Adequate amount of vitamin D critical for good health

"Higher vitamin D intake has been associated with lower risks of colorectal, prostate and breast cancer," said J. Lynne Brown, professor of food science. "Higher vitamin D intake also has been associated with a reduced risk of cardiovascular disease, a lower risk of type 1 diabetes and lower risk of autoimmune diseases, such as rheumatoid arthritis, multiple sclerosis and Crohn's disease."

However, the key word is "associated," Brown noted. None of these possible relationships have been proven using the gold standard of clinical trials. The only proven relationship is vitamin D's effect on bone health. Vitamin D is essential for the absorption of calcium from the intestine.

The most natural method for one to get a sufficient amount of vitamin D is sunlight exposure, Brown pointed out. "Fifteen to 30 minutes of sunlight on skin without sunscreen will provide all the daily need of vitamin D," she said. "However, individuals living in the Northern Hemisphere and those of African or East Asian origin who have higher melanin content in their skin may not get enough sun exposure for sufficient vitamin D production."

Brown recommends that these individuals acquire vitamin D through other means, such as vitamin D fortified milk, oily fish, egg yolk or tablet supplements. Still, the Institute of Medicine recently reported that national dietary intake data indicated that most Americans are getting enough vitamin D and set the recommended daily allowance at 600 IU/day for most adults.

Only the elderly might fall short, so the recommended daily allowance for those over age 70 was set at 800 IU/day.

Brown warned that vitamin D deficiency can cause rickets in adolescents and osteopenia and osteoporosis in adults. But it is important, she cautioned, to discuss any concerns about vitamin D deficiency with a primary health-care provider.

"You also should review all potential supplementation with your doctor, because any vitamin supplements can interact adversely with other ongoing drug treatments," she said. If you take supplements, your intake from foods and supplements should not exceed the tolerable upper limit for vitamin D of 4,000 IU per day.

The College of Agricultural Sciences provides publications with pertinent information on vitamin supplementation for health. These fact sheets, authored by Brown, detail the health benefits and risks of vitamin A, D and E supplements.

Provided by Pennsylvania State University