Understand nutrition terminology with our comprehensive glossary of 49 essential terms. From calories to probiotics, learn the language of nutrition science.
The building blocks of proteins, consisting of 20 different types that combine in various sequences to form thousands of different proteins in your body. Nine are "essential" amino acids that must come from food because your body cannot produce them. Complete proteins contain all essential amino acids, while incomplete proteins lack one or more.
Compounds that protect cells from damage caused by free radicals, unstable molecules produced during normal metabolism and from environmental factors. Common antioxidants include vitamins C and E, beta-carotene, and selenium. Foods rich in antioxidants include berries, dark chocolate, pecans, and artichokes. A diet high in antioxidants may reduce chronic disease risk.
A group of eight water-soluble vitamins (B1, B2, B3, B5, B6, B7, B9, B12) essential for energy metabolism, nervous system function, and red blood cell production. Each B vitamin has unique functions: B12 supports nerve health, B9 (folate) is crucial during pregnancy, and B6 aids protein metabolism. Found in whole grains, meats, eggs, and leafy greens.
The number of calories your body burns at complete rest to maintain vital functions like breathing, circulation, and cell production. BMR accounts for 60-75% of daily calorie expenditure and is influenced by age, sex, weight, height, and genetics. Muscle mass increases BMR, which is why strength training can help with weight management.
The most abundant mineral in your body, essential for building and maintaining strong bones and teeth. Calcium also plays crucial roles in muscle function, nerve transmission, and blood clotting. Dairy products are rich sources, but calcium is also found in fortified plant milks, leafy greens, and sardines. Adults need 1,000-1,200 mg daily.
A state where you consume fewer calories than your body burns, forcing it to use stored energy (primarily fat) to make up the difference. A deficit of 500 calories per day typically results in about one pound of weight loss per week. Creating a moderate, sustainable caloric deficit through diet and exercise is the foundation of healthy weight loss.
A state where you consume more calories than your body burns, providing excess energy for tissue growth. Athletes and bodybuilders intentionally create a surplus to build muscle mass. A moderate surplus of 250-500 calories daily, combined with resistance training, supports muscle growth while minimizing fat gain.
A unit of energy measurement in food. Technically, a calorie is the amount of energy needed to raise one gram of water by one degree Celsius. In nutrition, we typically use kilocalories (kcal), where 1 kilocalorie equals 1,000 calories. Your body burns calories to fuel everything from basic cellular functions to intense physical activity. The number of calories you need daily depends on your age, sex, weight, and activity level.
Your body's primary and preferred source of energy, providing 4 calories per gram. Carbohydrates include sugars, starches, and fiber. They're found in grains, fruits, vegetables, and dairy. Simple carbs provide quick energy while complex carbs offer sustained fuel. Your brain alone requires about 120 grams of glucose daily to function optimally.
A waxy, fat-like substance found in all cells of your body. Your liver produces all the cholesterol you need for hormone production, vitamin D synthesis, and bile production. Dietary cholesterol comes from animal products. While once thought to significantly impact blood cholesterol, current research suggests saturated fat intake has a greater effect on blood cholesterol levels.
A protein source containing all nine essential amino acids in adequate proportions. Animal proteins (meat, fish, eggs, dairy) are typically complete. Plant-based complete proteins include quinoa, soy, and hemp seeds. Eating a variety of plant proteins throughout the day can also provide all essential amino acids without relying on complete protein sources.
The recommended daily intake of a nutrient, expressed as a percentage on nutrition labels. DVs are based on a 2,000-calorie diet and help consumers understand how much a serving contributes to daily needs. A food with 20% DV of fiber provides 20% of your daily fiber needs per serving. DVs are general guidelines and individual needs may vary.
Minerals that carry an electric charge when dissolved in body fluids. The main electrolytes are sodium, potassium, calcium, magnesium, chloride, and phosphate. They regulate nerve and muscle function, hydration, blood pH, and tissue repair. Electrolytes are lost through sweat and need to be replenished, especially during intense exercise or illness.
Calories from foods that provide energy but minimal nutritional value in terms of vitamins, minerals, fiber, or protein. Common sources include sugary drinks, candy, chips, and alcohol. While these foods can be enjoyed occasionally, relying on them displaces more nutritious options and can contribute to weight gain and nutrient deficiencies.
Foods that have nutrients added back that were lost during processing. For example, white flour is enriched with B vitamins and iron that were removed when the grain was refined. While enrichment restores some lost nutrients, enriched products still lack the fiber and other beneficial compounds found in whole grain versions.
Fats that your body cannot produce and must be obtained from food. The two main types are omega-3 (found in fatty fish, flaxseeds, and walnuts) and omega-6 (found in vegetable oils). These fats are crucial for brain function, cell membrane integrity, and reducing inflammation. Most Western diets contain excess omega-6, making omega-3 intake especially important.
A macronutrient providing 9 calories per gram, making it the most energy-dense nutrient. Dietary fats are essential for hormone production, brain health, vitamin absorption, and cell membrane integrity. Not all fats are equal; unsaturated fats from nuts, avocados, and olive oil are considered heart-healthy, while trans fats should be avoided.
A type of carbohydrate that your body cannot digest, yet is crucial for digestive health. Fiber adds bulk to stool, feeds beneficial gut bacteria, helps control blood sugar, and promotes feelings of fullness. There are two types: soluble fiber (dissolves in water, found in oats and beans) and insoluble fiber (does not dissolve, found in whole grains and vegetables). Adults should aim for 25-38 grams daily.
Foods that have nutrients added that were not originally present or were present in insignificant amounts. Common examples include milk fortified with vitamin D, orange juice with calcium, and cereals with various vitamins and minerals. Fortification helps address nutrient deficiencies in populations and can be especially important for specific dietary needs.
A ranking system (0-100) that measures how quickly carbohydrate-containing foods raise blood sugar levels. High-GI foods (70+) cause rapid spikes, while low-GI foods (55 or less) provide steadier energy. Low-GI diets may help manage diabetes, control appetite, and improve heart health. White bread has a high GI, while most vegetables have a low GI.
The process of providing adequate water and fluids to maintain bodily functions. Water makes up about 60% of body weight and is essential for temperature regulation, nutrient transport, waste removal, and cellular function. Fluid needs vary based on activity, climate, and individual factors. General recommendations suggest 8-10 cups daily, though needs increase with exercise and heat.
A protein source that lacks one or more essential amino acids or contains them in insufficient amounts. Most plant proteins (except soy, quinoa, and hemp) are incomplete. However, combining different plant proteins, like rice and beans, provides a complete amino acid profile. This combination does not need to happen in the same meal.
A mineral essential for making hemoglobin, the protein in red blood cells that carries oxygen throughout your body. Iron also supports immune function and cognitive development. There are two types: heme iron (from animal sources, better absorbed) and non-heme iron (from plants). Iron deficiency is the most common nutritional deficiency worldwide, causing fatigue and weakness.
Often abbreviated as kcal, kilocalories are the standard unit for measuring food energy. One kilocalorie equals 1,000 small calories. When nutrition labels list "calories," they actually mean kilocalories. For example, a banana with 89 calories actually contains 89 kilocalories of energy. This measurement helps people track energy intake for weight management and dietary planning.
The three main nutrients your body needs in large quantities: protein, carbohydrates, and fats. These macros provide calories and serve essential functions. Protein builds muscle and repairs tissue, carbohydrates provide quick energy, and fats support hormone production and nutrient absorption. Balancing macronutrients is key to achieving various health and fitness goals.
The sum of all chemical processes in your body that convert food into energy and building materials. Metabolism includes catabolism (breaking down molecules for energy) and anabolism (building complex molecules). Metabolic rate varies between individuals and is influenced by age, body composition, hormones, and activity level.
Essential vitamins and minerals your body needs in smaller amounts compared to macronutrients. Despite their small quantities, micronutrients are crucial for immune function, bone health, brain function, and hundreds of biochemical processes. Deficiencies can lead to serious health problems, making a varied diet important for adequate micronutrient intake.
A loosely defined term suggesting minimal processing and no artificial ingredients, though it has no strict regulatory definition in many countries. "Natural" does not mean organic, healthy, or low in calories. Foods labeled natural may still contain high amounts of sugar, sodium, or fat. Always check nutrition labels rather than relying on "natural" claims.
A measure of how many beneficial nutrients a food provides relative to its calorie content. Nutrient-dense foods pack more vitamins, minerals, fiber, and protein per calorie. Examples include leafy greens, berries, salmon, and eggs. Choosing nutrient-dense foods helps you meet nutritional needs without excess calories.
Foods produced according to specific agricultural standards that prohibit or limit synthetic pesticides, herbicides, fertilizers, antibiotics, and growth hormones. Organic livestock must have access to the outdoors and be fed organic feed. While organic foods may have lower pesticide residues, nutritional differences compared to conventional foods are generally minimal.
Natural compounds found in plants that provide health benefits beyond basic nutrition. Also called phytochemicals, they include flavonoids, carotenoids, and polyphenols. These compounds give fruits and vegetables their vibrant colors and may reduce inflammation, support immune function, and protect against chronic diseases. Eating a colorful variety of plant foods ensures diverse phytonutrient intake.
A vital mineral and electrolyte that helps maintain fluid balance, muscle contractions, and nerve signals. Potassium also helps counteract the negative effects of sodium on blood pressure. Good sources include bananas, potatoes, spinach, and beans. Most adults should aim for 2,600-3,400 mg daily, though many fall short of this goal.
Non-digestible fibers that serve as food for beneficial gut bacteria. Unlike probiotics (which are living organisms), prebiotics are food compounds that promote the growth of healthy microorganisms already in your digestive system. Good sources include garlic, onions, bananas, oats, and asparagus. Prebiotics support digestive health and may enhance immune function.
Live beneficial bacteria and yeasts that support digestive health and immune function when consumed in adequate amounts. They help maintain a healthy balance of gut microorganisms. Natural sources include yogurt, kefir, sauerkraut, kimchi, and other fermented foods. Probiotic supplements are also available but quality varies widely.
Foods that have been altered from their natural state through methods like canning, freezing, dehydrating, or adding preservatives. Processing ranges from minimal (washed salad greens) to ultra-processed (soft drinks, chips). While some processing is harmless, ultra-processed foods often contain excess sodium, sugar, and unhealthy fats with minimal nutritional value.
A macronutrient composed of amino acids that serves as the building block for muscles, organs, hormones, and enzymes. Protein helps repair tissue, supports immune function, and provides 4 calories per gram. High-protein foods include chicken, fish, eggs, legumes, and dairy. Most adults need 0.8 to 1.2 grams of protein per kilogram of body weight daily.
The average daily intake level sufficient to meet the nutritional requirements of 97-98% of healthy individuals in a specific age and sex group. RDAs are established by expert panels based on scientific evidence. For example, the RDA for protein is 0.8 grams per kilogram of body weight for sedentary adults.
A type of fat with no double bonds between carbon atoms, making it solid at room temperature. Found primarily in animal products like butter, cheese, and fatty meats, as well as coconut and palm oils. High intake has been linked to elevated LDL cholesterol. Current guidelines recommend limiting saturated fat to less than 10% of daily calories.
A standardized amount of food used to report nutrition information, set by regulatory agencies to enable fair comparisons between products. Serving sizes are based on typical consumption amounts, not recommendations. Always check serving sizes on labels, as packages often contain multiple servings. One serving of pasta, for example, is typically 2 ounces dry.
An essential mineral and electrolyte that helps regulate fluid balance, blood pressure, and nerve function. While necessary for health, most people consume too much sodium, primarily from processed foods and restaurant meals. Excess sodium can raise blood pressure and increase heart disease risk. The recommended daily limit is 2,300 mg, though many health organizations suggest 1,500 mg for optimal health.
The total number of calories you burn in a day, including BMR plus calories burned through physical activity, digestion, and non-exercise movement. TDEE is the key number for weight management: eating fewer calories than your TDEE creates a deficit for weight loss, while eating more creates a surplus for weight gain.
Artificially created fats formed when hydrogen is added to liquid vegetable oils to make them solid (hydrogenation). Trans fats raise LDL (bad) cholesterol while lowering HDL (good) cholesterol, significantly increasing heart disease risk. Most health organizations recommend eliminating trans fats entirely from your diet. Check labels for "partially hydrogenated oils."
Heart-healthy fats that remain liquid at room temperature due to double bonds in their chemical structure. Includes monounsaturated fats (olive oil, avocados) and polyunsaturated fats (fatty fish, walnuts). These fats can help lower LDL cholesterol, reduce inflammation, and support brain health when they replace saturated and trans fats in your diet.
A fat-soluble vitamin crucial for vision, immune function, reproduction, and cell growth. It exists as preformed vitamin A (retinol, found in animal products) and provitamin A (beta-carotene, found in colorful fruits and vegetables). Beta-carotene also acts as an antioxidant. Good sources include sweet potatoes, carrots, eggs, and liver.
A water-soluble vitamin and powerful antioxidant that supports immune function, collagen production, wound healing, and iron absorption. Unlike most animals, humans cannot produce vitamin C and must obtain it from food. Citrus fruits, bell peppers, strawberries, and broccoli are excellent sources. Daily needs are 75-90 mg for adults.
Often called the "sunshine vitamin," this fat-soluble vitamin is produced by your skin when exposed to sunlight. It is essential for calcium absorption, bone health, immune function, and mood regulation. Many people are deficient, especially those living in northern latitudes. Food sources include fatty fish, egg yolks, and fortified products.
A fat-soluble antioxidant that protects cells from oxidative damage caused by free radicals. It also supports immune function, skin health, and may help prevent chronic diseases. Vitamin E is found naturally in nuts, seeds, vegetable oils, and leafy greens. Most adults need 15 mg daily, which is easily obtained through a balanced diet.
A fat-soluble vitamin essential for blood clotting and bone metabolism. There are two main forms: K1 (phylloquinone) from leafy greens and K2 (menaquinone) from fermented foods and animal products. Without adequate vitamin K, blood cannot clot properly. Leafy green vegetables like kale, spinach, and broccoli are excellent sources.
Foods that are unprocessed or minimally processed, remaining close to their natural state. Examples include fresh fruits, vegetables, whole grains, legumes, nuts, and unprocessed meats. Whole foods typically provide more fiber, vitamins, and minerals than processed alternatives, and they lack added sugars, sodium, and artificial ingredients.
Now that you understand the terminology, put your knowledge to use. Browse our database of 300,000+ foods or use our calculators to plan your nutrition.
Nutrition science can seem overwhelming with its specialized vocabulary. This glossary provides clear, accessible definitions for common nutrition terms you will encounter on food labels, in diet plans, and when researching healthy eating strategies.
Understanding nutrition terminology empowers you to make informed food choices, evaluate diet claims critically, and communicate effectively with healthcare providers about your dietary needs. Whether you are managing a health condition, pursuing fitness goals, or simply wanting to eat better, knowing these terms is essential.
Use the alphabetical navigation above to jump directly to specific letters, or scroll through to browse all definitions. Each term includes practical context and links to related foods or tools on CalorieData where applicable. Bookmark this page as a reference for your nutrition journey.