Human Limits

There are a large number of vitamins and other supplements that are purported to improve metabolic health, cardiovascular risk and perhaps have anti-aging effects.  The idea is that is that these products do things like lower blood pressure, improve blood lipids, and reduce the risk of diabetes.   The consumer market for these products is huge with about 27 billion dollars spent in the U.S. during 2009.

 

Do They Work?

There are a couple of ways to answer the do they work question.  The first way is to survey the population and see what the health of users and non-users looks like.   When this was done in about 300 multiple supplement compared to about 600 non-users, the supplement users came out ahead for many variables associated with better long term health.

 

Dietary supplements consumed on a daily basis by more than 50% of Multiple Supplement  users included a multivitamin/mineral, B-complex, vitamin C, carotenoids, vitamin E, calcium with vitamin D, omega-3 fatty acids, flavonoids, lecithin, alfalfa, coenzyme Q10 with resveratrol, glucosamine, and a herbal immune supplement. The majority of women also consumed gamma linolenic acid and a probiotic supplement, whereas men also consumed zinc, garlic, saw palmetto, and a soy protein supplement……After adjustment for age, gender, income, education and body mass index, greater degree of supplement use was associated with more favorable concentrations of serum homocysteine, C-reactive protein, high-density lipoprotein cholesterol, and triglycerides, as well as lower risk of prevalent elevated blood pressure and diabetes.

 

Pretty convincing, except who knows what other health behaviors the supplement users were engaging in.  For example, they might have been exercising more or eating a generally healthier diet than non-users.

 

So, what happens to the blood pressure, lipids and glucose levels to matched groups of people given multiple supplements prospectively?  Do they make a difference?  When about 60 generally healthy middle aged men and women were randomized to receiving either a standard multivitamin or a multivitamin and supplement cocktail containing resveratrol, quercetin, carnitine, alpha-lipoic acid, curcumin, pomegranate extract, fish oil, cinnamon bark, green/white/black tea complex and sesamin:

 

“The main outcome measures were arterial stiffness, endothelial function, biomarkers of inflammation and oxidative stress, and cardiometabolic risk factors. Twenty-four weeks of daily supplementation with 10 dietary supplements did not affect arterial stiffness or endothelial function in nonobese individuals. These compounds also did not alter body fat measured by DEXA, blood pressure, plasma lipids, glucose, insulin, IGF-1, and markers of inflammation and oxidative stress. In summary, supplementation with a combination of popular dietary supplements has no cardiovascular or metabolic effects in non-obese relatively healthy individuals.”

 

What About Vitamins?

The data on vitamins is generally worse.  At least one analysis that has evaluated all of the studies on vitamin E supplementation suggests that relatively high doses might increase all-cause mortality.  Others have concluded that there is likely no effect.  There might also be issues with vitamin A.  When the effects of vitamin C and vitamin E on longevity and lifespan are evaluated in “model organisms” like fruit flies and rodents, the data is all over the place.  Here is a summary for the vitamin E studies:

 

Twenty-four studies were included in the final analysis. While some studies suggest an increase in lifespan due to vitamin E, other studies did not observe any vitamin E-mediated changes in lifespan in model organisms. Furthermore there are several studies reporting a decrease in lifespan in response to vitamin E supplementation. Different outcomes between studies may be partly related to species-specific differences, differences in vitamin E concentrations and the vitamin E congeners administered. The findings of our literature review suggest that there is no consistent beneficial effect of vitamin E on lifespan in model organisms which is consistent with reports in human intervention studies.

 

To Take or Not To Take?

Based on the summaries above, it is hard to make a convincing argument that anyone without evidences of a primary vitamin deficiency should be taking vitamins.  This is especially true if your diet is high in fruits, veggies, “good fat” and you are physically active.  Pretty much everything vitamins and supplements are supposed to fix can be optimized with a reasonable diet and plenty of exercise.

 

 

This entry was posted on Tuesday, February 18th, 2014 at 5:19 am and is filed under Current Events, Research and Health. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.