Dr. Noe's 10 Steps to Optimal Health
Step 7: Take Vitamin D Daily
Vitamin D is an important nutrient that has wide ranging effects on bodily functions. In addition to its well known impact on lowering the risk of osteoporosis, low vitamin D levels have also been associated with heart attack, cancer, loss of cognitive function, decreased strength, diabetes, arthritis, depression, high blood pressure, metabolic syndrome, epilepsy, polycystic ovaries, decreased immune function, inflammation, and autoimmune diseases such as multiple sclerosis. Furthermore, a study that followed over 13,000 adults for 9 years found that those in the lowest quartile of blood vitamin D levels had a 26% higher risk of death from all causes compared to those in the highest quartile of blood vitamin D levels.
Deficiency of this important nutrient is very common. More than half the world’s population is at risk for vitamin D deficiency, and in the U.S. 36% of healthy young adults are deficient, as well as 80% of Caucasian infants and 52% of adolescent African American and Hispanic children.
While much of the attention with osteoporosis gets paid to calcium
status, most of the evidence identifies vitamin D status as a better
predictor of osteoporosis risk than calcium status (vitamin D determines
how much of the calcium that is consumed actually gets absorbed).
Researchers, in fact, have determined that fracture risk decreases
as vitamin D levels increase throughout the measured range.
There is pretty much universal agreement among medical experts as to the importance of vitamin D, particularly in regard to osteoporosis prevention. There is not agreement, however, on the optimal dose of vitamin D. The RDA is currently set at 600-800 IU daily. With adequate sun exposure, however, it is estimated that the body can produce 10,000-11,000 IU of vitamin D daily. These would be the levels present in the body during the development of the human genome over the last several million years and hence what most likely represents optimum vitamin D dosing. Dietary sources of vitamin D such as milk, however, contain only 100 IU of vitamin D per serving.
The recent release of a new report on vitamin D and calcium by the Institute of Medicine has raised many questions about high doses of vitamin D, however. The authors, as reported in the New York Times and other publications, did not identify any benefit above 800 IU per day, and recommended a maximum dose of 4000 IU per day. While there have now been a number of studies identifying possible benefits of higher doses of vitamin D, such as a possible reduction in the risk of heart disease, colon cancer, breast cancer, and the other diseases listed at the beginning of this article, the authors felt there was insufficient evidence to serve as a basis for the development of the RDA. The RDA is designed to prevent deficiency disease, and not necessarily to promote optimal health.
The authors did not find any evidence of toxicity below 10,000 IU per day of vitamin D. In the words of the authors, “What the data do suggest is that it would be unlikely to observe symptoms of toxicity at intakes below 10,000 IU…” They did, however, find some evidence of possible harm from doses of vitamin D above 4000 IU per day. It is important to note, however, that the authors specifically stated that the data on higher doses of vitamin D (above 4000 IU per day) is sparse and is in no way conclusive either for benefit or for possible harm.
Another factor to consider in interpreting this report is that the authors did not differentiate between synthetic vitamin D2 and natural vitamin D3. While the authors felt that there was no difference between these forms of vitamin D, others disagree.
Lastly, it is important to note that the authors based their recommendations on normal, healthy people. Those with certain health conditions, such as, for example, osteoporosis, may have different requirements.
In the end, this report is in no way a definitive statement on high doses of vitamin D. It does, however, call into question the benefits and risks of doses of vitamin D above 4000 IU per day. To that end, I recommend 2000-4000 IU per day for adults. This is enough to achieve optimum blood vitamin D levels in most adults without exceeding the possible upper safe limit of 4000 IU daily.
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