Wednesday, 12 October 2011

Vitamins and minerals: lost in translation

Vitamin D, vitamin C and the odd probiotic. That's the sum total of my daily vitamin/bacterial supplementation routine as a nearly-middle aged, borderline healthy man. Why just the three supplements? Well my diet is pretty varied, but I do live pretty far North in a place where sunshine is often in short supply particularly in the Winter months hence the vitamin D supplement just in case. I also want to keep supple and probably don't eat as much fruit as I should hence the vitamin C. My gut is my Temple and just to make sure that it stays like a Temple (quiet and serene) I take the probiotic. I take a relatively small dose of each at particular times every day (chronotherapeutics y'know) and whilst a very subjective observation, can often tell when I've 'gone without' for a while. I can hear the whispers already... hasn't he ever heard of the placebo effect? Er, yes.

Like many millions of other people around the world, vitamin (and mineral) supplementation is part of my daily dietary routine. Why did I start taking them? Well... erm, 'the research told me to Sir'. There is for example some evidence that vitamin D deficiency and supplementation could be associated with lots of different conditions and perhaps even more so for certain groups of people. Same for vitamin C. As for the probiotics, well with my borderline obsession with all things gut bacteria on this and my other blogs should be explanation enough. [Note: I'm not in any way, shape or form advocating any vitamin or mineral or probiotic use. If you need more information, speak to your healthcare provider].

Having said all this I am a firm believer in horses for courses and realise that my supplementation routine might not be for everyone, particularly for those sun-kissed, 5+ fruit and vegetable a day, healthy people out there. So it is with some recent publications which have not been easy on some vitamins and other nutraceutical supplements.  This paper by Mursu and colleagues* has received a lot (a lot!) of media coverage with some pretty sensational headlines like 'Are your vitamins killing you?' and 'We've been wasting a ton of money on vitamins and dietary supplements'. Of course when you look at what the study results actually report, you get a little more of a grounded idea of the findings which basically say that based on self-reported supplement use, there was a variably increased risk of mortality in older women (mean age: 60 years+) when supplementing with either a multi-vitamin or a few individual vitamins and minerals including iron, folic acid and copper. Without wishing to belittle what mortality actually means, some the risk was varied; based on the odds ratios detailed and what they actually translate into in terms of hazard. Some of the risk is described as dose-dependent. In other words, take more and your risk might be increased. Another detail of the study on the potentially 'positive' effects of calcium supplementation on reducing mortality for this age proband seems to have been lost in translation.

Now don't get me wrong, I am all for proper testing for safety and efficacy for everything from pharmaceutics to vitamins and minerals to probiotics even to dietary changes; everything, period. If you put it into your body, you should have the comfort of knowing that it does what it says on the box and does it in a safe a manner as possible including any details on other 'drug' interactions or contra-indications. I do however look at the press that this study seems to have received in some quarters and get the feeling that the findings are being somewhat 'beefed-up' from the original results to suit various purposes. Just me perhaps being a little neurotic.

A second study has emerged which again paints a slightly less rosy picture of the value of supplementation. Findings reported by Clarke and colleagues** suggest that some of the proposed health benefits of broccoli, the isothiocyanates, tend to be less pronounced if taken via supplement rather than the real thing as a function of their lacking an enzyme needed to metabolise them properly normally included in the vegetable.

I am actually much happier with the Clarke study; the way it was carried out and reported on (so far). Basically what it says is that Mother Nature knows what she is doing with our vegetables, fruits, etc. and whilst we all think we are skilled in the science of health and the production of 'synthetic health', we perhaps don't yet know as much as she does about the whole being greater than the sum of its parts. I can imagine a few in the medical and dietetics trades as well as the odd pharmacognosist who will see this as evidence for the message about vitamins and minerals being derived from food not supplements as being all important. That being said I, myself, am unaware of anyone who is regularly taking a broccoli supplement for anything.

I have touched upon the themes of 'association' and 'risk' in other posts on this blog. Association or correlation not being the same as causation works both ways in terms of positive and negative suggested connections. Certainly the study by Mursu and colleagues whilst interesting is no different to any other case. I'm not even going to get started on the self-report angle to the study and the potential pitfalls associated with recollection.

I suppose it all boils down to a few messages:
  • treat your vitamins the same way you would your 'regular' medications (dose, side-effects, etc.),
  • if you can get your vitamins and minerals from food, do so,
  • always question any health claim and whether there are indeed published replicated effects (see this recent Nature blogpost),
  • be proactive: research, research, research - don't take anything at face value (particularly sound-bites).
  • the hazards of hazard ratios.
[Just in case you need to know, I have no conflicts of interests when writing this post. I don't have my own line of vitamins or anything, don't have any shares in vitamin companies and I am not knowingly on any council or other body with a vitamin promoting agenda].

* Mursu J. et al. Dietary supplements and mortality rate in older women. Archives of Internal Medicine. October 2011.

** Clarke JD. et al. Comparison of isothiocyanate metabolite levels and histone deacetylase activity in human subjects consuming broccoli sprouts or Broccoli Supplement. Journal of Agricultural & Food Chemistry. September 2011.