Glossary

Longevity and wellness terms, explained simply

37 essential terms across longevity, genetics, performance and biohacking — each with a one-sentence definition, context and links to go deeper.

Quick answer

Why learn longevity terminology?

Understanding a handful of key terms — like methylation, biological age, HRV and VO₂ max — makes research, lab reports and genetic results far easier to interpret, so you can ask better questions and make more confident decisions with your healthcare team.

A

Allostatic loadPerformance: Allostatic load is the cumulative wear and tear on the body caused by repeated or chronic stress and the effort of adapting to it.
AutophagyLongevity: Autophagy is the cell's recycling system — the process of breaking down and reusing damaged or unneeded cellular components.

B

Biological ageLongevity: Biological age is an estimate of how old your body seems based on biomarkers such as DNA methylation, blood chemistry or physical performance, rather than your date of birth.

C

Cellular senescenceLongevity: Cellular senescence is a state in which cells permanently stop dividing but remain metabolically active, often releasing inflammatory signals.
ChronotypePerformance: A chronotype is your natural preference for the timing of sleep and activity — often described as morning type (“lark”), evening type (“owl”) or in between.
Circadian rhythmBiohacking: The circadian rhythm is your body's roughly 24-hour internal clock that regulates sleep, alertness, hormone release, body temperature and metabolism.
COMTGenetics: COMT (catechol-O-methyltransferase) is an enzyme that uses methyl groups to break down catecholamines such as dopamine, adrenaline and noradrenaline, as well as catechol estrogens.
CortisolPerformance: Cortisol is a hormone produced by the adrenal glands that helps regulate the stress response, blood sugar, inflammation and the sleep-wake cycle.
CYP1A2Genetics: CYP1A2 is a liver enzyme responsible for metabolizing most of the caffeine you consume; genetic variants influence whether you clear caffeine faster or slower.

D

DNA methylationGenetics: DNA methylation is the addition of methyl groups to DNA — usually at cytosine bases — which helps regulate whether genes are switched on or off without changing the DNA sequence.

E

EpigeneticsGenetics: Epigenetics is the study of changes in gene activity that don't involve changes to the DNA sequence itself — such as DNA methylation and histone modifications.

F

FolateGenetics: Folate (vitamin B9) is a B vitamin essential for DNA synthesis, cell division and the methylation cycle; it's found naturally in leafy greens, legumes and other foods.

G

GenotypeGenetics: A genotype is the specific combination of gene variants (alleles) you carry at a given location in your DNA — one inherited from each parent.
GlutathioneLongevity: Glutathione is a major antioxidant made in the body from cysteine, glutamate and glycine; it helps neutralize reactive molecules and supports detoxification.
Gut microbiomeLongevity: The gut microbiome is the community of trillions of bacteria, fungi and other microbes living in the digestive tract, along with their genes and metabolic activity.

H

Hallmarks of agingLongevity: The hallmarks of aging are a scientific framework describing the core biological processes that drive aging — updated in 2023 to twelve hallmarks.
Heart rate variability (HRV)Performance: Heart rate variability is the variation in time between heartbeats; it reflects the balance of your autonomic nervous system and is widely used to track recovery and stress.
HomocysteineGenetics: Homocysteine is an amino acid produced during methylation; it's recycled using folate, B12 and betaine or converted with vitamin B6, and elevated levels are associated with cardiovascular and cognitive concerns.
HormesisBiohacking: Hormesis is a biological response in which a low or moderate dose of a stressor triggers beneficial adaptations, while higher doses can be harmful.

M

MelatoninBiohacking: Melatonin is a hormone released by the pineal gland in darkness that signals nighttime to the body and helps regulate the timing of sleep.
MethylationGenetics: Methylation is the transfer of a methyl group (one carbon and three hydrogens) onto DNA, proteins or other molecules; it regulates genes, recycles homocysteine and helps make neurotransmitters and creatine.
MethylfolateGenetics: Methylfolate (5-methyltetrahydrofolate) is the active form of folate that donates a methyl group to recycle homocysteine into methionine.
MitochondriaLongevity: Mitochondria are structures inside cells that produce most of the body's energy (ATP) from nutrients and oxygen; they also regulate signaling and cell death.
MTHFRGenetics: MTHFR is a gene that encodes the enzyme methylenetetrahydrofolate reductase, which converts folate into its active form (5-MTHF) for homocysteine recycling.

N

NAD+Longevity: NAD+ (nicotinamide adenine dinucleotide) is a coenzyme found in every cell that is essential for energy metabolism, DNA repair and the activity of sirtuin enzymes.
NutrigenomicsGenetics: Nutrigenomics is the study of how genes and nutrients interact — how genetic variants influence nutrient needs and responses, and how diet influences gene expression.

O

Oxidative stressLongevity: Oxidative stress is an imbalance between reactive oxygen species (free radicals) and the body's antioxidant defenses, which can damage cells when sustained.

P

PhotobiomodulationBiohacking: Photobiomodulation is the use of low-level red and near-infrared light to influence cellular function, commonly known as red light therapy.

R

REM sleepBiohacking: REM (rapid eye movement) sleep is a sleep stage characterized by vivid dreaming, rapid eye movements and temporary muscle paralysis; it supports emotional processing and memory.

S

SAMeGenetics: SAMe (S-adenosylmethionine) is the body's main methyl donor, made from the amino acid methionine and used in hundreds of methylation reactions.
Short-chain fatty acidsLongevity: Short-chain fatty acids — mainly acetate, propionate and butyrate — are produced when gut bacteria ferment dietary fiber; they nourish colon cells and influence metabolism and immunity.
Slow-wave sleepBiohacking: Slow-wave sleep (N3, or deep sleep) is the deepest stage of non-REM sleep, associated with physical restoration, growth hormone release and memory consolidation.
SNPGenetics: A SNP (single-nucleotide polymorphism) is a variation at a single position in the DNA sequence — the most common type of genetic variation between people.

T

TelomeresLongevity: Telomeres are protective caps at the ends of chromosomes that shorten with each cell division; very short telomeres can trigger cell senescence.
TMG (trimethylglycine)Genetics: TMG (trimethylglycine), also called betaine, is a methyl donor that helps convert homocysteine into methionine through the BHMT pathway.

V

VO₂ maxPerformance: VO₂ max is the maximum rate at which your body can take in and use oxygen during intense exercise — a key measure of cardiorespiratory fitness.

Z

Zone 2 trainingPerformance: Zone 2 training is steady, low-to-moderate intensity aerobic exercise — typically a pace where you can still hold a conversation — used to build aerobic base and mitochondrial capacity.

FAQ

Glossary FAQs

What is the Live10X glossary?

Plain-English definitions of longevity, genetics and performance terms — from methylation and MTHFR to VO2 max and autophagy — each linked to the guides where the term matters.

How should I use a glossary definition?

Start with the one-sentence definition, then follow the links to the full guide for context, evidence and practical steps.

Are glossary entries medical advice?

No. Definitions are educational. Talk with a qualified professional about how any term applies to your health.

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