A single oral supplementation of nicotinamide within the daily tolerable upper level increases blood NAD+ levels in healthy subjects

A decrease in nicotinamide adenine dinucleotide (NAD+) levels is a hallmark of aging in multiple species, including humans. Our previous clinical trial showed that supplementation of 200 mg nicotinamide, a form of vitamin B3, increased blood NAD+ levels. Here we report a clinical trial to assess the efficacy of a lower and a higher dose nicotinamide on increasing NAD+ levels. Blood NAD+ levels were evaluated before and after treatment of 100 mg nicotinamide, 500 mg nicotinamide, or water only. The three treatment arms were tested in the same cohort of 5 healthy adults. Oral supplementation of 500 mg nicotinamide led to a significant increase in blood NAD+ after 12 h and showed a trend of increase after 48 h (P = 0.056), whereas 100 mg nicotinamide or water intake only did not change the NAD+ levels in the same subjects. Blood lipidome analysis showed that the levels of 277 lipid species significantly changed after 12 h among 1463 species detected, while no changes were detected at 0 h among the 3 groups. These lipid changes largely reflected the difference between the nicotinamide supplemented groups and the water control group. Together with our previous results, this study shows that oral supplementation of nicotinamide within the daily tolerable upper level is an effective way to transiently increase NAD+ levels and affect the composition of blood lipids.