This is yet another confirmation of my suspicion that sedative substances lower cortisol levels. Niacinamide is officially recognized as a GABA-A agonist, but apparently this is not the major reason behind its effect on cortisol. The enzyme that de-activates cortisol – 11b-HSD2 – is apparently an NAD-dependent enzyme. On the other hand, the enzyme that converts cortisone into the active cortisol – 11b-HSD1 – is apperently sensitive to inhibtion by agents that are structurally similar to niacinamide.
