As cells become nonfunctional, they produce inflammatory cytokines and compromise tissue health.

An energy-carrying molecule present in all cells. ATP fuels cellular processes, including biosynthetic reactions, motility, and cell division by transferring one or more of its phosphate groups to another molecule (a process called phosphorylation).

A nonessential amino acid that is able to be manufactured by the human body and not dietarily required. It is nevertheless found in a wide variety of foods, and is particularly concentrated in meats.

A neurodegenerative disorder characterized by progressive memory loss, spatial disorientation, cognitive dysfunction, and behavioral changes. The pathological hallmarks of Alzheimer's disease include amyloid-beta plaques, tau tangles, and reduced brain glucose uptake. Most cases of Alzheimer's disease do not run in families and are described as "sporadic." The primary risk factor for sporadic Alzheimer's disease is aging, with prevalence roughly doubling every five years after age 65. Roughly one-third of people aged 85 and older have Alzheimer's. The major genetic risk factor for Alzheimer's is a variant in the apolipoprotein E (APOE) gene called APOE4.

A toxic 42 amino acid peptide that aggregates and forms plaques in the brain with age. Amyloid-beta is associated with Alzheimer's disease, a progressive neurodegenerative disease that can occur in middle or old age and is the most common cause of dementia. Heat shock proteins have been shown to inhibit the early aggregation of amyloid beta 42 and reduce amyloid beta plaque toxicity ^[1].

The physiological process through which new blood vessels form from preexisting vessels. This is a normal and vital process in growth and development, wound healing, and in the formation of granulation tissue. However, it is also a fundamental step in the transition of tumors from a benign state to a malignant one.

The shrinking or wasting away of cells, organs, or tissues that may occur as part of a disease process, trauma, or aging.

An intracellular degradation system involved in the disassembly and recycling of unnecessary or dysfunctional cellular components. Autophagy participates in cell death, a process known as autophagic dell death. Prolonged fasting is a robust initiator of autophagy and may help protect against cancer and even aging by reducing the burden of abnormal cells.

The relationship between autophagy and cancer is complex, however. Autophagy may prevent the survival of pre-malignant cells, but can also be hijacked as a malignant adaptation by cancer, providing a useful means to scavenge resources needed for further growth.

The extent and rate at which drugs or other substances, such as plant-based dietary compounds, enter the body’s circulation. Bioavailability is influenced by a variety of factors, including dose, the presence of other foods or substances, and interindividual differences in metabolism due to gut absorptive surface and commensal microbial populations.

A highly selective semi-permeable barrier in the brain made up of endothelial cells connected by tight junctions. The blood-brain barrier separates the circulating blood from the brain's extracellular fluid in the central nervous system. Whereas water, lipid-soluble molecules, and some gases can pass through the blood-brain barrier via passive diffusion, molecules such as glucose and amino acids that are crucial to neural function enter via selective transport. The barrier prevents the entry of lipophilic substances that may be neurotoxic via an active transport mechanism.

The practice of long-term restriction of dietary intake, typically characterized by a 20 to 50 percent reduction in energy intake below habitual levels. Caloric restriction has been shown to extend lifespan and delay the onset of age-related chronic diseases in a variety of species, including rats, mice, fish, flies, worms, and yeast.

A person who is 100 or more years old.

A substance whose presence is essential for the activity of an enzyme. Many minerals and vitamins are cofactors for enzymes.

A major contributing factor to aging, cellular senescence, and the development of cancer. Byproducts of both mitochondrial energy production and immune activity are major sources of DNA damage. Additionally, environmental stressors can increase this base level of damage. DNA damage can be mitigated by cellular repair processes; however, the effectiveness of these processes may be influenced by the availability of dietary minerals, such as magnesium, and other dietary components, which are needed for proper function of repair enzymes.

Describes the change in effect on an organism caused by differing levels of exposure (or doses) to a stressor. Studying dose response, and developing dose–response models, is central to determining "safe", "hazardous" and (where relevant) beneficial levels and dosages for drugs, pollutants, foods, and other substances to which humans or other organisms are exposed.

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

Genetic control elicited by factors other than modification of the genetic code found in the sequence of DNA. Epigenetic changes determine which genes are being expressed, which in turn may influence disease risk. Some epigenetic changes are heritable.

A molecule composed of carboxylic acid with a long hydrocarbon chain that is either saturated or unsaturated. Fatty acids are important components of cell membranes and are key sources of fuel because they yield large quantities of ATP when metabolized. Most cells can use either glucose or fatty acids for this purpose.

A series of enzyme-dependent reactions that breaks down glucose. Glycolysis converts glucose into pyruvate, releasing energy and producing ATP and NADH. In humans, glycolysis occurs in the cytosol and does not require oxygen.

The years of a person’s life spent free of disease.

A critical element of the body’s immune response. Inflammation occurs when the body is exposed to harmful stimuli, such as pathogens, damaged cells, or irritants. It is a protective response that involves immune cells, cell-signaling proteins, and pro-inflammatory factors. Acute inflammation occurs after minor injuries or infections and is characterized by local redness, swelling, or fever. Chronic inflammation occurs on the cellular level in response to toxins or other stressors and is often “invisible.” It plays a key role in the development of many chronic diseases, including cancer, cardiovascular disease, and diabetes.

A peptide hormone secreted by the beta cells of the pancreatic islets cells. Insulin maintains normal blood glucose levels by facilitating the uptake of glucose into cells; regulating carbohydrate, lipid, and protein metabolism; and promoting cell division and growth. Insulin resistance, a characteristic of type 2 diabetes, is a condition in which normal insulin levels do not produce a biological response, which can lead to high blood glucose levels.

A physiological condition in which cells fail to respond to the normal functions of the hormone insulin. During insulin resistance, the pancreas produces insulin, but the cells in the body become resistant to its actions and are unable to use it as effectively, leading to high blood sugar. Beta cells in the pancreas subsequently increase their production of insulin, further contributing to a high blood insulin level.

Independent of reactive oxidative species, mitochondria become ineffective and compromise energy supply to cells and local tissue as humans get older.

The thousands of biochemical processes that run all of the various cellular processes that produce energy. Since energy generation is so fundamental to all other processes, in some cases the word metabolism may refer more broadly to the sum of all chemical reactions in the cell.

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.

The process by which new mitochondria are made inside cells. Many factors can activate mitochondrial biogenesis including exercise, cold shock, heat shock, fasting, and ketones. Mitochondrial biogenesis is regulated by the transcription factor peroxisome proliferator-activated receptor gamma coactivator 1-alpha, or PGC-1α.

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).

Nicotinamide adenine dinucleotide (NAD) is a coenzyme found in all living cells used to transfer chemical energy from a food source to the electron transport chain. It exists in two forms, an oxidized and reduced form abbreviated as NAD+ and NADH respectively. NAD levels rise during a fasting state and activates the SIRT1 pathway. NADH levels rise during the fed state and serve as reducing equivalents to produce ATP.

Nicotinamide adenine dinucleotide (NAD) is a coenzyme found in all living cells used to transfer chemical energy from a food source to the electron transport chain. It exists in two forms, an oxidized and reduced form abbreviated as NAD+ and NADH respectively. NAD levels rise during a fasting state and activates the SIRT1 pathway. NADH levels rise during the fed state and serve as reducing equivalents to produce ATP.

The process of forming new neurons. Neurogenesis is essential during embryonic development, but also continues in certain brain regions throughout human lifespan.

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 precursor molecule for the biosynthesis of nicotinamide adenine dinucleotide (NAD+), a coenzyme that participates in the production of cellular energy and repair. NMN helps maintain cellular levels of NAD+, thereby facilitating NAD+-dependent cellular activities, such as mitochondrial metabolism, regulation of sirtuins, and PARP activity. Animal studies have demonstrated that NMN administration is effective in increasing NAD+ levels across multiple tissues while improving the outcome of a variety of age-related diseases. Although NMN administration has proven to be safe and to effectively increase NAD+ levels in rodents, the safety and efficacy of NMN supplementation in humans remain unknown. NMN is available in supplement form and is present in various types of food, including broccoli, avocado, and beef. It is also an intermediate compound in the NAD+ salvage pathway, the recycling of nicotinamide into NAD+.

A precursor molecule for the biosynthesis of nicotinamide adenine dinucleotide (NAD+), a coenzyme that participates in the production of cellular energy and repair. NMN helps maintain cellular levels of NAD+, thereby facilitating NAD+-dependent cellular activities, such as mitochondrial metabolism, regulation of sirtuins, and PARP activity. Animal studies have demonstrated that NMN administration is effective in increasing NAD+ levels across multiple tissues while improving the outcome of a variety of age-related diseases. Although NMN administration has proven to be safe and to effectively increase NAD+ levels in rodents, the safety and efficacy of NMN supplementation in humans remain unknown. NMN is available in supplement form and is present in various types of food, including broccoli, avocado, and beef. It is also an intermediate compound in the NAD+ salvage pathway, the recycling of nicotinamide into NAD+.

One of four nitrogen-containing molecules that comprise DNA. A nucleotide consists of one of four chemicals, called a “base,” plus one molecule of sugar and one molecule of phosphoric acid. Nucleotides are typically identified by the first letter of their base names: adenine (A), cytosine (C), guanine (G), and thymine (T). They form specific pairs (A with T, and G with C), and their bonds provide the helical structure of the DNA strand.

A chemical reaction in which an atom, molecule, or ion loses one or more electrons. Oxidation of biological molecules is associated with oxidative stress, a key driver of many chronic diseases.

A neurodegenerative disorder that affects the central nervous system. Parkinson’s disease is caused by destruction of nerve cells in the part of the brain called the substantia nigra. It typically manifests later in life and is characterized by tremors and a shuffling gait.

The observable physical characteristics of an organism. Phenotype traits include height, weight, metabolic profile, and disease state. An individual’s phenotype is determined by both genetic and environmental factors.

A family of proteins involved in a number of cellular processes such as DNA repair, genomic stability, and programmed cell death (apoptosis). PARP's primary role is to detect and initiate an immediate cellular response to metabolic, chemical, or radiation-induced single-strand DNA breaks by signaling the enzymatic machinery involved in repair. NAD+ is required as substrate for generating ADP-ribose monomers. Evidence suggests that overactivation of PARP may deplete cellular stores of NAD+.

A portmanteau of the words protein and homeostasis. Proteostasis is maintained through the competing and integrated biological pathways within cells that control the biogenesis, folding, trafficking and degradation of proteins present within and outside the cell. Proteostasis deteriorates with age. As a result, the prevalence of age-related protein misfolding diseases, such as Alzheimer’s disease and Parkinson’s disease, increases.

A chemical reaction in which an atom, molecule, or ion gains one or more electrons.

Alternating chemical processes of reduction (gain of electrons) and oxidation (loss of electrons) – commonly referred to as “redox” reactions. Redox reactions occur simultaneously and are essential for the execution of many metabolic pathways.

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 main-step process resuming in the net movement of cholesterol from peripheral tissues back to the liver via the plasma. Excess cholesterol from cells is brought back to the liver by HDL where it is secreted in bile or otherwise converted into bile salts.

Senescence is a response to stress in which damaged cells suspend normal growth and metabolism. While senescence is vital for embryonic development, wound healing, and cancer immunity, accumulation of senescent cells causes increases inflammation and participates in the phenotype of aging.

A member of the sirtuin protein family. SIRT1 is an enzyme that deacetylates proteins that contribute to cellular regulation (reaction to stressors, longevity). It is activated by the phytochemical resveratrol as well as fasting.

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.

A cell that has the potential to develop into different types of cells in the body. Stem cells are undifferentiated, so they cannot do specific functions in the body. Instead, they have the potential to become specialized cells, such as muscle cells, blood cells, and brain cells. As such, they serve as a repair system for the body. Stem cells can divide and renew themselves over a long time. In 2006, scientists reverted somatic cells into stem cells by introducing Oct4, Sox2, Klf4, and cMyc (OSKM), known as Yamanaka factors.^[1]

An essential amino acid. Tryptophan plays key roles in the biosynthesis of proteins and is a precursor to several molecules with physiological significance, including melatonin, niacin, and the neurotransmitter serotonin. Inflammation causes tryptophan to be reallocated from serotonin synthesis to that of kynurenine, which then converts to the neurotoxin quinolinic acid, leading to depression. Dietary sources of tryptophan include most protein-based foods, such as meat, beans, or nuts.