Nicotinamide riboside supplementation dysregulates redox and energy metabolism in rats: Implications for exercise performance

Nicotinamide riboside is a recently discovered form of vitaminB(3) 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 [300mg(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 F-2-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.