Exogenous NAD+ source to combat mitochondrial aging? A single dose (1X) of nicotinamide riboside and pterostilbene increased plasma NAD+ levels by 40% and a double dose (2X) by 90% after 4 weeks (compared to placebo). NAD+ is a cofactor for many metabolic enzymes and becomes depleted across various tissues as we age. This causes the mitochondria to suffer and mitochondrial decay is also thought to also be a key driver of aging. Three other blood biomarkers also showed differences that reached statistical significance. First, diastolic blood pressure was significantly reduced at day 60 in the NRPT 1X group. Second, the liver enzyme ALT showed a significant decrease in the NRPT 1X group at both day 30 and day 60. Third, a small increase in total and LDL cholesterol was observed in the NRPT 1X group at day 60 and larger increases in the NRPT 2X groups.