Friday, December 30, 2011

A "Question of Faith": Do Multivitamins, Antioxidants and Mineralsupplements Improve Your Quality of Life?

Image 1: Do you believe that you could solve this profound imbalance by randomly adding more people to both sides of the seesaw? No? Well, why are you taking a high-dose multivitamin then?
As the name of this website already implies, I am an outspoken believer in the usefulness of "supplements" (as in "to supplement" = to add to something, where it makes sense). There is however a particular group of "supplements", which is a real thorn in my side... Yes, I am talking about those one-size-fits-it-all-multivitamin-multimineral-multi-whatever products with "high quality ingredients" the ratios of which are based on either the "recommended dietary allowances" of the omniscient USDA (actually a way better name would be "random dietary allowances") or the even more idiotic maxime that "if some is good, then more is probably even better". These days every major supplement company has at least one of these formulas in their line-up and obvoiusly they all will claim that only their product will provide you "with all the vital nutrients you need".

Wtf!? How do those guys know which nutrients I need? 

Even if those formulas were perfectly balanced - which they certainly are not, because we simply don't know what the "perfect balance" is, yet - the chances that anyone of you, my educated, well-nourished whole-food eating readers, has a full-blown, all across the board nutrient deficiency that would be fixed by any of those products are probably one in a million. What is much more likely, though is that you have a small or (oftentimes due to "healthy supplements") profound nutrient imbalance.

Let's say you are an aspiring male fitness athlete and have been taking your ZMA religiously for years. At the same time you have heard that copper is not only bad for you, but that "we all" would get way too much copper in our diet, anyways. So you have been avoiding copper like a plague and ingesting 30mg of zinc from your ZMA everyday... now chances are that you have already set off the natural (and optimal) ratio of copper to zinc in your body. Let's say the optimal ratio was 1:12 (copper to zinc, and again - we do not even know what the optimal ratio would be). With your high zinc and low copper intake you are now at 1:20, i.e. 60% off! Now the nice guy from your local GNC convinces you that it would be prudent to add the brand new "Male Super-Power Vitamin" to you supplement regimen if you wanted to live a long and healthy life. Chances are that the guy who designed that product will also have heard that zinc is good for men and that we all get way too much copper (and even if he knew better, he will be aware that his formula won't sell if it does not follow conventional stupidity... ah, I mean wisdom). So, the product will have 200mcg of copper and 30mg of highly bioavailable zinc - I mean it's a "high quality product"! What is going to happen now? What? Right! The well-formulated product will exasperate you existing imbalance... Your multi does not do that? How come you think so?

"Ever since I take my multi, I have not become sick and feel way better!"

Right, you feel better... and you are not alone! In fact many of the 8112 participants in a well-controlled randomized, double-blind, placebo-controlled, primary human intervention trial which was conducted by a group of scientists from Paris (Briancon. 2011), also felt that the capsule with 120 mg vitamin C, 30 mg vitamin E, 6 mg beta-carotene, 100 µg selenium and 20mg zinc, they had been taking for 76 months(!) improved their overall well-being.
Warning! I suggest you don't continue reading the following paragraphs if you do feel that your vitamin product works and do not want to take the risk that it will stop working as soon as you have finished reading this blogpost ;-)
What is pretty strange, though, is that this effect did not depend on whether the subjects actually received the anti-oxidant + mineral combination, or not. Rather, the main determinant of the the results of the health-related quality of life (HRQoL) questionnaire in this sample of healthy French adults was whether the subjects, who, as it is right and proper for a "placebo-controlled" trial, obviously did not know whether they were ingesting a capsule with the active ingredients or the placebo (it had been established in a previous study that the two capsules were indistinguishable; cf. Hercberg. 1998), believed that they were in the active arm of the study (cf. figure 1, believers vs. non-believers):
Figure 1: Perceived effect on global health (VAS) in subjects who had "no idea" whether they received the active or the placebo treatment and subjects who thought they received the active ("believers") or placebo ("non-believers") treatment (data adapted from Briancon. 2011)
What is also interesting, is that women were slightly more susceptible to placebo effect than men (not to the nocebo effect though), although this difference did not reach statistical significance.

Multivitamins are like religion: Believe in it and it works!

A pros pos statistical significance, as far as the "real" markers of health and disease are concerned, the "key message" (I use the words of the scientists ;-) of the SU.VI.MAX was that "long-term supplementation with antioxidant vitamins and minerals has no effect on quality of life" - in other words, although there were not measurable improvements, the study did not provide further evidence for the hypothesis that long term supplementation with anti-oxidant supplements, selenium and vitamin E in particular, had any negative effect on objectively measurable health markers (if you want to read more about the flawed analysis of and biased media reports on the data from the SELECT trial, read my previous blogpost on this issue).
Image 2: Add a body made of animal products to this guy and you have all the nutrients you need ;-)
It should be mentioned here that in a previous analysis of other data from the same cohort, the scientists had found a small, but statistically significant decrease in cancer and all-cause mortality among the male study participants of the active arm of the SU.VI.MAX trial (Hercberg. 2004). So, while the quality of life did not improve, the miserable life of some of the male subjects was at least extended by a few years ;-) All sarcastic jokes aside, even the scientists realize that in the presence of conflicting evidence, the "major implication for public health of the present findings is that a lifelong diet rich enough in vitamins and min-erals may be preferable to supplementation that is likely not to be efficacious and has the potential to be harmful." - sound advice!
Those of you for whom this is not the first visit, here at the SuppVersity, will be aware, that, as a trained scientist, I don't content myself with the conclusions my "colleagues" (from another branch of science) draw. Therefore, I dug a little deeper into the actual data that comes with the study and - alas! - I was able to find a statistically significant (p<0.014) increase in the reported "vitality" among the women who actually received the vitamin + mineral supplement (cf. figure 2):
Figure 2: Real (difference between treatment and placebo) and perceived (difference between "believers" and "non-believers") of antioxidant + mineral supplement (data calculated based on  Briancon. 2011)
What is strange though, is that of all statistically significant differences between women who believed they received the supplement and those who did not, just this one is the least distinct. Moreover, in all the other variables, where there was a statistically significant difference between believers and non-believers, the "real" data (meaning the comparison of subjects who actually received the treatment vs. the placebo group) could not confirm the positive self-assessment of the believers. Among the male subjects, there was even a trend toward reduced quality of life measures in the real data, where the "believers" thought that it was the "supplement" they were taking that soothed their bodily pain, improved their general health or overall physical performance (physical summary scale).

So what? Am I wasting my money?

These additional observations do yet not falsify any of the three main conclusions, Serge Briacon and his five colleagues from Nancy University, the Metz University, the University Paris Descartes, the University hospital of Nancy and the French Department of Public Health draw based on their interpretation of the data:
  1. [t]here is no proof that supplementation with these vitamins and minerals is beneficial in participants whose dietary intakes are already sufficient
  2. [t]he perception that supplementation improves general well-being is not supported by this trial.
  3. [a] reverse causal pathway may even be advocated (healthier participants may have been more likely to believe they were in the supplement group).
What this means for you is that if your multivitamin "works", chances are that you are doing something right as far as your general lifestyle, your diet and your exercise regimen are concerned. If despite taking your multi religiously, you still feel miserable, you better take a closer look at what your real problems are instead of switching from one band-aid-fits-it-all "solution" to the next one.