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Should We Believe The Latest Vitamin Scare?Happened on 22 April 2008 | ( 0 ) Comments
An updated meta-analysis examining the efficacy of antioxidant supplements in primary or
secondary prevention of mortality was published in The Cochrane Database of Systematic
Reviews 2008, Issue 2, in April 2008. The authors of the meta-analysis conclude that “there is no evidence to support antioxidant supplements for primary or secondary prevention of mortality and that vitamin A, beta-carotene, and vitamin E may in fact increase mortality. Future randomized trials could evaluate the potential effects of vitamin C and selenium for primary and secondary prevention. Such trials should be closely monitored for potential harmful effects.
Antioxidant supplements need to be considered medicinal products and should undergo
sufficient evaluation before marketing.”
These are the same authors that published similar meta-analyses in the Journal of the American Medical Association (JAMA) in February 2007 and in the Lancet in September 2004. Although they have updated their meta-analysis, by handpicking additional studies and correcting a litany of minor mistakes made in previous versions, it is for all intents and purposes not a new study, nor is it truly new information. In fact, it appears to be a systematic attempt by the authors to publish work that supports their own pre-determined conclusions about antioxidants and the way they should be regulated.
The analysis focused on one broad category of study, then evaluated just 67 of the 748 studies that could be included in the review. Therefore, the paper’s conclusions are drawn on less than nine per cent of available evidence. In no way can this review be considered comprehensive. In fact, although the authors claim to be assessing antioxidant supplements for the prevention of mortality, they exclude all 405 studies that reported no deaths whatsoever. The conclusions also go much further than the scope of the evidence and limitations of the individual studies used.
Indeed, the paper’s results focus on all-cause mortality, but the actual causes are not determined
Anti-oxidants ARE important for good health
An extensive body of scientific research has shown that taking antioxidant supplements
consistently over the long-term, can play a role in reducing the risk of chronic disease, therefore an updated meta-analysis published in the Cochrane Database of Systematic Reviews1 should not cause consumers to question the efficacy or safety of antioxidant supplements.
Patrick Holford one of the UK’s leading nutritionists comments on the review, which claims
potential harm from taking antioxidant supplements:
“It’s a stitch up. If you look objectively at all the studies reviewed, which were chosen strictly
for reducing mortality, and not for the many other benefits reported in other studies, Bjekalovic et al conclude ‘Beta-carotene, vitamin A and vitamin C, used singly or in combination with other antioxidants had no significant effect (on mortality)’, although a number of vitamin C studies did report reduced mortality. . . and that ‘selenium used singly or in combination with other antioxidants significantly decreased mortality’”.
The only way this review could produce the negative results was by finding reasons to exclude most of the positive studies, including all the positive ones on selenium. Their basis for exclusion in a previous meta-analysis published in JAMA (Journal of the American Medical Association) has been heavily criticized in mainstream medical journals.
One of the world’s leading experts in this field, Dr Balz Frei, said “This is a flawed analysis of flawed data, and it does little to help us understand the real health effects of antioxidants,
whether beneficial or otherwise.”
Patrick Holford says, “Anti-oxidants are not meant to be magic bullets and should not be
expected to undo a lifetime of unhealthy habits. But when used properly, in combination with eating a healthy diet full of fruit and vegetables, getting plenty of exercise and not smoking, antioxidant supplements can play an important role in maintaining and promoting overall health.”
Kevin Leivers pharmacist consultant for Natures Sunshine says, “The idea that taking anti
oxidants from fruit and vegetables could be harmful to our health does not make common sense and looking at this research, it does not stand up to rigorous scientific scrutiny either. I take, and will continue to take the antioxidant drink Zambroza and also eat a diet high in fruit and vegetables.”
"Healthy consumers can still feel confident that they can safely take their antioxidant
supplements," said Dr Michele Sadler on behalf of the Health Food Manufacturers’ Association.
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