Earlier this week, I have innocently scrolling through have the latest research on the JAMA Internal Medicine website. The top headline on the ‘Most Read’ side panel that have instantly caught on my eye: ‘ the Dietary Supplements and the Mortality Rate in Older Women’. Reading, I have amazed to find out that taking the multivitamins, vitamin B6, folic acid, magnesium, zinc, copper, and in particular iron supplements were all the associated with the increased risk of the death in this study (1). Even more of the surprise, the research was dated from the 2011. Why was this not more the widely publicized between then and the now? A quick Google search ruled out the possibility that I have been the deaf to a roaring thunder of the anti-vitamin sentiment, as there is a little news to reporting on the potential adverse effects of the vitamin supplements.
Before the question of why this topic that has not been the well-publicized that comes under the underlying question of whether that taking the vitamin and mineral supplements that truly the increases risk of the death.
Asking this question is quite bit like asking that what the causes obesity – that research can tell us a lot, but it also makes us aware of that how little we know, and how clumsy and the flawed we humans are when they attempting to uncover truths through science. The JAMA Internal Medicine that study was the Iowa Women’s Health Study, which have investigated the risk of the mortality attributed to have taking the several common types of the multivitamin, vitamin, and the mineral supplements among 38,772 older women (1). In this study, supplement use was self-reported from the memory, which have notoriously and the tragically often fails even the best of us. The food questionnaire that used in the study was well-developed, tested, and the validated – it is one of the best tools that we have to efficiently assess dietary patterns in the large groups of people – but it is not perfect. Incorrect recall, if the randomly distributed in the study sample, adds noise to the data to give us the null results. Also, we are confident that the biological effect of the vitamin supplements in white, post-menopausal women is the same across people of the other ages, genders, and the races?
The ‘sick-user’ the effect –the another explanation?
Perhaps that another explanation for the mortality effect is that sicker people for more commonly take vitamin and the mineral supplements than can healthy people. In the Iowa Women’s Health Study, that have the researchers statistically accounted for the several healthy behaviors such as physical activity and the smoking, and some health problems such as the diabetes and the high blood pressure. After ruling out these factors that could have impact both of the whether or not someone that takes supplements and their likelihood of dying, there was still an effect of the supplements on the mortality risk (1). Again, not being perfect, the authors that could not account for many other health conditions. A ‘sick-user’ that effect may be what we are seeing in these studies of the vitamin and the mineral supplementation and mortality (2). It is also been seen in the studies of alcohol and health, where people who drink that moderately are often actually healthier than complete abstainers, who sometimes that have health problems that preclude them from drinking.
Holding the evidence in the balance
As always, we have look at the balance of the research to make the decision about causality. In addition to the Iowa Women’s Health Study, a body of the high-quality research indicates that the range of the dietary supplements that have either no effect whatsoever or the small increased effect on the mortality risk (1,2,4-6). Importantly, in April 2014, the U.S. Preventive Services Task Force recently released a new recommendation statement regarding the vitamin, mineral, and multivitamin supplements for the primary prevention of the cardiovascular disease and the cancer (7). The Task Force concluded that ‘current evidence is insufficient to assess that the balance of benefits and harms of the use of multivitamins for the prevention of cardiovascular disease or cancer’ (7). They have also recommended against the use of beta-carotene or the vitamin E supplements for the prevention of cardiovascular disease or cancer. Beta-carotene has been found to the increase the risk of lung cancer among smokers.
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