Fig. 3.

Niacin’s mechanism of action explained by raising NAD⁺ levels? As a precursor for NAD⁺, niacin can activate the deacylase SIRT1, which might explain niacin’s beneficial effects on lipid homeostasis. First, SIRT1 activates PGC-1α, which leads to increased mitochondrial activity and FA oxidation. Moreover, SIRT1 activates LXR, which leads to increased expression of ABCA1, and thus increased circulating HDL particles. Furthermore, SIRT1 destabilizes SREBPs and thereby lowers SREBP-mediated FA, TG, and cholesterol synthesis and circulation.