A major study published last week found that taking a standard multivitamin pill lowered the risk of developing cancer. Published in the Journal of the American Medical Association, this large-scale, randomized, double-blind, placebo-controlled trial of 14,641 male physicians in the US aged 50 years or older, found that taking a daily multivitamin supplement reduced the risk of developing cancer. Inevitably, this has been accompanied by triumphant headlines, lauding the benefits of multivitamins (and you can just imagine the supplement industry rubbing its hands in glee). So, it begs the big question, should we all be popping a daily multivitamin to protect against cancer?
The first thing to point out is that the size of the benefit in this study was modest, amounting to an 8% reduced risk in cancer incidence in those taking the daily multivitamin supplement (and we should note that there was actually no significant difference in the risk of cancer mortality). But still, 8% is 8%, and in the war against cancer, most of us would welcome nudging the odds in our favour.
But don't get too swept away with the idea that multivitamins are some sort of panacea. Relying on multivitamins to quell our cancer risk is misguided for three reasons:
1. Multivitamins are a poor relation to real food. Unlike their synthetic counterparts, real food contains a mind-boggling diversity of not just vitamins and minerals, but hundreds, indeed thousands, of bio-active plant compounds, known as phytonutrients. Prize candidates include lycopene (cooked/processed tomatoes), catechins (green tea), glucosinolates (cruciferous vegetables such as broccoli), quercetin (onions), sulphur compounds (onions and garlic), anthocyanins (berries), luteolin (celery), chlorogenic acid (coffee), flavanols (cocoa), lupeol (mango), resistant starch (legumes), isoflavones (soya), and the list could go on and on.... In essence, what we find is a complexity and synergism of bio-active nutrients that mere multivitamin pills can't come close to replicating.
2. Multivitamins are an unintelligent scatter gun approach to supplementing nutrients, conceived on the premise of providing 'a bit of everything'. The trouble with this approach is that whilst we get some nutrients we really do need, we also get some we don't. Surely, a more sophisticated strategy is to just supplement with the nutrients that are genuinely missing from our diet, at just the right dose? We strongly argue the case for a more informed and intelligent use of nutritional supplements in The Health Delusion, highlighting in particular the two nutrients that Brits simply don't get enough of: vitamin D (especially in the winter) and selenium. Your multivitamin will contain these nutrients, but the chances of them being present in optimal amounts (especially vitamin D) is slim, and a disappointment when we consider that both of these nutrients are likely to be powerful allies for cancer protection (you can find my recommendations for winter supplementation of vitamin D and selenium here).
3. Being lulled into the belief that multivitamins are the answer may divert attention from the really important dietary factors more conclusively proven to lower cancer risk. For that, look no further than the profoundly helpful report on diet and cancer compiled jointly by the World Cancer Research Fund and the American Institute for Cancer Research. Representing the scientific consensus from a small army of leading experts, it synthesizes research from across the globe into a set of clear recommendations. Examples of these recommendations include maintaining a healthy weight throughout life (perhaps one of the most important ways to protect against cancer), being physically active as part of everyday life, eating mostly foods of plant origin (such as fruits, vegetables, minimally processed cereals, pulses), limiting intake of red meat and avoiding processed meat, and limiting alcoholic drinks. For anyone motivated to reduce their cancer risk through diet (and physical activity), this is the stuff we should really be taking notice of.
The message here is not to throw away your daily multivitamin. It goes almost without saying that dietary and lifestyle changes are notoriously difficult to make, whilst taking a pill is easy. So if you do take one, stick with a relatively modest dose product (as was used in this study, which incidentally was 'Centrum Silver'), and avoid unnecessarily high doses, especially of antioxidants (such as vitamins A, C, E and beta carotene), which as we spell out in The Health Delusion are likely to do more harm than good. But for those serious about slashing their cancer risk, I'd recommend you focus your efforts elsewhere first, before rushing for the pill pot.
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