normal levels. 2 The authors of this study recommend that sun-deprived individuals should receive 1,000 IU of vitamin D daily.

There is very little vitamin D found naturally in the foods we eat (the best sources are coldwater fish). In many countries, vitamin D is added to milk and other foods like breakfast cereals and margarine, contributing to our daily intake.

As indicated by the study of submarine personnel noted above, by far the best source of vitamin D is sunlight. However, current recommendations which stress sun avoidance and the use of sunblock may have the unintended effect of increasing the prevalence of vitamin D deficiency. Severe vitamin D deficiency was common in England in the 1800s due to coal smoke obscuring the sun. During that time, cod liver oil, which is high in vitamin D, became popular as a supplement for children to help prevent rickets. (Rickets is a disease caused by vitamin D deficiency in which developing bones soften and curve because they aren't receiving enough calcium.)

Vitamin D deficiency is known to occur today in the elderly (who often receive less sun exposure) as well as in people who live in northern latitudes and don't drink vitamin D-enriched milk. 3 The consequences of this deficiency may be increased risk of hypertension , osteoporosis , and several forms of cancer . 4 Additionally, phenytoin (Dilantin) , primidone (Mysoline) , and phenobarbital for seizures; corticosteroids ; cimetidine (Tagamet) for ulcers; the blood-thinning drug heparin ; and the antituberculosis drugs isoniazid (INH) and rifampin may interfere with vitamin D absorption or activity. 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

... (more)

Enter section content... Vitamin D plays a number of roles in the body, some of which are just now being discovered and confirmed. Its exact role in preventing or treating hypertension is not immediately clear. One possibility is that vitamin D helps enhance our body's levels of calcium, helping prevent calcium deficiency, which has been linked to the development of hypertension.29,30,58 (See the article on Calcium and Hypertension for more information.)

... (more)