Vitamin D has become very trendy and popular in both popular and medical literature over the last couple years. In fact, there’s growing evidence that indeed this is one vitamin that almost everyone may benefit from. I haven’t taken extra supplements of this before, but after reviewing the latest papers I’m seriously considering taking a special supplement. One of the most convincing angles was its apparent benefits in preventing cancers. Last year Medscape had a nice review of the multiple studies done over the past couple years. (Vitamin D Supplementation and Cancer Prevention) Many studies showed a drop in multiple cancers with higher levels of vitamin D intake. The reverse was also true; those with less vitamin D, especially those in nothern countries with less sunlight to create your natural vitamin D — had higher levels of many types of cancers. Here’s one synopsis:

Epidemiologic studies, both prospective and retrospective, have shown that individuals who have serum 25-hydroxyvitamin D levels less than 20 ng/mL have an associated 30% to 50% greater risk of colon, prostate, and breast cancer as well as a higher mortality rate from these cancers. In addition, analysis of the Women’s Health Initiative showed that women who had a serum 25-hydroxyvitamin D level less than 12 ng/mL (30 nmol/L) had a 253% increase in the risk of colorectal cancer over an 8-year follow-up period.

This article is a bit technical but there are other websites which repeat the same encouraging findings. I found another good review from New England Journal of Medicine (free in China!) There have been many fads about vitamins and supplements, but this one may actually be useful. By the way, an average multivitamin usually only has 400 IU of vitamin D, which apparently isn’t enough to get the most protection. But don’t take too much, as super-high supplement doses can cause problems. I hear the Canadian health department now recommends all to take 1000 IU supplement daily; this article recommends 2000. Many women taking calcium supplements are probably getting 400-800IU extra in their combo pills; that may be good for bones but higher doses may be even better to prevent cancer. Here are more specifics:

Reports have shown that a large percentage of our population may have serum vitamin D concentrations that are considered suboptimal. Obtaining adequate amounts of vitamin D is important not only for bone health but also for decreasing the risk for several other diseases and conditions, including cancer. Data support the justification for supplementing vitamin D3 2000 IU/d in most adults to decrease the risk for several types of cancers and other conditions. Vitamin D3 is relatively inexpensive and can be found as an over-the-counter product in most pharmacies.

Yet another paper last year in Archives of Internal Medicine, a prospective observational study of 0ver 13,000 people, found that “those in the lowest quartile (25[OH]D levels <17.8 ng/mL) had a 26% increased rate of all-cause mortality (mortality rate ratio, 1.26; 95% CI, 1.08-1.46) and a population attributable risk of 3.1%. The adjusted models of CVD and cancer mortality revealed a higher risk, which was not statistically significant.”

The Bottom Line

It still isn’t rock-solid sure that everyone may benefit from a supplement; certainly children should already be taking their vitamin D supplements as recommended by their doctor; and perhaps most northern people and especially women should consider a supplement. Perhaps we need to do more routine vitamin D blood tests to see people’s vitamin D levels, and supplement only those whose levels are low. But it is very common to have low levels; it’s estimated that 41% of men and 53% of women in America have a deficiency and would benefit from supplements.