Glossary

Apolipoprotein B. Protein on atherogenic lipoprotein particles (LDL, VLDL, Lp(a)). Particle count, not cholesterol mass, is the causal driver of atherosclerosis; ApoB is often a better cardiovascular risk marker than LDL-C alone.

See: LDL-CLp(a)

Area under the (plasma concentration vs time) curve. A pharmacokinetic measure of total drug exposure after a dose.

See: CmaxHalf-life

Cellular recycling process where damaged organelles and misfolded proteins are broken down. Upregulated by fasting, caloric restriction, and mTORC1 inhibition.

See: rapamycin

Bacteriostatic water for injection. Water containing 0.9% benzyl alcohol to inhibit bacterial growth; used to reconstitute lyophilized peptides.

See: Reconstitution

Brain-derived neurotrophic factor. Protein supporting neuron survival, growth, and synaptic plasticity. Upregulated by aerobic exercise, BDNF polymorphism (Val66Met) modulates response.

See: Neurogenesis

Fraction of an administered dose that reaches systemic circulation unchanged. Oral bioavailability is often reduced by first-pass hepatic metabolism; intravenous bioavailability is 100% by definition.

Coronary artery calcium score. Non-contrast CT quantifying calcified plaque burden. Strong long-term cardiovascular event predictor; score of 0 carries very low 10-year risk.

Chemical Abstracts Service registry number. Unique numeric identifier for a chemical substance.

See: PubChem CID

Continuous glucose monitor. Sensor measuring interstitial glucose every 1-5 minutes; used in biohacking to observe meal responses and glycemic variability in non-diabetics.

Peak plasma concentration of a drug after a single dose. Together with Tmax (time to peak) and half-life, it defines the short-term PK profile.

See: AUCHalf-life

Certificate of analysis. Third-party lab test documenting identity, purity, and potency of a raw ingredient or finished product; standard trust signal for research-use compounds.

Planned on/off administration schedule for a compound. Cycling is used to preserve receptor sensitivity (caffeine, stimulants), restore HPA-axis function (SARMs), or limit cumulative exposure (rapamycin).

Dual-energy X-ray absorptiometry. Imaging modality that quantifies bone mineral density, lean mass, and fat mass with high precision.

Dehydroepiandrosterone. Adrenal steroid and precursor to both testosterone and estradiol. Serum levels decline ~2-3% per year after age 30.

DNA methylation age. Algorithmic estimate of biological age from CpG methylation patterns. Horvath, Hannum, PhenoAge, and GrimAge are the four canonical clocks.

See: PhenoAgeGrimAgeHorvath clock

Digital object identifier. Persistent URL-forwarding identifier for a published paper. Format: 10.xxxx/xxxxx; resolvable at https://doi.org/.

BiologicalX editorial field. Every article declares one of four values (robust, moderate, preliminary, insufficient) with a justification sentence, gating what claims an author can make.

See: StudyCiteThesis

Schema.org type for a page of question-answer pairs. Eligible for Google rich results with expandable Q&A cards.

US Federal Trade Commission. Regulator that requires clear and conspicuous disclosure of material connections (including affiliate relationships) between endorser and advertiser.

Glucagon-like peptide-1. Incretin hormone slowing gastric emptying and suppressing appetite. GLP-1 receptor agonists (semaglutide, tirzepatide) drive clinically significant weight loss.

See: semaglutide

DNA-methylation clock (Lu 2019) combining methylation proxies for plasma proteins and smoking pack-years. Strongest mortality predictor among the major methylation clocks.

Time for plasma drug concentration to fall by 50%. Determines dosing interval: compounds with longer half-lives accumulate across doses and reach steady state after roughly 5 half-lives.

Glycated hemoglobin. Integrates blood glucose over roughly 3 months. Used to diagnose and monitor type 2 diabetes.

Epigenetic age estimator (Horvath 2013) based on 353 CpG sites. The first widely-adopted multi-tissue methylation clock.

Hypothalamic-pituitary-adrenal axis. Stress-response system producing cortisol. Chronically elevated HPA activation drives insulin resistance, immune suppression, and hippocampal atrophy.

Hormone replacement therapy. Exogenous administration of estrogen, progesterone, or androgens for perimenopausal or hypogonadal symptoms.

Heart rate variability. Beat-to-beat interval variation. Higher HRV is associated with parasympathetic dominance and recovery readiness; commonly surfaced by Oura, Whoop, and similar wearables.

Intramuscular injection. Route of administration into muscle tissue; slower absorption than subcutaneous for some peptides.

Class of gut hormones (GLP-1, GIP) that enhance glucose-dependent insulin release. Incretin-based therapies include semaglutide, tirzepatide, and dulaglutide.

Low-density lipoprotein cholesterol. Cholesterol carried on LDL particles. Conventional lipid marker; increasingly replaced by ApoB as the primary atherosclerotic risk metric.

See: ApoB

Lipoprotein(a). Genetically determined atherogenic particle. Elevated Lp(a) roughly doubles lifetime cardiovascular risk independent of LDL. Test once in a lifetime.

Major adverse cardiovascular events. Composite endpoint in cardiovascular trials typically covering CV death, non-fatal MI, and non-fatal stroke.

Observational study design using genetic variants as instrumental variables to infer causal effects of modifiable exposures. Key method for establishing Lp(a) causality.

Metabolic equivalent of task. 1 MET = resting oxygen uptake (~3.5 mL O2 per kg per minute). Cardiorespiratory fitness is strongly graded against METs achievable on treadmill testing.

Mechanistic target of rapamycin. Nutrient-sensing kinase. mTORC1 promotes anabolic growth; mTORC1 inhibition extends lifespan in multiple model organisms.

See: rapamycin

Nicotinamide adenine dinucleotide. Coenzyme central to redox reactions and substrate for sirtuins + PARPs. NAD+ levels decline with age; supplementation with NR or NMN raises tissue levels.

ClinicalTrials.gov identifier. Format: NCT followed by 8 digits. Canonical registry link for interventional and observational trials.

Generation of new neurons from neural stem cells. Persists in adult mammals primarily in the hippocampus and is upregulated by aerobic exercise, environmental enrichment, and BDNF signalling. Implicated in learning, memory, and mood regulation.

See: BDNF

Substance with cognitive-enhancing properties. Evidence is heterogeneous; caffeine and L-theanine are among the best-supported.

See: creatine-monohydrate

Oral glucose tolerance test. 75 g glucose challenge with serial glucose + insulin measurements. Gold-standard for dysglycemia and insulin resistance assessment.

Levine 2018 biological-age estimator combining 9 blood markers (albumin, creatinine, glucose, CRP, lymphocyte percent, MCV, RDW, ALP, WBC) plus chronological age. Used by our /tools/biological-age/ calculator.

See: DNAmAge

PubChem Compound Identifier. Numeric ID for a chemical substance in the NIH PubChem database. Canonical structure lookup link.

Mixing lyophilized (freeze-dried) peptide powder with bacteriostatic water to create an injectable solution. Vial size / BAC water volume / dose determine syringe units per injection.

See: BAC water

BiologicalX editorial frontmatter field. Date an article was last re-read against current literature. Articles past 180 days are flagged at /research-index/ and visibly on the article header.

See: evidenceTier

Selective androgen receptor modulator. Tissue-selective compounds targeting androgen receptors with the goal of muscle/bone anabolism without the broader androgen profile. None FDA-approved as of 2026; HPTA suppression is typical.

Subcutaneous injection. Route of administration into fat layer under the skin; preferred for most peptides (shorter needle, less painful, similar bioavailability to IM for water-soluble molecules).

Schema.org subtype flagging DOM segments for voice assistants and AI Overviews to extract as the authoritative summary. BiologicalX points it at H1 + TL;DR callout + thesis on every article.

BiologicalX MDX component for inline study citation. Reference resolves against src/data/studies.ts; build fails if the registry key is unknown. Every article is gated to at least two StudyCite calls.

Total daily energy expenditure. Resting metabolic rate multiplied by an activity factor. Baseline for macronutrient planning; our /tools/macro-calculator/ uses Mifflin-St Jeor.

BiologicalX editorial frontmatter field. Required single-sentence claim (<= 200 chars) every article stands behind. Rendered under the H1.

See: evidenceTier

Too long; didn't read. Short summary block required at the top of every BiologicalX article via Callout component; also flagged in SpeakableSpecification for AI extraction.

Maximum oxygen consumption during progressive exercise. Strongest single cardiorespiratory fitness metric and among the best predictors of all-cause mortality. Estimated by Cooper, Rockport, and Uth-Sorensen protocols.

World Anti-Doping Agency. Body maintaining the Prohibited List for competitive athletes. Certain peptides (including BPC-157) are banned for WADA-tested athletes.

See: bpc-157

Period of no administration between compound cycles. Allows receptor resensitization or clearance of active metabolites. Length is typically 5x the elimination half-life.

See: CycleHalf-life

Wikidata entity identifier (Q\d+). Cross-lingual knowledge-graph anchor used by LLMs and Google Knowledge Graph. BiologicalX grounds compounds to Wikidata for LLM entity resolution.