Effects of 8 Weeks of Combined Exercise and a Vegetarian Diet on the Antioxidant System and Metabolic Flexibility

Abstract

Regular exercise and a vegetarian diet have each been suggested to have antioxidant effects. However, the additional benefits of combining exercise with a vegetarian diet remain unclear. The purpose of this study is to examine the effects of combined exercise and a vegetarian diet on the antioxidant system and metabolic flexibility. Thirty healthy adults were selected and randomly assigned to one of four groups: a control (CON) group, a vegetarian diet (VD) group, an exercise (EX) group, and a group following both a vegetarian diet and exercise regimen (VDEX). The combined exercise, consisting of resistance and endurance training, was performed three times per week for eight weeks, while the vegetarian diet intervention followed a lacto-ovo diet for the same period. Blood samples were collected at pre- and post-intervention stages to analyze serum levels of sirtuin 3 (Sirt3), superoxide dismutase 2 (SOD2), and malondialdehyde (MDA). To evaluate metabolic flexibility, carbohydrate and fat oxidation rates, as well as lactate levels, were measured during a graded exercise test. Postintervention, serum Sirt3 and SOD2 levels significantly increased in both the EX and VDEX groups (p < 0.05), while serum MDA levels significantly decreased (p < 0.05). Additionally, during the post-intervention graded exercise test, carbohydrate oxidation rates and lactate levels significantly decreased in the EX and VDEX groups (p < 0.05), while fat oxidation rates significantly increased (p < 0.05). These results suggest that combined exercise may be effective in reducing oxidative stress by enhancing antioxidant capacity and may also positively influence metabolic flexibility. However, the antioxidant effects of the vegetarian diet alone were not observed.