Science of NAD+
Function of NAD+
NAD+ (Nicotinamide Adenine Dinucleotide) is an essential cofactor for enzymes that control the metabolic activity in your cells. Changes in NAD+ levels lead to changes in the functioning of mitochondria, which are the cell’s energy producing organs. Age associated decreases in NAD+ levels cause diminished mitochondrial energy production, leading to metabolic disorders like type-2 diabetes, and non-alcoholic fatty liver disease. NAD+ is also an essential cofactor for enzymes that control DNA repair (enzymes called PARPs), and cellular metabolism (enzymes call Sirtuins).
Low NAD+ in Disease States
Impaired NAD+ mediated Sirtuin signaling in the cell is implicated in the development of insulin resistance and type-2 diabetes [1-7], as well as non-alcoholic fatty liver disease (NAFLD). NAFLD is the most common liver disease in the Western World, leading to inflammation that can progress to cirrhosis or liver cancer. Zhou et al.  showed that liver NAD+ levels decline with aging in humans. Evidence suggests that decreased NAD+ dependent Sirtuin action contributes to the formation of NAFLD [9-13]. Human studies are currently being designed to investigate replenishing liver NAD+ levels, thus activating Sirtuins to reverse metabolic dysfunction at the root of NAFLD.
Role of NAD+ in Aging
As we age, NAD+ levels progressively decrease which contributes to the general decline associated with aging [14-15]. Inflammation and oxidation further reduce levels of NAD+ which, in turn, reduces Sirtuin activity. Together, NAD+ and Sirtuins regulate numerous pathways that control our aging and lifespan[17-19]. Mammals contain seven Sirtuin enzymes (SIRT1–7) that have a wide variety of biological functions including control of cellular metabolism and energy, aging and longevity, cell survival, DNA repair, and stress resistance. Boosting cellular NAD+ levels serves as a powerful means to activate Sirtuins, and as a potential therapy for age-related disorders and the general decline associated with aging.
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