The bulk of the evidence shows that popping of vitamin and mineral pills is generally safe and has the potential to benefit the body. However, despite this, stories do occasionally surface which suggest that nutritional supplements are, at best, useless, and at worst, may actually increase our susceptibility to illness. My experience is that the studies behind such stories often do not stand up well to scientific scrutiny. Some have suggested that the press has a habit of ignoring critical detail in its rush to make good copy and boost sales. However, my reckoning is that cries for more responsible journalism should be focused less on the lay press, and more on the medical journals that publish scientifically suspect studies in the first place.
These issues were recently at the forefront of my mind as a result of being asked to give a talk on scare stories about supplements, and the forces behind them. Two days before I was due to deliver my lecture, the British Medical Journal (BMJ) published an edition sporting the headline: Vitamin and minerals for elderly people – No good evidence that they reduce infections�. Given the topic of my impending address, I couldn’t resist reading the relevant study in the BMJ with a critical eye.
The study in question pooled together the results of several studies which had assessed the effect of nutrient supplementation on infections in the elderly. Three specific effects were measured: the total number of ill days caused by infection (outcome 1), the number of individuals who suffered at least one infection during the course of the study (outcome 2), and the average number of infections suffered by study participants (outcome 3). The study found that, compared to placebo (inactive medication), nutrient supplementation did not bring statistically significant reductions in outcomes 2 or 3. As a result, the study authors concluded that the evidence for the use of supplements in the elderly was ‘weak’.
While these findings are disappointing, one might argue it is perhaps more relevant to consider what effect, if any, nutritional supplementation has on outcome 1. This BMJ study showed that on average, the taking of a daily multivitamin and mineral pill reduced the number of ill days by more than 17 per year – a result that was highly statistically significant. In light of this, the slant given to the results of this study by its authors and BMJ seems somewhat curious.
What is even more puzzling, perhaps, is that very shortly after this study was published, the deputy editor of the BMJ posted an electronic response questioning the validity of two of the individual studies within it that found benefit. It does seem a little odd that this issue did not come to light prior to publication. And one wonders what all of this says about the much-lauded peer-review process; where appointed academics are given the responsibility of ensuring poorly conducted or suspect studies do not make it to publication? While medical journals are generally seen to uphold the values of intellectual and scientific rigour, it seems they are no different from newspapers regarding their capacity to churn out bad press.