Vitamin D Supplements Don't Help Your Health: Review

[think]

33. The end of the article links to a Harvard article

which includes a section on vitamin D and cancer:

Vitamin D and cancer

Nearly 30 years ago, researchers noticed an intriguing relationship between colon cancer deaths and geographic location: People who lived at higher latitudes, such as in the northern U.S., had higher rates of death from colon cancer than people who live closer to the equator. (26) Many scientific hypotheses about vitamin D and disease stem from studies that have compared solar radiation and disease rates in different countries. These can be a good starting point for other research but don’t provide the most definitive information. The sun’s UVB rays are weaker at higher latitudes, and in turn, people’s vitamin D levels in these high latitude locales tend to be lower. This led to the hypothesis that low vitamin D levels might somehow increase colon cancer risk. (2)

Since then, dozens of studies suggest an association between low vitamin D levels and increased risks of colon and other cancers. (1,27) The evidence is strongest for colorectal cancer, with most (but not all) observational studies finding that the lower the vitamin D levels, the higher the risk of these diseases. (28-38) Vitamin D levels may also predict cancer survival, but evidence for this is still limited. (27) Yet finding such associations does not necessarily mean that taking vitamin D supplements will lower cancer risk.

The VITAL trial will look specifically at whether vitamin D supplements lower cancer risk. It will be years, though, before it releases any results. It could also fail to detect a real benefit of vitamin D, for several reasons: If people in the placebo group decide on their own to take vitamin D supplements, that could minimize any differences between the placebo group and the supplement group; the study may not follow participants for a long enough time to show a cancer prevention benefit; or study participants may be starting supplements too late in life to lower their cancer risk. In the meantime, based on the evidence to date, 16 scientists have circulated a “call for action” on vitamin D and cancer prevention: (27) Given the high rates of vitamin D deficiency in North America, the strong evidence for reduction of osteoporosis and fractures, the potential cancer-fighting benefits of vitamin D, and the low risk of vitamin D supplementation, they recommend widespread vitamin D supplementation of 2000 IU per day. (27)

Read more: vitamin D trials for cancer prevention

From:

http://www.hsph.harvard.edu/nutritionsource/vitamin-d/#vitamin-d-and-cancer

Notice the "Read more" links to Vitamin trials for cancer prevention. From that link there is information regarding early studies, more recent studies, and new on going ones:

Vitamin D Trials for Cancer Prevention

The randomized controlled trial evidence on vitamin D supplementation and cancer prevention has been mixed to date. The Women’s Health Initiative trial, which followed roughly 36,000 women for an average of seven years, failed to find any reduction in colon or breast cancer risk in women who received daily supplements of 400 IU of vitamin D and 1,000 mg of calcium, compared to those who received a placebo. (1, 2) But that study had several limitations, chief among them the relatively low dose of vitamin D. (3, 4) Also, some people in the placebo group decided on their own to take extra calcium and vitamin D supplements, minimizing the differences between the placebo group and the supplement group, and about one third of the women assigned to vitamin D did not take their supplements. (5)


A more recent trial among nearly 1,200 postmenopausal women found significant reductions in overall cancer incidence among those randomized to receive 1,100 IU of vitamin D plus 1400-1500 mg calcium. (6) The Vitamin D and Omega 3 Trial (VITAL) study, which is testing 2,000 IU of vitamin D per day, should offer more answers on the role of vitamin D in cancer prevention, although it could be affected by some of the same limitations as the Women’s Health Initiative.

Entire article:
http://www.hsph.harvard.edu/nutritionsource/vitamin-d-cancer-trials/

The new ongoing study is called Vital and involves studying 20,000 individuals who are given Vitamin D and Omega 3's.

Welcome to the VITAL Study

Welcome to the Web site of the VITamin D and OmegA-3 TriaL (VITAL) at Brigham and Women’s Hospital, an affiliate of Harvard Medical School, in Boston, Massachusetts. VITAL is a research study in 20,000 men and women across the U.S. investigating whether taking daily dietary supplements of vitamin D3 (2000 IU) or omega-3 fatty acids (Omacor® fish oil, 1 gram) reduces the risk for developing cancer, heart disease, and stroke in people who do not have a prior history of these illnesses. Please click on Study Q&A to learn more about this important research endeavor.

http://www.vitalstudy.org/

Will be interesting to see what kind of results come out this study.....