Acute nicotinamide riboside supplementation improves redox homeostasis and exercise performance in old individuals: a double-blind cross-over study.

Older individuals suffer from low NADH levels. We have previously shown that nicotinamide riboside [NR; a NAD(P)(H) precursor] administration impaired exercise performance in young rats. It has been suggested that supplementation of redox agents exerts ergogenic effect only in deficient individuals. We hypothesized that old individuals would more likely benefit from NR supplementation. We investigated the effect of acute NR supplementation on redox homeostasis and physical performance in young and old individuals.

Twelve young and twelve old men received NR or placebo in a double-blind cross-over design. Before and 2 h after NR or placebo supplementation, blood and urine samples were collected, while physical performance (VO_2max, muscle strength, and fatigue) was assessed after the second blood sample collection.

At rest, old individuals exhibited lower erythrocyte NAD(P)H levels, higher urine F₂-isoprostanes and lower erythrocyte glutathione levels compared to young (P < 0.05). NR supplementation increased NADH (51% young; 59% old) and NADPH (32% young; 38% old) levels in both groups (P < 0.05), decreased F₂-isoprostanes by 18% (P < 0.05), and tended to increase glutathione (P = 0.078) only in the old. NR supplementation did not affect VO_2max and concentric peak torque, but improved isometric peak torque by 8% (P = 0.048) and the fatigue index by 15% (P = 0.012) in the old. In contrast, NR supplementation did not exert any redox or physiological effect in the young.

NR supplementation increased NAD(P)H levels, decreased oxidative stress, and improved physical performance only in old subjects, substantiating that redox supplementation may be beneficial only in individuals with antioxidant deficiencies.