Image 1: "Please Dr. Andro tell me I can keep taking my essential multivitamin! I am just too busy to eat healthy..." |
Dietary Supplements and Mortality Rate in Older Women
Image 2: Is this you? No? Maybe she is "The Average American", then? No? Well, but the study says "vitamins are bad for YOU" and she could be one of the subjects (img. medscape.org) |
Now, if you are still with me at this point, I guess that you either are a post-menopausal white woman, or - and I suppose that this will be the case for the majority of you - you have been agitated by the heated debate on the net (and even regular mass-media) in the last couple of days and want someone to tell you that you did not reduce your life-expectancy by -15% by religiously taking your "essential" *rofl* multi-vitamin, everyday. We will see, whether I can be this person (in case it turns out I am not, I have seen more than enough "gurus" you will tell you exactly that, if you promise to buy their "all natural" or "superior source" product in the future).
The Iowa Women's Health Study - Mrs "not so average" American
So, let's see. What we have here is an offshoot of the Iowa Women's Health Study (IWHS), which is one of those highly over-estimate surveys, the media loves, because they boast of ten-thousands of "participants". In the case of the IWHS, "41836 women aged 55 to 69 years"... well, at least that were the women the scientists send their little questionnaires to back in 1986. Interestingly, this is also where the first bias (i.e. a deviation from "objectivity") came into play:
Respondents were slightly younger, had lower body mass index (calculated as weight in kilograms divided by height in meters squared), and were more likely to live in rural areas compared with nonrespondents.So instead of the average American "older woman", the scientists suddenly had the "slightly younger" not just as obese, better off American older women, as their study object. Moreover, the number of participants dropped to 38772 women or, in other words, the scientists "lost" 7.3% of their study population even before the study actually began. Now, of those, the Mursu et al. selected 29230, who were the "elite" which responded to both the initial 1986 and the 2nd 1997 follow-up questionnaire.
Failure 1: Not representative of "The Average American"
"Ladies, give me as little information about your supplements as possible, please!"
The latter, i.e. the questionnaire, assessed the use of 13 supplements:
- multi-vitamins;
- vitamins A, beta-carotene, B6, folic acid, B complex, C, D, and E;
- iron, calcium, copper, magnesium, selenium, and zinc
Failure 2: Ignorance towards the fact that
not all vitamins / minerals with the same label are created equal
not all vitamins / minerals with the same label are created equal
And as if this had not been enough, the scientists did not even care if the ladies popped 1 or 23 of their beta carotene (I hope you do not still believe you can take endless amounts of that orange poison), magnesium, folic acid and B-complex pills.
Failure 3: Careless ignorance towards dosages
Raw foods are dangerous and so is raw data
Hence, the scientists got a set of data that was full of holes from a group of women who are by no means representative of "The Average American" (let alone every human being) - what did they do next? Well, obviously "raw data" is as dangerous as raw meat (or even raw milk), that is why the next step for every good scientists is data processing. In that Mursu et al. were particularly skilful as far as not revealing what they actually did was concerned:
In the minimally adjusted model, we adjusted the association for age and energy intake; in multivariable adjusted model, version 1, we additionally adjusted for educational level, place of residence, diabetes mellitus, high blood pressure, body mass index, waist to hip ratio, hormone replacement therapy, physical activity, and smoking status. For multivariable adjusted model, version 2, we added intake of alcohol, saturated fatty acids, whole grain products, fruits, and vegetables.Even, or I should say, especially for a physicist, who is a 75% mathematician, the idea that by some sort of mathematical magic you could reliable subtract out all those influence, so that you get the "real picture" of what is going on, with an average human being is so hilarious that I avoid any further comment. Everything that goes beyond the "minimal adjustment" is so full of speculative hypothesis and mainstream paradigms (like "Whole grains are good for you! The more, the better!") that I will simply ignore this data... unfortunately these results of "3+3 = 666" mathematical manipulation were what the scientists (in their press releases) highlighted as their main results and what was accordingly taken up by the laymen (initially I wanted to write idiots, but that would be unfair, because laymen they are) in the editorial offices of the mass media.
Failure 4: Over-"analysis" of the data
Let's get to the raw truth
This would not be the SuppVersity, if I did not have something to offer that goes beyond the angry rants and criticism (see above) you probably have read elsewhere, anyways. So, I went through the pains of compiling and comparing the "real", i.e. the N=X data and not the calculated hazard ratios for you.
Figure 1: Raw data and minimally adjusted (age and caloric intake) data on the effect of taking vitamin A, beta carotene, vitamin C, vitamin D, vitamin E, and finally the multivitamins on overall mortality (data calculated based on Mursu. 2011) |
- the 1.04 as for vitamin A (minimally adjusted) in 2004-08 indicates a +4% higher risk and 0.80,
- the 0.80 for vitamin E (raw data) in 2004-08 indicates a -20% decrease in mortality risk
Figure 2: Raw data and minimally adjusted (age and caloric intake) data on the effect of taking vitamin B6, folic acid, B-complex, calcium, and magnesium on overall mortality (data calculated based on Mursu. 2011) |
Figure 2: Raw data and minimally adjusted (age and caloric intake) data on the effect of taking iron, copper, zinc, and selenium on overall mortality (data calculated based on Mursu. 2011) |