AMA journal meta-analysis finds vitamin D supplements linked with reduced risk of dying over a six year period
The September 10, 2007 issue of the American Medical Association journal Archives of Internal Medicine published the results of a meta-analysis conducted by Philippe Autier, MD of the International Agency for Research on Cancer in Lyon, France, and Sara Gandini, PhD of the European Institute of Oncology in Milan, which concluded that men and women given vitamin D supplements had a lower risk of dying from any cause over a 5.7 year average follow-up period.
For the review, Drs Autier and Gandini selected 18 randomized, controlled clinical trials involving vitamin D supplementation published prior to November, 2006. The trials included a total of 57,311 participants. Subjects who received vitamin D were given 300 to 2000 international units (averaging 528 IU). Serum vitamin D levels were measured in half of the studies.
There were 4,777 deaths recorded over the follow-up period. Subjects who received vitamin D were found to have a 7 percent lower risk of dying of any cause compared with those who did not receive the vitamin. In those who were tested, blood levels of vitamin D were 1.4 to 5.2 times greater among participants who received vitamin D supplements than in those who did not.
In seeking a explanation for the finding, the authors make note of vitamin D’s ability to inhibit the proliferation of cancer cells, improve blood vessel function, and boost the immune system. They also suggest that the ability shown by statin drugs "to decrease all-cause mortality could partly be due to increases in vitamin D levels they would provoke or through acting as vitamin D analogues on vitamin D receptors."
"The relationship between baseline vitamin D status, dose of vitamin D supplements and total mortality rates remains to be investigated," the authors conclude. "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."
In an accompanying editorial, Edward Giovannucci, MD, ScD, of the Harvard School of Public Health poses provocative questions, such as, "Would even a greater reduction in mortality accrue than that suggested in this meta-analysis if intakes of vitamin D were higher, if compliance was improved, if higher levels of 25-hydroxyvitamin D were attained, and if the duration of supplementation was longer?"
"From a broader public health perspective, the roles of moderate sun exposure, food fortification with vitamin D, and higher-dose vitamin D supplements for adults need to be debated," he concludes.
For the greater part of the 20th century, mainstream medicine was openly hostile to the idea of healthy people taking vitamin supplements. This antivitamin position began to change in the 1990s as irrefutable evidence emerged that supplements could reduce the risk of age-related disease without inducing toxicity.
In the April 9, 1998, issue of the New England Journal of Medicine, an editorial was entitled "Eat Right and Take a Multi-Vitamin." This article was based on studies indicating that certain supplements could reduce homocysteine serum levels and therefore lower heart attack and stroke risk. This was the first time this prestigious medical journal recommended vitamin supplements (Oakley 1998).
An even stronger endorsement for the use of vitamin supplements was in the June 19, 2002, issue of the Journal of the American Medical Association (JAMA).
According to the Harvard University doctors who wrote the JAMA guidelines, it now appears that people who get enough vitamins may be able to prevent such common illnesses as cancer, heart disease, and osteoporosis. The Harvard researchers concluded that suboptimal levels of folic acid and vitamins B6 and B12 are a risk factor for heart disease and colon and breast cancers; low levels of vitamin D contribute to osteoporosis; and inadequate levels of the antioxidant vitamins A, E, and C may increase the risk of cancer and heart disease (Fairfield et al. 2002).
Health-conscious adults regularly monitor their cardiovascular risk factors—such as cholesterol, glucose, and homocysteine—in order to reduce their risk of debilitating cardiovascular disease. Now, intriguing new research suggests that vitamin D may play an essential yet overlooked role in staving off heart disease. Vitamin D deficiency may eventually be added to the list of causative factors that contribute to cardiovascular disorders.
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