During the 1990s dietary supplements
showed promise of fighting many diseases that have plagued us including
cancer, heart disease, stroke and other maladies. Though initially
promising, the studies on efficacy of vitamin supplements have now been
questioned by two long-term trials.
The initial observational studies had suggested that intake or blood levels of vitamins E and C were associated
with reduced risk of
certain cancers. Further, several possibly mechanisms were also put
forth by which antioxidant micronutrients such as vitamin E and vitamin
C may delay various steps in carcinogenesis (the process by which
normal cells are transformed into cancer cells.)
However, there didn't exist a definitive proof that vitamins E and C
can reduce the risk of overall or site-specific cancers. Consequently,
the National Institutes of Health invested hundreds of millions of
dollars in clinical trials involving more than 50,000 participants, to
seek large-scale randomized trial evidence for the supplements'
efficacy in preventing cancers.
The verdict of the trials is pretty much out and the conclusion reached
is that vitamin C, vitamin E and selenium supplements don't reduce the
risk of prostrate cancer and other cancers.
As a result, use of these supplements for the prevention of cancer in
middle-aged and older men may not be effective. The results have been
published in the December 9 edition of the Journal of the American Medical Association
As soon as the results were made known, several experts from the medical industry
called to question the weaknesses inherent in the studies that may
somewhat undercut their conclusions attacking the vitamin supplement's
Drug trials and dietary supplement trials are different. Pharmaceutical drugs
typically are artificial substances not naturally present in our
bodies, whereas vitamins are naturally present in our bodies. So when
subjects consume pharma drugs, it's known what quantity of a substance
is present in their system, but it's a different case with vitamins. As
a result, a baseline exposure that needs to be taken into account to
measure an improvement may be missing from the vitamin studies.
Some experts also suggest that we may still not know whether the
results would be different, if, for instance the dosages had been
higher, or if the subjects were studied for another ten years or so,
Also, that the observed differences between the new studies and
previous supportive studies may be because the effects of nutrients in
the human body are complex and are affected by many variables.
It seems that there's room for the claims of both the studies conducted
and the skepticism surrounding the “sweeping” claims made by the study
Further, it's not just cancer they supposedly help alleviate, rather dietary supplements save billions
in health care costs possibly helping with some of the top issues during the 2009 financial crisis
On the whole it appears that there may be evidence against their
efficacy against cancers, however, more work may still need to be
carried out to reach a truly “definitive” conclusion.