The findings of one
of the largest placebo-controlled trials into the beneficial effects of
vitamin D and fish oil ever conducted have just been published and, despite
some hyperbolic media releases, the overall results found both supplements were
no better than the placebo in lowering incidences of cancer or cardiovascular
The rigorous and well designed trial started with over 25,000 healthy subjects
over the age of 50. Each participant was randomly, and blindly, assigned one of
four daily combinations: 2,000 units of vitamin D and 1 gram of fish oil, the
vitamin D and a placebo, the fish oil and a placebo, or two placebos.
The study followed the subjects for over five years,
tracking the onset of major cardiovascular events or invasive cancers, and the
results will certainly disappoint anyone with a stake in these supplements. The
conclusion of the
omega-3 study was, "Supplementa
However, digging
into the more granular detail in the study reveals some specific findings that
some researchers are pushing to the foreground. JoAnn Manson, one of the key
researchers on the study, focuses on two specific secondary datapoints
suggesting, "omega-3s were associated with a reduction in risk of heart
attacks across our study population, especially among participants who had
lower than average fish intake," and vitamin D could be associated with
lower rates of cancer deaths starting from one to two years into the study.tion
with n−3 fatty acids did not result in a lower incidence of major
cardiovascular events or cancer than placebo." The conclusion of the
vitamin D study was pretty much the same, "Supplementation with vitamin D
did not result in a lower incidence of invasive cancer or cardiovascular events
than placebo."In an editorial accompanying the dual studies,
published in the New England Journal of Medicine, John F. Keaney and
Clifford J. Rosen suggest "these "positive" results need to be
interpreted with caution. As well as noting, in regards to the fish oil
conclusion, that these positive results have not been consistently observed
across other large omega-3 trials, Kearney and Rosen offer a reminder
that, "medical literature is replete with exciting secondary end points
that have failed when they were subsequently formally tested as primary end
points in adequately powered randomized trials."
Jane Armitage, from the University of Oxford, also
questions the veracity of some of these secondary conclusions, suggesting
while "they did see fewer heart attacks among those taking the fish
oils," there was also no overall effect seen on all other cardiovascular
events, so this needs to be interpreted cautiously.
In many ways this research seems to be a perfect litmus test in how problematic the reporting of
scientific research can be. The headline on the research from
the Washington Post is, "Fish-oil drugs protect heart health,
two studies say," while the New York Times reports the
exact same research with the headline, "Vitamin D and Fish Oils Are
Ineffective for Preventing Cancer and Heart Disease."
Neither headline is specifically incorrect, however it may
be slightly disingenuous to concentrate on a particular study's secondary
effect when the overall primary finding was negative. The press
release from Brigham and Women's Hospital does nothing to avoid such
cherrypicking, leading with the subtitle "Findings show omega-3 fatty
acids reduced risk of heart attacks, especially among African Americans;
vitamin D reduced cancer deaths over time."
Again, these statements are not technically incorrect, but
they are certainly not in line with the researcher's own published journal
conclusions that clearly state both high-dose vitamin D and omega-3
supplementation do not reduce the incidence of
cancer or major cardiovascular events…..
تعليقات
إرسال تعليق