Adenosine 5′-triphosphate (ATP) is the primary energy carrier in cells. It’s often called the "energy currency" of the cell, as it stores and transfers energy required for cellular activities. ATP acts like a rechargeable battery: energy can be stored in its high-energy phosphate bonds and released when needed to power various cellular functions, such as muscle contraction, protein synthesis, and cellular division.

A biochemical process that cells use to convert nutrients, primarily glucose, into cellular energy (ATP). NAD+ and NADH are central to this process, enabling efficient energy production through the electron transport chain in mitochondria.

A small molecule that assists enzymes in catalyzing biochemical reactions. Unlike enzymes, coenzymes cannot carry out reactions independently but enhance the enzyme’s activity by binding to the enzyme, forming an active complex.

Enzymes are large, complex proteins that speed up biochemical reactions by acting as catalysts, lowering the activation energy required for reactions to occur. They can either build up (synthesize) or break down (catabolize) molecules called substrates.

Key biological processes and changes that contribute to aging and age-related diseases. These include DNA damage, mitochondrial dysfunction, cellular senescence, loss of proteostasis (protein maintenance), stem cell exhaustion, and changes in cellular communication, among others. See Lopez-Otin et al., 2023. These hallmarks are interconnected and drive the gradual decline in the body’s ability to repair and maintain itself as we age.

The portion of an individual’s life during which they remain physically and mentally healthy. Unlike lifespan, which refers only to the total years lived, healthspan emphasizes the quality of those years. Increasing healthspan focuses on maintaining vitality and functional independence as people age, aiming for a longer, healthier life.

The length of time an organism, cell, or biological system continues to function from its origin to the end of its existence. In human health, lifespan typically refers to the total number of years a person lives, often influenced by genetics, lifestyle, environment, and access to healthcare.

The sum of all the chemical processes that occur within a living organism to maintain life. It includes both catabolic reactions (breaking down molecules to release energy) and anabolic reactions (using energy to build complex molecules).

Any substance that is produced or used during metabolism.

Membrane-bound organelles found in most cells. Known as the “powerhouse” of the cell, mitochondria generate cellular energy (in the form of ATP) through cellular respiration, a process that converts energy stored in food into usable cellular energy.

A form of vitamin B3 that serves as a precursor to NAD+. It helps in the production of NAD+ but causes flushing of the skin. This vitamin is found in many other forms, such as niacinamide/nicotinamide and nicotinamide riboside, which are discussed in more detail below.

A form of vitamin B3 that serves as a precursor to NAD+. Unlike niacin, NAM supplementation does not cause flushing, but has been shown to inhibit sirtuins.

A critical molecule present in all living cells, acting as a coenzyme in various biochemical reactions. It exists in two forms: NAD+ (the oxidized form) and NADH (the reduced form). NAD+ helps cells produce energy by carrying electrons in chemical reactions, especially in processes like cellular respiration, where it supports the production of cellular energy (in the form of ATP). NADH, the reduced form, carries the electrons and is used in different reactions to generate energy. NAD+ and NADH work together in cycles to maintain cellular energy balance, regulate DNA repair, and control aging processes.

A precursor to NAD+ that must be converted into NR before it can enter cells, as it cannot pass through the cell membrane directly.

A form of vitamin B3 that serves as a precursor to NAD+. NR is the most efficient precursor to NAD+ and can directly enter cells.

A substance that is used to make another substance in a chemical process. For example, NAD+ precursors like nicotinamide riboside (NR) and niacin (NA) are molecules that the body can convert into NAD+.

Unstable molecules that contain oxygen and can easily react with other molecules. While ROS are natural byproducts of metabolism, too many of them can damage cells and cellular structures, including DNA, RNA, and proteins, potentially leading to cell death. ROS are also known as free radicals.

A family of enzymes that occur in all living organisms and are thought to regulate cellular aging, apoptosis, and resistance to stress in more complex eukaryotic organisms.