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National Institute of Health - Strength of Vitamin D Evidence

Clipped Sept 2011 from Medline Plus

Effective for...

  • Treating conditions that cause weak and painful bones (osteomalacia).
  • Low levels of phosphate in the blood (familial hypophosphatemia).
  • Low levels of phosphate in the blood due to a disease called Fanconi syndrome.
  • Psoriasis (with a specialized prescription-only form of vitamin D).
  • Low blood calcium levels because of a low parathyroid thyroid hormone levels.
  • Helping prevent low calcium and bone loss (renal osteodystrophy) in people with kidney failure.
  • Rickets.
  • Vitamin D deficiency.

Likely effective for...

  • Treating osteoporosis (weak bones). Taking a specific form of vitamin D called cholecalciferol (vitamin D3) along with calcium seems to help prevent bone loss and bone breaks.
  • Preventing falls in older people. Researchers noticed that people who don’t have enough vitamin D tend to fall more often than other people.
    They found that taking a vitamin D supplement reduces the risk of falling by up to 22%.
    Higher doses of vitamin D are more effective than lower doses.
    One study found that taking 800 IU of vitamin D reduced the risk of falling, but lower doses didn’t.
  • Also, vitamin D, in combination with calcium, but not calcium alone, may prevent falls by decreasing body sway and blood pressure.
    This combination prevents more falls in women than men.
  • Reducing bone loss in people taking drugs called corticosteroids.

Possibly effective for...

  • Reducing the risk of multiple sclerosis (MS). Studies show taking vitamin D seems to reduce women’s risk of getting MS by up to 40%.
    Taking at least 400 IU per day, the amount typically found in a multivitamin supplement, seems to work the best.
  • Preventing cancer. Some research shows that people who take a high-dose vitamin D supplement plus calcium might have a lower chance of developing cancer of any type.
  • Weight loss. Women taking calcium plus vitamin D are more likely to lose weight and maintain their weight.
    But this benefit is mainly in women who didn’t get enough calcium before they started taking supplements.
  • Flu. Some research in school aged children show that taking a vitamin D supplement during winter might reduce the chance of getting seasonal flu.
  • Reducing the risk of rheumatoid arthritis in older women.
  • Reducing bone loss in women with a condition called hyperparathyroidism.
  • Preventing tooth loss in the elderly.

Possibly ineffective for...

  • Breast cancer. Many studies have looked at whether vitamin D can help prevent breast cancer, but their results have not always agreed.
    The best evidence to date comes from a large study called the Women’s Health Initiative, which found that taking 400 IU of vitamin D and 1000 mg of calcium per day does not seem to lower the chance of getting breast cancer.
    The possibility remains that high doses of vitamin D might lower breast cancer risk in younger women. But the doses needed would be so high that they might not be safe.
  • High blood pressure.
  • Improving muscle strength in older adults.
  • Preventing bone loss in people with kidney transplants.

Insufficient evidence to rate effectiveness for...

  • Heart disease. Research suggests that people with low levels of vitamin D in their blood are much more likely to develop heart disease, including heart failure, than people with higher vitamin D levels. However, taking vitamin D does not seem to extend the life of people with heart failure.
  • High cholesterol. People with lower vitamin D levels seem to be much more likely to have high cholesterol than people with higher vitamin D levels.
    Limited research shows that taking calcium plus vitamin D daily, in combination with a low-calorie diet, significantly raises “good (HDL) cholesterol” and lowers “bad (LDL) cholesterol” in overweight women. But taking calcium plus vitamin D alone, does not reduce LDL cholesterol levels.
  • Gum disease. Higher blood levels of vitamin D seem to be linked with a reduced risk of gum disease in people 50 years of age or older.
    But, this doesn’t seem to be true for adults younger than 50.
  • Diabetes. People with lower vitamin D levels are significantly more likely to have type 2 diabetes compared to people with higher vitamin D levels.
    But, there is no reliable evidence that taking vitamin D supplements can treat or prevent type 2 diabetes.
  • Premenstrual syndrome (PMS). There is some evidence that getting more vitamin D from the diet might help to prevent PMS or reduce symptoms.
    Taking vitamin D supplements might help reduce symptoms but doesn't seem to help prevent PMS.
  • A blood cell disease called myelodysplastic syndrome.
  • A muscle disease called proximal myopathy.
  • Colorectal cancer.
  • Warts.
  • Bronchitis.
  • Asthma.
  • Breathing disorders.
  • Metabolic syndrome.
  • Muscle pain caused by medications called "statins."
  • Vaginal atrophy.
  • Other conditions.

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Note: The above is generally based on < 2,000 IU of vitamin D.

Much higher doses are needed for TREATMENT

See also VitaminDWiki