CRN castigates Lancet for incendiary reporting
the article published in last week's Lancet - which suggested that
dietary supplements may be doing more harm than good, and accused
the journal of "creating publicity over practicing journalistic
integrity".
Scientists from the University of Niss, Serbia and Montenegro, and the Cochrane Hepato-Biliary Group carried out a review of previously published trials, where antioxidant supplements had been used for the prevention of gastrointestinal cancers.
The researchers looked at 14 randomised trials - totalling over 170,000 participants - before concluding that supplementation with b-carotene, vitamins A, C, E, and selenium (alone or in combination) compared with placebo on oesophageal, gastric, colorectal, pancreatic and liver cancer incidences provided "no protective effect".
They then went a step further and concluded there was "a small but statistically significant increase of 6 per cent relative risk in mortality among people taking antioxidants compared with placebo". And added that two combinations of supplements, namely b-carotene and vitamin A and E, were associated with an even higher relative mortality risk of 30 per cent for b-carotene and vitamin A and 10 per cent for b-carotene and vitamin E.
"We could not find evidence that antioxidant supplements can prevent gastrointestinal cancers; on the contrary, they seem to increase overall mortality," said lead researcher Dr Goran Bjelakovic.
The CRN expressed its unhappiness with many aspects of the research, but saved its real annoyance for the way in which the Lancet had reported the findings.
"It's not news to say that we don't know for sure what might prevent cancer," said Annette Dickinson, president of the CRN, questioning the rationale of using "only three studies that focused on healthy people".
"While studies can successfully draw upon unhealthy populations to find solutions for healthy populations, antioxidant supplements alone should not be expected to reverse the negative effects created by a lifetime of smoking or poor dietary habits," she said.
Her colleague - the CRN's vice president, scientific and international affairs, John Hathcock - added that he saw little value in comparing different supplements in the same meta-analysis.
"Comparing different supplements in the same meta-analysis results in violating a primary rule of meta-analysis - combining only similar studies - and discounts the valuable information one would otherwise learn about the individual supplements," said Hathcock.
"Averaging out the effect of beta-carotene and selenium in the same meta-analysis is like saying if you have a husband who is morbidly fat with a wife who is morbidly thin, you've got a couple with an ideal weight," he said.
However, the trade body was most aggravated by the way in which the Lancet had decided to present the research by highlighting the following quote by David Forman from the University of Leeds, UK and Douglas Altman from Cancer Research UK: "If their findings are correct, 9000 in every million users of such supplements will die prematurely as a result. The prospect that vitamin pills may not only do no good but also kill their consumers is a scary speculation given the vast quantities that are used in certain communities". The CRN believed instead the journal should have focused on the fact this research is still in its preliminary phase.
"Lancet's handling of this article makes it frighteningly clear that we have moved into an age where getting headlines takes precedence over a scientific journal's responsibility to report without bias," said Dickinson.
Indeed, Forman had told NutraIngredients.com last week that although he felt comfortable with the conclusion there was no proof that vitamin supplements had protective effects against gastrointestinal cancer, he felt the authors of the study had more confidence in the findings that supplementation could be responsible for premature deaths than he did.
"This is somewhat preliminary and there are a number of statistical problems with the way the researchers looked at the data," he said. He noted that a particular problem was the inclusion of one study, which had used an "abnormal" group of patients, including people that were unhealthy and smoked.
"Part of the problem is also that the researchers looked at all available studies dealing with gastro-intestinal cancer and supplementation, but they now need to do another study taking into consideration all papers on mortality and supplementation," he added.
The group is now carrying out such research, but - depending on the results - it could have been beneficial to the supplement industry if this study had been concluded before such potentially damaging research was published.
