Tuesday, January 31, 2012

Does the Usefulness of Vitamin E Supplementation Depend on Your Activity Level? Profound Decreases in Baseline and Peak Exercise Induced DNA Damage Would Suggest So

If you are an athlete, let's say a competitive rower who trains 3+h per day, it appears as if 400IU of vitamin E would be nothing, but beneficial. If you are a couch potato, though, even that may hamper the small hormetic response you get from taking the stairs once a week ;-)
I don't know if you do remember, but it is actually not all too long ago that vitamin E was what vitamin D is known: The highly celebrated non-pharmacological savior of the ailing human race. Cancer? Heart disease? Diabetes? Alpha-tocopherol, which proved to be the most potent anti-oxidant in the tocopherol family, would solve all your problems and with its ability to "scavenge" the bad "free radicals" (sounds like a story from the Brother's Grimm, doesn't it?) it would also prolong your life expectancy. After all, those mischievous reactive oxygen species were the primary drivers of the aging process... well, today we know better. Supplemental vitamin E alone does neither prevent nor cure any of the diseases of the civilization. And the "free radical theory of aging" has come under fire, as of late (cf. previous blog posts on hormesis).

Vitamin E - fallen angel or an angelic demon!?

After being disregarded by the disappointed lay-press for years, vitamin E has gotten quite a bad rep, as of late. "Journalists" claimed that scientists had found that instead of offering protection, supplemental vitamin E (+selenium) would actually increase the risk of developing cancer. Those of you who have been following my posts for more than the last two weeks, will yet probably remember that this was a similarly single-sided presentation of intrinsically questionable epidemiological data, as the latest upheaval about the life-shortening effects of multi-vitamin pills (cf. "Vitamin E & Cancer?" & "Is Your Multi Killing You?").

In view of the emerging image of the critical role of "inflammation" in the highly beneficial adaptive response to exercise, it may yet still be worth to re-evaluate the cost-benefit ratio of vitamin E supplementation. If we temporarily disregard the discussion that revolves around the use of natural vs. synthetic and isolated vs. complex forms (I would always recommend using a natural supplement with alpha-, gamma- and delta-tocopherol), and focus on the athletic or at least physically active population who is leading an otherwise relatively healthy lifestyle (whatever that may be ;-), we could probably narrow this complex issue down to the question whether or not, and in which contexts, the use of vitamin E to sooth down overall inflammation could turn out to be advantageous.

Sedentary or trained. Does it make a difference?

The first of two pertinent studies, which resurrected my personal interest into this topic has been conducted at the Warsaw University of Life Sciences in Poland (Debski. 2012). It is a 10-day rodent study in which 27 of the 54 vitamin-E deprived young male Wistar rats that were maintained on diets with 0, 0.5, 1.0 and 4.0 mg of alpha-tocopherol (as alpha-tocopherol acetate) per day, had to run on one of those funky rodent treadmills for 15 minutes a day, while the rest of the rats led their usual "sedentary" lives. The intention of the study was to elicit the effect of physical exercise on the vitamin E status and requirements of mammals and its downstream effects on insulin levels - both are issues which would obviously be important for any aspiring physical culturist, as well, since previous research has shown that low alpha-tocopherol levels impair the beneficial effects of physical activity on blood glucose management. On the other hand, you will probably remember my previous blogposts on the research of two German scientists, which suggests that very high doses of anti-oxidants could be similarly detrimental, as they could potentially impair the hormetic response to exercise / stress (cf. "Are You Stressed Enough?" and "Update on Antioxidants and Exercise").
Figure 1: Plasma vitamin E levels (in mg/L) in previously vitamin E deprived rats after 10 days on diets containing 0, 0.5, 1.0 and 4.0mg of alpha-tocopherol acetate (left) and relative change vs. baseline (left; data adapted from Debski. 2012)
If you take a closer look at the differential effects the four different amounts of supplemental vitamin E had on the alpha-tocopherol concentration in the plasma of the lab animals, you may be surprised that despite an initially greater response in the sedentary rodents, the exercised rodents exhibited a more favorable response to the highest doses of vitamin E (4mg for a rat ~1200IU for a human). Although the overall effect of exercise on the plasma level was non-significant (the amount of vitamin E in the diet was the critical determinant), the greater "vitamin E capacity" of the exercised rats could in itself be a "hormetic" response to the low grade stress. And - and this is certainly the data you are waiting for - the beneficial effects on insulin levels were present in all groups, including the high as well as the no supplementation group.

So, vitamin E is not harmful, but useless?

In isolation, the results of the Debski study would thusly support the hypothesis that the beneficial, as well as the potential detrimental effects of vitamin E, which were perpetuated by the lay-press, as of late, are largely overblown. That vitamin E was basically useless... well, if you are a rat, running on a treadmill for 15 minutes a day (which I would say is probably less "exercise" than a natural rat is "supposed to have" < attention: paleo reasoning at work ;-) that may well be the case. If you are a competitive athlete who trains 3-3.5h per day, like the rowers in a study which was recently published in the Journal of Clinical Toxicology, things may be different, however (Sardas. 2012).

Semra Sardas and her (?) colleagues obviously had a similar question in mind when they conducted a study to assess the potentially differential and hopefully beneficial effects of two months (note: for this kind of studies this is a very long and thusly meaningful study period!) of 400IU/day of supplemental alpha-tocopherol on the exercise induced DNA-damage in "recreational active" individuals (physical education students; >1h of exercise min. 2x/week) and the aforementioned competitive rowers.
Figure 2: Relative change in DNA-damage in response to 60 days on 400IU/day vitamin E in competitive rowers (highly trained athletes) and physical education students ("active individuals"; data calculated based on Sardas. 2012)
If you take a look at the relative change in DNA-damage (comparing the pre- vs. post-supplementation period) subsequent to a standardized exercise test (high intensity for the rowers, medium intensity for the students) which was performed at the beginning and the end of the 60-day study period, the first thing that will probably catch your eye are the statistically significant decreases in baseline (pre-exercise) and peak (post exercise) DNA damage in both groups. What may appear to as if it was a source of concern, though is that the relative increase in DNA damage to the acute exercise bout in the rowers was more pronounced after, than before the intervention period.

In view of the fact that the total DNA damage was yet still -9% and thusly statistically significantly reduced, it does not appear likely this would be a consequence of an inadequate ability to adapt to stressors... it is rather a consequence of the profoundly (-25%) reduced baseline DNA-damage, which in itself would suggest that especially highly trained athletes should not discard the potential benefits at least moderate doses of vitamin E could have on their overall health - even if there are no noticeable short-term effects in terms of improved body composition and / or performance... always remember: You are in this for a life-time!