Antioxidants have long been recognised for their protective properties against damaging free radicals and the health problems they cause. Consequently, a recently published controversial study by the Copenhagen University Hospital examining the effect of antioxidants on prevention of mortality has been the focus of much attention in the media, making the BBC Breakfast News and the front page of the Daily Telegraph. The authors of the study concluded 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”

However, when examining the Copenhagen study, a number of key points come to light. The study itself is a meta-analysis, which means that the results of several studies in related fields are combined using statistics to draw an overall conclusion. By their very nature, meta-analyses require a selection process to decide which studies to include in their review.

This meta-analysis only evaluated what are called randomised controlled trials, where patients are put in 2 monitored groups and given either a tablet or a dummy-pill. The study failed to include any of the vast body of long term observational studies that also exist, so the evidence base is very limited.

In addition, the researchers identified 748 studies that met their criteria but they excluded 681 of them, so their results are based on less than nine percent of the available evidence. What’s more they specifically excluded any trials in which no deaths were reported (405 articles). This raises the question, how one can properly evaluate whether a substance can prevent mortality when studies that demonstrate no harm are automatically excluded?

The authors also chose not to eliminate deaths due to other circumstances such as accidents, medical conditions and suicides. They chose instead to assume that all the deaths that occurred in any of the studies were attributable to the antioxidant supplements. This is particularly ironic since many of the studies involved groups of people with a variety of health issues, not just those who were healthy. In fact, if a true mortality risk were to have become apparent in any of the original studies, they would have been halted. Interestingly, none were.

In addition, the studies they did select covered a vast range of different nutrients, doses, populations, and durations. This makes it very difficult to effectively combine the evidence and draw proper conclusions. As the saying goes, it’s like comparing apples to oranges.

Some of the studies also included extremely high doses of supplements, far in excess of the Tolerable Upper Limit specified by the Institute of Medicine and many used synthetic forms of nutrients. This may have significantly skewed the overall results. Higher Nature as a company make a concerted effort to use natural or True Food forms of nutrients, as they would be found in foods. We also make sure the levels of all our nutrients are safe by never exceeding the levels set out by the Food Standards Agency and consulting with our 2 medical doctors whenever we make a new product.

Overall, it would seem that the negative results found by this review occurred because all the positive studies using safe levels of supplements were excluded. Consequently, the basis for exclusion has been heavily criticized. Dr Balz Frei, Director of the Linus Pauling Institute, one of the world’s leading institutes that studies the possible health value of vitamins and micronutrients, has 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.”

The authors appear to be using their study as a campaign for greater regulation of supplements, yet their study makes no references to any of the regulatory procedures already in place. New European legislation means that all the ingredients of food supplements are in the process of being stringently safety assessed and maximum and minimum levels set. In the meantime, all responsible manufacturers adhere to a set of dietary reference values based on a large body of safety research by the Institute of Medicine, a branch of the US National Academy of Sciences, which provides evidence-based advice on health issues.

As Dr Alexander Schauss, Senior Director of Natural and Medicinal Products Research points out: “There exists a firm scientific foundation based on thousands of studies…on the role of oxidative stress in the development of chronic and degenerative diseases.” Whilst antioxidant supplements cannot be expected to undo a lifetime of unhealthy living, in combination with good lifestyle choices and a healthy diet they can play an important role in promoting overall health and wellbeing.

© Higher Nature 16.04.2008