Glossary

Glossary

Plain-language definitions for scientific and technical terms used on this site.

A

• ACE — Angiotensin-converting enzyme — an enzyme that raises blood pressure. ACE inhibitors are common blood pressure medications.
• ADH — Antidiuretic hormone — tells your kidneys to retain water. Alcohol suppresses ADH, which is why it increases urination.
• ADP — Adenosine diphosphate — the ‘spent’ form of ATP after your cells use energy. Creatine helps recycle ADP back into ATP.
• AI — Adequate Intake — the recommended daily intake level used when not enough data exists to set a formal RDA.
• ATP — Adenosine triphosphate — the molecule your cells burn as fuel for muscle contraction, brain activity, and nearly everything else.

B

• B12 — Vitamin B12 (cobalamin) — essential for nerve function and red blood cell production. Found almost exclusively in animal foods.
• B2 — Vitamin B2 (riboflavin) — helps convert food into energy. Found in dairy, eggs, and meat.
• BCAA — Branched-chain amino acids — leucine, isoleucine, and valine. Three essential amino acids involved in muscle building. Whole protein sources already contain them.
• BDNF — Brain-derived neurotrophic factor — a protein that helps brain cells grow, survive, and form new connections. Exercise and sleep increase BDNF.
• BMI — Body mass index — weight divided by height squared. A rough screening tool, but does not distinguish muscle from fat.
• BV — Biological value — a measure of how efficiently your body uses a protein source. Higher BV means more protein retained, less excreted.

C

• CCK — Cholecystokinin — a gut hormone released when you eat fat and protein. Signals your brain to feel full.
• CEE — Creatine ethyl ester — an alternative form of creatine marketed as better-absorbed. Studies show it is actually less effective than standard creatine monohydrate.
• CRP — C-reactive protein — a blood marker that rises with inflammation. Used to assess infection risk and chronic inflammatory status.

D

• D2 — Vitamin D2 (ergocalciferol) — the plant-derived form of vitamin D. Less effective at raising blood levels than D3.
• D3 — Vitamin D3 (cholecalciferol) — the form of vitamin D your skin makes from sunlight. More effective than D2 at raising blood levels.
• DHT — Dihydrotestosterone — a potent form of testosterone involved in hair loss (male pattern baldness) and prostate growth.
• DIAAS — Digestible Indispensable Amino Acid Score — the newer, more accurate measure of protein quality. Replaced PDCAAS as the FAO-recommended standard.
• DNA — Deoxyribonucleic acid — the molecule inside every cell that carries your genetic instructions.

E

• E535 — Sodium ferrocyanide — an anti-caking agent added to table salt to prevent clumping.
• E536 — Potassium ferrocyanide — an anti-caking agent used in salt, similar to E535.
• EAA — Essential amino acids — the 9 amino acids your body cannot make. You must get them from food. All 9 must be present to build muscle protein.

F

• FAO — Food and Agriculture Organization — a United Nations agency that sets international nutrition and food safety standards.
• FOS — Fructooligosaccharides — a type of prebiotic fiber that feeds beneficial gut bacteria. Found in onions, garlic, and bananas.

G

• GABA — Gamma-aminobutyric acid — the brain’s main calming neurotransmitter. Reduces nerve activity and promotes relaxation.
• GI — Glycemic index — a 0–100 scale ranking how quickly a food raises blood sugar. Lower GI means a slower, more gradual rise.
• GLP-1 — Glucagon-like peptide-1 — a gut hormone that reduces appetite, slows stomach emptying, and helps regulate blood sugar.
• GOS — Galactooligosaccharides — prebiotic fiber found naturally in breast milk and legumes. Feeds beneficial gut bacteria, particularly bifidobacteria.

H

• HIIT — High-intensity interval training — short bursts of intense exercise alternated with rest periods.
• HR — Heart rate — the number of times your heart beats per minute. Used to gauge exercise intensity.

I

• IBD — Inflammatory bowel disease — chronic conditions (Crohn’s disease, ulcerative colitis) involving inflammation of the digestive tract.
• IBS — Irritable bowel syndrome — a common functional gut disorder causing pain, bloating, and altered bowel habits without structural damage.
• ICD-10 — International Classification of Diseases, 10th revision — the global standard system for coding medical diagnoses.
• IL-6 — Interleukin-6 — a signaling molecule involved in inflammation and immune response. Elevated chronically in disease, but also released transiently by exercise.
• IU — International Unit — a standardized measurement for vitamins and biologically active substances. The amount per IU varies by substance.

J

• JAMA — Journal of the American Medical Association — one of the most respected peer-reviewed medical journals.

K

• K1 — Vitamin K1 (phylloquinone) — found in green leafy vegetables. Primarily involved in blood clotting.
• K2 — Vitamin K2 (menaquinone) — found in fermented foods and animal products. Directs calcium into bones and teeth rather than arteries.

L

• LDL — Low-density lipoprotein — often called ‘bad cholesterol.’ Carries cholesterol to arteries, where excess can build up as plaque.
• LPS — Lipopolysaccharide — a bacterial toxin that triggers a strong inflammatory response when it leaks from the gut into the bloodstream.

M

• MK-4 — Menaquinone-4 — a short-acting form of vitamin K2 found in animal products. Clears from the body within hours.
• MK-7 — Menaquinone-7 — a long-acting form of vitamin K2 found in fermented foods (especially natto). Stays active in the body for days.
• MMC — Migrating motor complex — the wave of gut contractions that sweeps through your intestines between meals, clearing debris and bacteria.
• MPB — Muscle protein breakdown — the ongoing process of breaking down muscle protein. Growth happens when synthesis (MPS) exceeds breakdown.
• MPS — Muscle protein synthesis — the process of building new muscle protein. Triggered by resistance exercise and adequate protein (especially leucine).
• mTORC1 — Mechanistic target of rapamycin complex 1 — the cell’s main growth switch. Activated by leucine and resistance exercise to trigger muscle protein synthesis.

N

• N3 — Omega-3 fatty acids — essential fats found in fish, flaxseed, and algae. Include EPA and DHA, which support heart and brain health.
• NAC — N-acetylcysteine — a supplement form of the amino acid cysteine. Helps the body produce glutathione, its main internal antioxidant.
• NF-kB — Nuclear factor kappa-B — a protein complex that acts as a master switch for activating inflammation genes.
• NHANES — National Health and Nutrition Examination Survey — a large, ongoing U.S. population study that tracks diet, health, and nutritional status.
• NMDA — N-methyl-D-aspartate receptor — a type of brain receptor involved in learning, memory, and sleep regulation. Glycine is a co-activator.
• NPU — Net protein utilization — the proportion of protein eaten that the body actually retains and uses.
• NREM — Non-rapid eye movement sleep — sleep stages focused on physical restoration and deep recovery. Alternates with REM sleep throughout the night.
• NSAID — Non-steroidal anti-inflammatory drug — common pain relievers like ibuprofen and aspirin. Can irritate the gut lining with chronic use.
• NSF — NSF International — an independent organization that tests and certifies supplements for safety, purity, and label accuracy.

O

• OH — Hydroxyl group — in vitamin D context, 25(OH)D is the blood test used to measure your vitamin D status.

P

• PDCAAS — Protein Digestibility-Corrected Amino Acid Score — the older standard for measuring protein quality. Being replaced by the more accurate DIAAS.
• PED — Performance-enhancing drug — substances used to improve athletic performance, often banned in competitive sports.
• PYY — Peptide YY — a gut hormone released after eating that signals fullness and slows digestion. Higher-protein meals trigger more PYY.

R

• RBC — Red blood cell — cells that carry oxygen from your lungs to the rest of your body using hemoglobin.
• RDA — Recommended Dietary Allowance — the daily intake level considered sufficient to meet the needs of most (97–98%) healthy people.
• REM — Rapid eye movement sleep — a sleep stage associated with dreaming, memory consolidation, and emotional processing.
• RNA — Ribonucleic acid — carries genetic instructions from DNA and helps build proteins.
• ROI — Return on investment — a measure of how much benefit you get relative to the cost or effort.
• RPE — Rating of perceived exertion — a subjective scale (typically 1–10) for rating how hard exercise feels.
• RS3 — Resistant starch type 3 — starch that forms when cooked starchy foods are cooled (like rice or potatoes). Acts as prebiotic fiber for gut bacteria.
• RT — Resistance training — exercise using weights or resistance to build strength and muscle.

S

• SCFA — Short-chain fatty acids — produced when gut bacteria ferment fiber. Include butyrate, propionate, and acetate. Fuel colon cells and regulate immunity.
• SIBO — Small intestinal bacterial overgrowth — bacteria proliferating in the wrong part of the intestine, causing bloating, pain, and malabsorption.
• SLC6A8 — The gene encoding the creatine transporter protein. Determines how efficiently your cells absorb creatine from the bloodstream.
• SPF — Sun protection factor — measures how well sunscreen blocks UV-B radiation. SPF 30 blocks about 97% of UV-B rays.

T

• TBI — Traumatic brain injury — damage to the brain from an external force. Creatine is being studied as a potential neuroprotective agent after TBI.
• TRE — Time-restricted eating — limiting food intake to a specific window each day (e.g., 8 hours). A form of intermittent fasting.

U

• UV — Ultraviolet radiation — invisible light from the sun. Includes UV-A (aging) and UV-B (burning and vitamin D production).
• UV-B — Ultraviolet B — the specific wavelength of sunlight that triggers vitamin D production in your skin. Blocked by sunscreen, clothing, and glass.

V

• VDR — Vitamin D receptor — a protein inside cells that binds active vitamin D and activates specific genes. Found in nearly every tissue.

W

• WHO — World Health Organization — the United Nations agency that coordinates international public health and sets global health guidelines.

Z

• ZO-1 — Zonula occludens-1 — a protein that seals the junctions between gut lining cells. When ZO-1 is disrupted, gut permeability increases (‘leaky gut’).

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Terms are auto-generated from the site term registry. Research methodology terms (RCT, meta-analysis, Grade A/B/C) are on the research page.