Blood plasma concentration of NAD⁺ (A) NADH, (B) and total NAD (C), as well as the plasma NAD redox ratio (D) in men and women of a normal human population. Plasma total NAD depending on the median NAD⁺/NADH ratio for men (1.09) and women (1.33) (E). All data are shown as box plot with whiskers and 5^th/95^th percentiles. In E, the subgroups contained n = 45, 46, 64 and 27 men as well as 37, 77, 57 and 57 women (black or with plots from left to right). P values were calculated by the Rank sum test.