December 6, 2013
Researchers at France’s International Prevention Institute in Lyon analyzed data from several hundred observational studies and clinical trials examining the effects of vitamin D levels on so called non bone health – including links to illness such as cancer, diabetes and cardiovascular disease.
They found that the benefits of high vitamin D levels seen in observational studies were not replicated in randomized trials where participants were given vitamin D to see if it would protect against disease.
Lead researcher, Philippe Autier said “What this discrepancy suggests is that decreases in vitamin D levels are a marker of deteriorating health”. He explained that serious illness like cancer and diabetes may reduce vitamin D concentrations but that does not necessarily mean that raising vitamin D levels would prevent the illness from occurring.
After several years of being touted as the next cure all, opinions on vitamin D are beginning to swing back. You will continue to see more studies published that focus on the limitations of vitamin D, rather than the benefits. Vitamin C had a similar run during the 1970’s fueled by the claims of Linus Pauling. He recommended very large doses of vitamin C for every known disease on the planet. The Linus Pauling Institute, founded by him, has since refuted virtually every one on his claims. Today, vitamin C is recognized as an essential nutrient that is an important antioxidant in the body, but not a cure all. Vitamin D will eventually settle in its’ rightful place as well.
Vitamin D is a hormone, not a vitamin. Our body manufactures it from cholesterol (yes, that horrible fat that must be removed from the body by drugs) when sunlight strikes the skin, making vitamin D3. We also get vitamin D2 and D3 in the diet, primarily from oily fish. D2, and D3 are not really vitamin D, they are precursors and are transported to the liver and converted to 25-hydroxy vitamin D. However, it is still not truly vitamin D but rather a stable form that can be accurately measured on blood tests. Every cell in the body absorbs a little of this form, but much of it remains in circulation in the blood stream. The final conversion to true vitamin D occurs in the kidneys and 1,25-hydroxy vitamin D is produced and functions as a hormone controlling calcium metabolism.
Every cell also can make the final conversion, but that vitamin D remains in the cell where researchers believe it oversees protein replication from DNA. This is where all the questions remain. If vitamin D really acts like a librarian, selecting genetics like books in a library, its function could be vital to disease prevention. Currently, we can not measure vitamin D levels in the cell. In fact, we measure the precursor, 25-hydroxy vitamin D, in the blood because the final form, 1,25 hydroxy vitamin D, is used almost as fast as it is made, so blood levels change by the minute.
THE BOTTOM LINE:
Don’t give up on vitamin D. When the pendulum stops swinging, it will still have value. However, avoid the high level supplementation that has been so popular. Taking 50,000 IU of vitamin D is a massive overdose. It is using a vitamin as a drug. Stick with doses up to 4,000 IU per day unless you have blood work showing a true deficiency.
