Background
Oxidative stress is an imbalance between antioxidant system and production of free radicals and has been associated with the age‐related deleterious changes. The defense system can be modulated by exercise and nutrition.
Objective
The purpose of this investigation was to evaluate the effect of whey protein supplementation pre‐ or post‐resistance training on oxidative stress and antioxidant enzyme activity in pre‐conditioned older women.
Methods
In a randomized, double‐blind, and placebo‐controlled design, 70 older women (≥60 years) were randomly assigned to one of the following three groups: whey protein‐placebo (WP‐PLA, n = 24), placebo‐whey protein (PLA‐WP, n = 23), and placebo‐placebo (PLA‐PLA, n = 23). Each group received 35 g of whey product or placebo pre‐ and post‐training. The RT program was carried out over 12 weeks (3x/week; 3x 8‐12 repetitions maximal). Oxidative stress and blood markers were assessed before and after intervention period. ANOVA for repeated measures was used for data analysis.
Results
There was a significant time effect (P < 0.05), with all groups showing improvements in all oxidative stress markers and antioxidant enzyme activity. A significant (P < 0.001) interaction time vs group was observed for uric acid, with both WP‐PLA and PLA‐WP presenting greater reductions compared with the PLA‐PLA, without differences between the timing of protein intake (WP‐PLA: −8.3%; PLA‐WP: −11.0%; PLA‐PLA:‐2.0%).
Conclusion
In already pre‐conditioned older women, whey protein supplementation reduces plasma uric acid concentration with no further effect on antioxidant enzyme activity and oxidative stress markers. ClinicalTrials.gov: NCT03247192.