TUESDAY September 11, 2007 (Foodconsumer.org) -- Vitamin D has been known to provide a wide variety of health benefits.   A review article suggests that taking vitamin D supplements or by all means maintain a high level of vitamin D in the blood may significantly reduce risk of death from any cause.

The review study of 18 previous studies found those who had high levels of vitamin D in their blood or took vitamin D supplements were 7 percent less likely to die from any cause compared to those who did not take supplements over an average six years of follow-up.

Early studies already showed deficiencies in vitamin D might be associated with a higher risk of death from caner, heart disease and diabetes-illnesses, which overall are responsible for 60 to 70 percent of deaths in developed countries.

Because of this, Philippe Autier, M.D., of the International Agency for Research on Cancer, Lyon, France, and Sara Gandini, Ph.D., of the European Institute of Oncology in Milan, Italy hypothesized that high vitamin D levels or taking vitamin D supplements should reduce the overall death risk.

“If the associations made between vitamin D and these conditions were consistent, then interventions effectively strengthening vitamin D status should result in reduced total mortality,” the authors write.

In the study, which appears in the September 10 issue of Archives of Internal Medicine, one of the JAMA/Archives journals, the researchers meta-analyzed data from 18 separate trials that included 57,000 participants and doses of vitamin D used ranged from 300 to 2000 international Units with an average dose of 528 IU.

Vitamin D is naturally present only in a few foods including eggs and oily fish.   Humans can synthesize vitamin D by exposure to sunshine.   Vitamin D, often in form of vitamin D2, is sold in supplements or used to fortify certain foods such as milk.   But the dose in supplements is no more than 400 to 600 IU.

Autier and Gandini found individuals who took vitamin D had a 7 percent lower risk of death than those who did not.   The data from nine trials that collected and analyzed serum vitamin D levels showed that those who took supplements had an average 1.4 to 5.2 -fold higher blood level of vitamin D than those who did not.

“Mechanisms by which vitamin D supplementation would decrease all-cause mortality are not clear,” write the authors who speculate that vitamin D could inhibit cancer cell proliferation and or boost the function of blood vessels or the immune system.

The researchers conclude "the intake of ordinary doses of vitamin D supplements seems to be associated with decreases in total mortality rates.”  

They write “The relationship between baseline vitamin D status, dose of vitamin D supplements and total mortality rates remains to be investigated. Population-based, placebo-controlled randomized trials in people 50 years or older for at least six years with total mortality as the main end point should be organized to confirm these findings.”

The meta-analysis “adds a new chapter in the accumulating evidence for a beneficial role of vitamin D on health,” Edward Giovannucci, M.D., Sc.D., of the Harvard School of Public Health, Boston says in an accompanying editorial.   “Research on vitamin D should be continued to clearly elucidate the specific benefits and optimal intakes and levels of vitamin D.”

The current recommended daily allowance for adults is 200 IU, which is way too low to have a protective effect against certain diseases such as cancer and heart disease, according to some experts who urged the government to raise the recommendation to 2000 IU.   Studies did not show any adverse effect of daily intake of up to 10,000 IUs of vitamin D.