The Vitamin E Consumption Effect on Muscle Damage and Oxidative Stress: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Abstract

Introduction: Vitamin E supplementation may protect against exercise-induced muscle damage (EIMD) through possible inhibition of free radical formation and cell membrane stabilization. However, there is no systematic review of this topic. This fact maintains academic stalemates that may have a resolution. Objective: This systematic review with meta-analysis aims to provide a comprehensive literature review on the hypothesis of the benefit of vitamin E supplementation on oxidative stress and muscle damage induced by aerobic exercise. Methods: A random-effects model was used, weighted mean difference (WMD) and 95% confidence interval (CI) were applied to estimate the overall effect. Results: The results revealed a significant effect of vitamin E supplementation on reducing creatine kinase (CK) and lactate dehydrogenase (LDH). In addition, a subgroup analysis resulted in a significant decrease in CK concentrations in trials with immediate and <24 hours post-exercise CK measurement; <1000 at daily vitamin E intake; ≤1 at weekly intake; 1 at six weeks and >6 weeks experimental duration, studies on aerobic exercise and training were part of the crossover study. Conclusion: Vitamin E can be seen as a priority agent for recovery from muscle damage. Evidence Level II; Therapeutic Studies – Investigating the results.

Vitamin E Does not Favor Recovery After Exercises: Systematic Review and Meta-analysis

“…However, recent systematic reviews that evaluated the effects of tocopherols during exercise demonstrated an attenuation of muscle damage (CK and LDH) [27] immediately after exercise (0 h) and in athletes who used vitamin E doses lower than 500 IU [23]. The same happened to healthy individuals supplemented with doses of less than 1000 IU, immediately and < 24 h after exercise, between 1-6 weeks, and > 6 weeks of study duration (subgroup analysis), but the values of the results of these analyses were not presented [27]. As previously described, the aforementioned meta-analyses [23] presents inclusion criteria for studies and data analysis different from the present study.…”

“…Previous meta-analysis using vitamins E [19] also did not find favorable results for this outcome. However, recent systematic reviews that evaluated the effects of tocopherols during exercise demonstrated an attenuation of muscle damage (CK and LDH) [27] immediately after exercise (0 h) and in athletes who used vitamin E doses lower than 500 IU [23]. The same happened to healthy individuals supplemented with doses of less than 1000 IU, immediately and < 24 h after exercise, between 1-6 weeks, and > 6 weeks of study duration (subgroup analysis), but the values of the results of these analyses were not presented [27].…”

“…On the other hand, recent meta-analyses [23] showed that vitamin E supplementation (less than 500 IU and 1000 IU) had a protective effect on muscle damage (creatine kinase -CK and LDH) after exercise. Although supplementation appeared to be effective in these cases, these studies have some limitations, with the inclusion of different forms of vitamin E supplementation [18], the inclusion of clinical trials not placebo-controlled, the uncertainty of the quality of the evidence in addition to meta-analyses that repeated the same sample (multiple times) [23] within a single anal-ysis, or even demonstrating attenuation of muscle damage (CK) in general through subgroup analysis [27]. To date, the effects of isolated vitamin E (α-tocopherol) supplementation, respecting the clearance of this antioxidant on OS, inflammatory markers, muscle damage, soreness, and strength have not been adequately systematically reviewed.…”