Study links antioxidant supplements to increased mortality

A meta-analysis of 68 randomised trials with antioxidant supplements published in JAMA has reported that vitamins A and E, and beta-carotene may increase mortality risk by up to 16 per cent, but vitamin C did not have an effect on mortality and the antioxidant mineral selenium was associated with a nine per cent decrease in all-cause mortality.

Many of the studies included only subjects already classified as suffering from certain diseases. Indeed, only two of the studies classified as "low bias" were carried out in the 'general population'.

The study has been slammed by the US-based Council for Responsible Nutrition, who said the researchers "misuse[d] meta-analysis methods to create generalized conclusions that may inappropriately confuse and alarm consumers who can benefit from supplementing with antioxidants."

Moreover, Andrew Shao, Ph.D., CRN's vice president, scientific and regulatory affairs said that the combined studies were far too diverse and different in terms of dosage, duration, study population and nutrients tested that the results of the analysis were "compromised".

Additionally, Dr. Shao noted that most of the trials included in the meta-analysis tested for secondary prevention, looking at how a nutrient works in diseased populations, instead of primary prevention studies in healthy populations.

"Combining secondary prevention and primary prevention trials and then making conclusions for the entire population is an unsound scientific approach," said Shao. "Additionally, many of the trials had limitations, including the expectation that a simple antioxidant vitamin could be expected to overturn serious illness, such as cancer or heart disease. These trials likely statistically skewed the results."

Daniel Fabricant, vice president of scientific affairs for Natural Products Association (NPA), another US-based trade association, supported this view.

"Despite the authors' contention, this analysis is assessing mortality of at-risk and diseased populations - versus a healthy population - in prevention trials. The risk of mortality must be attributed to the appropriate population studied, those with an existing health condition, which it isn't in this case. Instead, those findings are generalized to a healthy general population, which is wrong on many levels," said Fabricant.

"But what's most troubling is that people who are safely and beneficially taking vitamins might stop, which may actually put their health at greater risk."

Fabricant also stated that if a true mortality risk had been apparent in any of these clinical studies using antioxidants, the study would have been halted, but none were.

"Nearly 160 million people in North America and Europe use the attributed supplements. If antioxidants were a significant public health risk, as the authors speculate, it would have become clearly apparent by now," he said. "This is obviously not the case: the negative effect they refer to has not been seen in the population."

Bonnie - at the risk of sounding like a broken record, when are they going to stop with the meta-analyses! Every one of them (i.e. vitamin E meta analysis published in 2005) have been found, after the fact, to be misinterpreted, inaccurate, and discounted. Even experts from outside the industry, such as Harvard's Meir Stampfer, have already said that meta analysis is like comparing apples and oranges. A professor of nutrition and epidemiology at the Harvard School of Public Health who was not connected to the meta-analysis, Stampfer told the Associated Press that the studies reviewed were too different to be able to pool them together."This study does not advance our understanding, and could easily lead to misinterpretation of the data," Stampfer said. The more they keep analyzing nutrients-for-disease model, the further they get away from the reason supplements are prescribed, for prevention. Must I reiterate that the allopathic medical community does not and may never adhere to a preventative mindset.