ABSTRACT
PURPOSE: 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. METHODS: 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 (VO2max, muscle strength, and fatigue) was assessed after the second blood sample collection. RESULTS: 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 VO2max 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. CONCLUSIONS: 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.
Subject(s)
Dietary Supplements , Homeostasis/drug effects , Niacinamide/analogs & derivatives , Oxidative Stress/drug effects , Physical Endurance/drug effects , Adult , Age Factors , Aged , Animals , Cross-Over Studies , Disease Models, Animal , Double-Blind Method , Humans , Male , Niacinamide/administration & dosage , Niacinamide/pharmacology , Oxidation-Reduction , Physical Endurance/physiology , Pyridinium Compounds , Young AdultABSTRACT
NEW FINDINGS: What is the central question of this study? The aim was to investigate the potential metabolic and redox mechanisms that impaired exercise performance after 21 days of supplementation with 300 mg (kg body weight)-1 of nicotinamide riboside in rats. What is the main finding and its importance? Nicotinamide riboside disturbed energy and redox metabolism and impaired exercise performance in heathy rats. Exogenously administered redox agents in heathy populations might lead to adverse effects. ABSTRACT: Nicotinamide riboside is a recently discovered form of vitamin B3 that can increase NAD(P) levels. NAD(P) plays key roles in energy metabolism, and its main function is the transfer of electrons in various cellular reactions. Research in aged or diseased mice reported that nicotinamide riboside increases NAD(H) levels, reduces morbidity and improves health and muscle function. We have recently shown that in healthy young rats, chronic administration of nicotinamide riboside marginally non-significantly decreased exercise performance by 35% (P = 0.071). As a follow-up to this finding, we analysed samples from these animals, in an attempt to reveal the potential mechanisms driving this adverse effect, focusing on redox homeostasis and bioenergetics. Thirty-eight Wistar rats were divided into four groups: control (n = 10), exercise (n = 9), nicotinamide riboside (n = 10) and exercise plus nicotinamide riboside (n = 9). Nicotinamide riboside was administered for 21 days [300 mg (kg body weight)-1 daily]. At the end of administration, the exercise and the exercise plus nicotinamide riboside groups performed an incremental swimming performance test until exhaustion. Nicotinamide riboside supplementation increased the levels of NADPH in the liver (P = 0.050), increased the levels of F2 -isoprostanes in plasma (P = 0.047), decreased the activity of glutathione peroxidase (P = 0.017), glutathione reductase (P < 0.001) and catalase (P = 0.024) in erythrocytes, increased the level of glycogen in the liver (P < 0.001) and decreased the concentration of glucose (P = 0.016) and maximal lactate accumulation in plasma (P = 0.084). These findings support the prevailing idea that exogenously administered redox agents in heathy populations might lead to adverse effects and not necessarily to beneficial or neutral effects.
