Health Article: Vitamin D Fact Sheet
Vitamin D is a term for several hormones that are stored mainly in the liver and in fat and muscle tissue. Vitamin D is essential for maintaining healthy bone structure because of its role in the absorption and metabolism of calcium. It is easily absorbed during digestion and is excreted from the body very slowly. It is manufactured in the body from a chemical reaction to the ultraviolet radiation in sunlight and is found in a few food sources, including vitamin D-fortified milk, fatty fish, egg yolk and liver. The AI (adequate intake) level is 200 IU (5 mcg) per day for children and most adults, 400 IU (10 mcg) for people over 50, and 600 IU (15 mcg) for those over 70 who do not have sufficient exposure to sunlight. Some experts believe that many people require supplements to achieve the recommended levels.
Deficiencies of Vitamin D
Deficiencies in vitamin D result in rickets in children and osteomalacia in adults. Both diseases are characterized by a softening of the bones caused by low amounts of calcium and phosphorous. Vitamin D deficiency also increases the risk for hip fractures in post-menopausal women, and is associated with a higher risk for breast cancer, especially in older women, and prostate cancer. There has been some concern that under-exposure to sunlight in older people, particularly if they live in northern regions, may put them at risk for low levels of vitamin D. A 1998 study suggests that vitamin D deficiency may be a significant problem in the general US population, even among younger adults. Experts note that adults may need higher daily amounts than the RDA suggests. Exposure to sunlight for about 15 to 20 minutes at mid-morning or mid-afternoon three times a week is also recommended for most people who live in temperate climates.
Toxicity of Vitamin D
Vitamin D is very toxic in high doses. Infants can be severely affected by daily amounts higher than 1000 IU, which can lead to mental and growth retardation, kidney failure and death. In children and adults, daily amounts over 50,000 IU can cause weakness, anorexia, vomiting, diarrhea and mental changes. Prolonged use of megadoses can cause calcification of soft tissue and life-threatening kidney failure. Low-calcium diets and withdrawal from the vitamin can usually reverse the side effects, except for kidney failure.
IMPORTANT NOTE: One of our readers disagreed with the content of this article. It’s important to be well-informed, so I agree with her suggestion that you should investigate this topic further at http://www.vitamindcouncil.org and any other source you deem appropriate. You should never accept just one source when it comes to your health. As a healthcare writer, I see varying opinions every day on a variety of important health-related topics. It’s up to you to do your own research and decide what’s right for your body.
Photo by Steve Woods
We hope you found this vitamin D health article helpful! You might also be interested in these vitamin-related articles:
- Should You Take Vitamins and Minerals?
- Vitamin A Fact Sheet
- B Vitamins Fact Sheet
- Vitamin C Fact Sheet
- Phytochemicals Fact Sheet
- Drugs That Deplete Vitamins and Minerals
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April 26th, 2008 at 8:02 pm
If you are interested in good information on vitamin d go to http://www.vitamindcouncil.org
April 26th, 2008 at 8:05 pm
Also, how can 50,000 iu at day possibly be toxic?
http://www.vitamindcouncil.org/vitaminDPhysiology.shtml
Cholecalciferol (D3) Forms In The Skin
Studies show that if you go out in the summer sun in your bathing suit until your skin just begins to turn pink, you make between 10,000 and 50,000 units of cholecalciferol (D3) in your skin. Professor Michael Holick of Boston University School of Medicine has studied this extensively and believes a reasonable average of all the studies is 20,000 units. That means a few minutes in the summer sun produces 100 times more vitamin D than the government says you need! As discussed in other pages, this is the single most important fact about vitamin D.
The skin does another amazing thing with cholecalciferol. It prevents vitamin D toxicity. Once you make about 20,000 units, the same ultraviolet light that created cholecalciferol, begins to degrade it. The more you make, the more is destroyed. So a steady state is reached that prevents the skin from making too much cholecalciferol. This is why no one has ever been reported to develop vitamin D toxicity from the sun, though it is possible when taken orally.
April 26th, 2008 at 8:43 pm
In my experience, there are a lot of different opinions about just about any aspect of health care you can think of. Even researchers who are actively studying a subject disagree sometimes with each other.
I’ve placed a note within the article with a link to the site you recommended, along with the suggestion that people should definitely seek out information from multiple sources when it comes to their health.