Any of a group of complex proteins or conjugated proteins that are produced by living cells and act as catalyst in specific biochemical reactions.

Tiny organelles inside cells that produce energy in the presence of oxygen. Mitochondria are referred to as the "powerhouses of the cell" because of their role in the production of ATP (adenosine triphosphate). Mitochondria are continuously undergoing a process of self-renewal known as mitophagy in order to repair damage that occurs during their energy-generating activities.

Dietary supplements that purportedly increase cellular levels of nicotinamide adenine dinucleotide (NAD+). Examples of potential NAD+ boosters include resveratrol (a plant-based dietary compound found in grapes), metformin (a type of diabetes medication), and nicotinamide mononucleotide (a derivative of niacin).

A coenzyme that is required for the production of energy in cells. NAD+ is synthesized from three major precursors: tryptophan, nicotinic acid (vitamin B3), and nicotinamide. It regulates the activity of several key enzymes including those involved in metabolism and repairing DNA damage. NAD+ levels rise during a fasted state. A group of enzymes called sirtuins, which are a type of histone deacetylase, use NAD+ to remove acetyl groups from proteins and are important mediators for the effects of fasting, caloric restriction, and the effects of the plant compound resveratrol, a so-called caloric restriction mimetic.

A polyphenolic compound produced in plants in response to injury or pathogenic attack from bacteria or fungi. Resveratrol exerts a diverse array of biological effects, including antitumor, antioxidant, antiviral, and hormonal activities. It activates sirtuin 1 (SIRT1), an enzyme that deacetylates proteins and contributes to cellular regulation (including autophagy). Dietary sources of resveratrol include grapes, blueberries, raspberries, and mulberries.

Resveratrol Autophagy ↑ Deacetylases (especially SIRT1) → ↓ Protein Acetylation → Autophagy

A class of enzymes that influence that influence aging and longevity through multiple molecular pathways. Sirtuins regulate a variety of metabolic processes, including release of insulin, mobilization of lipids, response to stress, and modulation of lifespan. They also influence circadian clocks and mitochondrial biogenesis. Sirtuins are activated when NAD+ levels rise. The dependence of sirtuins on NAD+ links their enzymatic activity directly to the energy status of the cell via the cellular NAD+:NADH ratio, the absolute levels of NAD+, NADH or nicotinamide or a combination of these variables. There are seven known sirtuins, designated as Sirt1 to Sirt7.