Study: Antioxidant supplements (still) not an athlete’s best training partner

By Adi Menayang contact

- Last updated on GMT

Photo: iStock
Photo: iStock
Back in 2009, a group of researchers in Germany and the US published a hotly debated study that said antioxidants may blunt the benefits of exercise. One of the researchers recently released a topical review of the subject, and he still stands by the results.

“The evidence presented in this review suggests that antioxidants have the potential to suppress some exercise training adaptations, and provides little evidence to suggest any positive effects, therefore [we] tend to reject the use of such supplements during training,” ​Dr. Troy Merry of the University of Auckland, who co-authored the topical review​, told NutraIngredients-USA.

Dr. Merry’s co-author for this topical review was Dr. Michael Ristow of the Swiss Federal Institute of Technology in Zurich (ETH Zurich), one of the authors of a 2009 study​ that revealed antioxidants’ deleterious effects to exercise, garnering much media fanfare and criticism from the supplements industry.

While researching for the review, the two narrowed down sources to “studies that have utilized supplements whose primary function is ROS or RNS prevention,” ​Dr. Merry said.

Because of that, they didn’t use any studies involving polyphenols and flavonoids with anti-oxidant properties (like resveratrol or epigallocatechin gallate) in their review.

More harm than good?

Through secondary research, the authors wrote that taking supplements such as vitamins C and E may hamper the normal skeletal muscle adaptation process—contrary to the popular belief that it reduces the ROS levels induced by exercise.

It does have its benefits—such as aiding recovery, muscle damage, and reducing fatigue. But the negative affects—angiogenesis, insulin sensitivity, cellular defenses, hypertrophy, and mitochondrial biogenesis—far outnumber the good.

“Antioxidant supplementation has been more consistently reported to have deleterious effects on the response to overload stress and high-intensity training,”​ Dr. Merry said. “This suggests that remodeling of skeletal muscle following resistance and high-intensity exercise is more dependent on ROS/RNS signaling.”

But exercise itself is an antioxidant​, doing so by regulating endogenous antioxidant defense, and the natural antioxidant effect of exercise is “likely to be one of the mechanisms underlying the health-promoting benefits of regular exercise,”​ the writers contend.

But the when it comes to antioxidant supplementation, tests have revealed there is no effect on the incidence of disease in humans​, sometimes even increasing the chances of disease. “The answer may relate to the types of antioxidants supplemented, which are normally generalized, non-target scavengers of all ROS such as vitamin C and E,”​ they wrote.

An option for tournaments

Despite the negative effects outlined in this review, Dr. Merry said that it “does not preclude the use of antioxidant supplements during competition where performance is the priority and adaptive responses are irrelevant.”

The authors cited a 2011 study​ that noticed how, in general, reports of antioxidants improving performance happened in studies that employed “fatiguing-type exercise and supplementation either immediately before or during exercise, while the adverse effect of antioxidants on performance are more commonly associated with longer duration (several days or longer) supplementation protocols.”

Both Dr. Ristow and Dr. Merry concluded that because antioxidant supplementation’s effect on skeletal muscle adaptation is still equivocal, they cannot recommend supplementation to be part of a training program.

“It is theoretically possible that antioxidants may aid exercise if the exercise stress was sufficient to chronically elevate ROS to levels which impair function and cause damage,” ​the authors wrote. “However, it is unlikely that such levels would be achieves solely through exercise training.”

Source: The Journal of Physiology

First published online, doi: 10.1113/JP270654

Do antioxidant supplements interfere with skeletal muscle adaptation to exercise training?

By: Merry, Troy L., Ristow, M.

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