Nutrition Glossary
Definitions of key nutrition and dietary terms.
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Calorie
A unit of energy.
Macronutrient
Nutrients required in large amounts: protein, carbohydrates, and fat.
Micronutrient
Vitamins and minerals needed in small amounts but essential for proper body function.
Glycemic Index (GI)
A scale from 0-100 ranking how quickly a food raises blood sugar.
Cholesterol
A waxy substance found in animal-based foods and produced by the liver.
Antioxidant
A compound that protects cells from damage by free radicals (unstable molecules from metabolism and environmental toxins).
Metabolism
All chemical reactions in the body that convert food into energy and build/repair tissues.
Daily Value (DV)
The recommended daily intake of a nutrient based on a 2,000-calorie diet, shown as a percentage on Nutrition Facts labels.
Serving Size
A standardized amount of food used for nutrition labeling.
Whole Grain
A grain that retains all three parts: bran (fiber, B vitamins), germ (nutrients, healthy fats), and endosperm (starch, protein).
Superfood
A marketing term (not a scientific classification) for nutrient-dense foods thought to offer exceptional health benefits.
Nutrient Absorption
The process by which digested nutrients pass through the intestinal wall into the bloodstream.
RDA (Recommended Dietary Allowance)
The average daily intake level sufficient to meet the nutrient requirements of nearly all (97-98%) healthy individuals.
Tolerable Upper Intake Level (UL)
The maximum daily intake of a nutrient unlikely to cause adverse health effects in most people.
Food Allergen
A protein in food that triggers an immune response in sensitive individuals.
Organic Food
Food produced without synthetic pesticides, fertilizers, GMOs, or antibiotics.
Protein
A macronutrient made of amino acids, essential for building and repairing muscle, organs, and tissues.
Carbohydrate
A macronutrient and the body's primary energy source.
Fat
A macronutrient essential for hormone production, nutrient absorption, and cell structure.
Fiber
A type of carbohydrate the body cannot fully digest.
Saturated Fat
A type of fat with no double bonds in its fatty acid chains.
Trans Fat
An unsaturated fat with a trans configuration.
Omega-3 Fatty Acids
Essential polyunsaturated fats (ALA, EPA, DHA) that reduce inflammation, support brain health, and lower heart disease risk.
Amino Acid
The building blocks of protein.
Unsaturated Fat
A fat with one or more double bonds in its fatty acid chain.
Monounsaturated Fat (MUFA)
A fat with exactly one double bond in its fatty acid chain.
Polyunsaturated Fat (PUFA)
A fat with two or more double bonds in its fatty acid chain.
Complete Protein
A food source containing all 9 essential amino acids in adequate amounts.
Incomplete Protein
A protein source that lacks one or more of the 9 essential amino acids.
Net Carbs
The digestible carbohydrates that impact blood sugar, calculated as total carbohydrates minus dietary fiber (and sometimes sugar alcohols).
Vitamin
An organic compound needed in small amounts for normal metabolism.
Vitamin A
A fat-soluble vitamin essential for vision, immune function, and skin health.
Vitamin B1 (Thiamine)
A water-soluble B vitamin essential for converting carbohydrates into energy and nerve function.
Vitamin B2 (Riboflavin)
A water-soluble vitamin involved in energy metabolism (converting food to ATP) and antioxidant activity.
Vitamin B3 (Niacin)
A water-soluble vitamin that supports energy metabolism, DNA repair, and skin health.
Vitamin B5 (Pantothenic Acid)
A water-soluble vitamin required for synthesizing coenzyme A (CoA), which is central to energy metabolism and fatty acid synthesis.
Vitamin B6 (Pyridoxine)
A water-soluble vitamin essential for protein metabolism, neurotransmitter synthesis, and immune function.
Vitamin B7 (Biotin)
A water-soluble vitamin essential for fatty acid synthesis, amino acid metabolism, and glucose production.
Vitamin B9 (Folate / Folic Acid)
A water-soluble vitamin critical for DNA synthesis and cell division.
Vitamin B12 (Cobalamin)
A water-soluble vitamin essential for nerve function, red blood cell formation, and DNA synthesis.
Vitamin C (Ascorbic Acid)
A water-soluble antioxidant vitamin essential for collagen synthesis, immune function, and iron absorption.
Vitamin D
A fat-soluble vitamin (also a hormone) essential for calcium absorption and bone health.
Vitamin E (Tocopherol)
A fat-soluble antioxidant vitamin that protects cell membranes from oxidative damage.
Vitamin K
A fat-soluble vitamin essential for blood clotting (K1) and bone metabolism (K2).
Mineral
An inorganic nutrient needed for body functions like bone formation, fluid balance, and nerve signaling.
Sodium
An essential mineral that regulates fluid balance, nerve function, and blood pressure.
Potassium
A mineral and electrolyte crucial for heart function, muscle contraction, and fluid balance.
Calcium
The most abundant mineral in the body, essential for bone and teeth health, muscle function, and blood clotting.
Iron
A mineral essential for hemoglobin (oxygen transport in blood) and myoglobin (oxygen storage in muscle).
Electrolyte
Minerals that carry an electric charge in body fluids.
Magnesium
A mineral involved in over 300 enzymatic reactions, including energy production, protein synthesis, and muscle/nerve function.
Zinc
A trace mineral essential for immune function, wound healing, DNA synthesis, and taste/smell perception.
Phosphorus
The second most abundant mineral in the body, essential for bone structure (as hydroxyapatite with calcium), energy (ATP), and cell membranes (phospholipids).
Selenium
A trace mineral and antioxidant component of selenoproteins, essential for thyroid hormone metabolism and immune function.
Iodine
A trace mineral essential for thyroid hormone synthesis, which regulates metabolism and growth.
Copper
A trace mineral serving as a cofactor for enzymes involved in iron metabolism, antioxidant defense, and connective tissue formation.
Manganese
A trace mineral that activates enzymes for bone formation, metabolism of carbohydrates, amino acids, and cholesterol, and antioxidant activity.
Chromium
A trace mineral that enhances the action of insulin and is involved in macronutrient metabolism.
Fluoride
A trace mineral essential for tooth enamel strength and cavity prevention.
Molybdenum
A trace mineral that acts as a cofactor for enzymes that break down sulfur-containing amino acids and certain toxins.
Leucine
The most anabolic of the branched-chain amino acids (BCAAs), leucine directly activates the mTOR pathway to stimulate muscle protein synthesis.
Isoleucine
A branched-chain essential amino acid that supports muscle metabolism, immune function, and hemoglobin production.
Valine
One of three branched-chain amino acids (BCAAs).
BCAA (Branched-Chain Amino Acids)
The three essential amino acids — leucine, isoleucine, and valine — with aliphatic side chains.
Lysine
An essential amino acid critical for collagen synthesis, calcium absorption, and antiviral immune function.
Methionine
An essential sulfur-containing amino acid that initiates protein synthesis and serves as a precursor for cysteine, taurine, and the antioxidant glutathione.
Tryptophan
An essential amino acid and precursor to serotonin (mood) and melatonin (sleep).
Histidine
An essential amino acid (especially critical during childhood) that is a precursor to histamine, carnosine, and anserine.
Threonine
An essential amino acid required for the biosynthesis of glycine and serine, important for collagen and elastin production and immune function.
Phenylalanine
An essential amino acid and precursor to tyrosine, dopamine, epinephrine, and norepinephrine (neurotransmitters).
EPA (Eicosapentaenoic Acid)
A long-chain omega-3 fatty acid with 20 carbons.
DHA (Docosahexaenoic Acid)
A long-chain omega-3 fatty acid with 22 carbons, critical for brain and eye development and function.
ALA (Alpha-Linolenic Acid)
The plant-based essential omega-3 fatty acid (18 carbons).
CLA (Conjugated Linoleic Acid)
A naturally occurring trans fatty acid found in meat and dairy from ruminants, associated with potential body composition and immune benefits.
MCT (Medium-Chain Triglycerides)
Fats with 6-12 carbon chains that are absorbed directly into the portal vein (bypassing lymphatic digestion), rapidly converted to ketones by the liver, and used as quick energy.
Oleic Acid
The most common monounsaturated fatty acid (omega-9), making up ~73% of olive oil.
Linoleic Acid
The most common dietary omega-6 polyunsaturated fatty acid, essential (cannot be synthesized by the body).
Arachidonic Acid
An omega-6 polyunsaturated fatty acid synthesized from linoleic acid.
Glucose
The body's primary fuel molecule, a simple sugar (monosaccharide).
Fructose
A naturally occurring simple sugar in fruits and honey.
Sucrose
Common table sugar, a disaccharide made of glucose + fructose.
Lactose
The sugar naturally found in milk and dairy products, a disaccharide made of glucose + galactose.
Maltose
A disaccharide made of two glucose molecules, produced when starch breaks down during digestion or fermentation.
Galactose
A monosaccharide that pairs with glucose to form lactose.
High-Fructose Corn Syrup (HFCS)
A sweetener made by converting corn starch glucose to fructose.
Sugar Alcohol
A carbohydrate that provides fewer calories (1.5-3 kcal/g vs 4 kcal/g for sugar), does not spike blood sugar significantly, and does not cause tooth decay.
Ketosis
A metabolic state where the liver converts fat into ketone bodies (acetoacetate, beta-hydroxybutyrate) used as fuel when carbohydrate intake is very low (typically <50g/day).
Calorie Deficit
Consuming fewer calories than the body expends (TDEE), resulting in weight loss.
Calorie Surplus
Consuming more calories than the body expends (TDEE), resulting in weight gain.
Intermittent Fasting
An eating pattern that cycles between periods of fasting and eating.
Carb Cycling
A dietary strategy that alternates between high and low carbohydrate days, typically matching higher carb intake to intense training days.
Reverse Dieting
A strategy of gradually increasing calorie intake after a caloric restriction period to restore metabolic rate and hormonal function without significant fat regain.
Metabolic Adaptation
The body's physiological response to caloric restriction: reduced TDEE through lower BMR, reduced NEAT, and hormonal changes (lower leptin, higher ghrelin).
Refeeding
A planned period of increased calorie and carbohydrate intake during a caloric restriction diet.
Bioavailability
The proportion of an ingested nutrient that is absorbed and utilized by the body.
Nutrient Density
The ratio of beneficial nutrients to total calories in a food.
Thermic Effect of Food (TEF)
The energy required to digest, absorb, and metabolize nutrients.
Food Fortification
The deliberate addition of essential nutrients to food to prevent deficiencies in a population.
Hydrogenation
An industrial process adding hydrogen to unsaturated fats to make them more solid and stable.
Pasteurization
Heat treatment to kill or inactivate pathogens and spoilage organisms in food and beverages without significantly altering nutritional content or flavor.
Glycemic Load (GL)
A measure combining glycemic index and carbohydrate quantity: GL = (GI × carb grams) / 100.
Phytochemical
Bioactive compounds produced by plants (not essential nutrients) that may offer health benefits.
Probiotics
Live microorganisms (mainly bacteria and yeast) that provide health benefits, especially for gut health.
Prebiotics
Non-digestible food components (mainly fibers and oligosaccharides) that selectively feed beneficial gut bacteria.
Synbiotics
Products or dietary approaches that combine probiotics and prebiotics synergistically.
Gut Microbiome
The complex community of trillions of microorganisms (bacteria, archaea, fungi, viruses) living in the gastrointestinal tract.
Fermentation
A metabolic process where microorganisms (bacteria, yeast, molds) break down carbohydrates producing organic acids, gases, or alcohol.
Digestive Enzymes
Proteins that catalyze the breakdown of macronutrients: amylase (carbs), protease (protein), lipase (fat), and lactase (lactose).
Leaky Gut (Intestinal Permeability)
A condition where tight junctions in the intestinal lining become loose, allowing bacteria and toxins to pass into the bloodstream.
FODMAP
Fermentable Oligosaccharides, Disaccharides, Monosaccharides And Polyols — short-chain carbs poorly absorbed in the small intestine.
BMR (Basal Metabolic Rate)
The number of calories your body burns at rest to maintain vital functions like breathing, circulation, and cell production.
TDEE (Total Daily Energy Expenditure)
The total number of calories you burn per day, including BMR, physical activity, and the thermic effect of food.
BMI (Body Mass Index)
A screening tool calculated as weight(kg) / height(m)^2.
Body Fat Percentage
The proportion of total body mass composed of fat.
Lean Body Mass (LBM)
Total body weight minus fat mass, including muscle, bone, organs, and water.
Resting Metabolic Rate (RMR)
The calories burned at rest, similar to BMR but measured under less strict conditions (no overnight fast required).
Waist-to-Hip Ratio (WHR)
Waist circumference divided by hip circumference.
Visceral Fat
Fat stored within the abdominal cavity around internal organs (liver, pancreas, intestines).
Subcutaneous Fat
Fat stored just beneath the skin.
Stevia
A natural, non-caloric sweetener derived from the leaves of Stevia rebaudiana.
Aspartame
An artificial sweetener ~200x sweeter than sucrose, providing 4 kcal/g but used in such tiny amounts it's effectively calorie-free.
Sucralose
A chlorinated artificial sweetener ~600x sweeter than sucrose.
Erythritol
A sugar alcohol with 0.24 kcal/g (6% of sucrose's calories), GI of 0, and 70% of sucrose's sweetness.
Xylitol
A sugar alcohol with 2.4 kcal/g and GI of ~7, equal sweetness to sucrose.
Monk Fruit (Luo Han Guo)
A natural zero-calorie sweetener derived from a small melon native to southern China.
Acesulfame-K (Ace-K)
An artificial sweetener ~200x sweeter than sucrose, zero calories, heat-stable, with a slightly bitter aftertaste often masked by blending with other sweeteners.
Saccharin
The oldest artificial sweetener (discovered 1879), ~300-400x sweeter than sucrose, zero calories.
Inflammation
The immune system's protective response to injury or infection.
Oxidative Stress
An imbalance between free radical production and the body's antioxidant defenses.
Insulin Resistance
A condition where cells fail to respond normally to insulin, requiring the pancreas to produce more insulin to maintain blood sugar.
Metabolic Syndrome
A cluster of conditions occurring together — high blood pressure, high blood sugar, excess waist fat, abnormal cholesterol/triglycerides — that increase risk of heart disease, stroke, and diabetes.
Hypertension
Chronically elevated blood pressure (≥130/80 mmHg per 2017 ACC/AHA guidelines).
Anemia
A condition with insufficient healthy red blood cells to carry adequate oxygen.
Osteoporosis
A disease characterized by low bone density and deteriorated bone structure, increasing fracture risk.