A Glossary of Nutrition Terms Worth Knowing

Macronutrients

The three major nutrient categories — carbohydrates, proteins, and fats — that provide the body with energy measured in calories. Each plays distinct structural and functional roles beyond simply supplying fuel.

Micronutrients

Vitamins and minerals required in smaller amounts than macronutrients but essential for virtually every biological process. Because the body cannot synthesize most of them in sufficient quantities, they must come from food.

Dietary Fiber

A type of carbohydrate found in plant foods that the body cannot fully digest. Soluble fiber dissolves in water and can help moderate blood glucose and cholesterol levels; insoluble fiber adds bulk to stool and supports digestive regularity.

Glycemic Index (GI)

A scale from 0 to 100 that ranks carbohydrate-containing foods by how quickly they raise blood glucose relative to pure glucose. GI is one useful lens for evaluating carbohydrate quality, but it doesn't account for portion size or the full nutritional profile of a food.

Antioxidants

Compounds — including vitamins C and E, selenium, and plant polyphenols — that help neutralize unstable molecules called free radicals. Diets rich in antioxidant-containing foods (fruits, vegetables, whole grains) are associated with reduced chronic disease risk in observational research.

Phytonutrients

Bioactive compounds produced by plants — such as flavonoids, carotenoids, and glucosinolates — that are not classified as essential nutrients but may support health. Most are consumed by eating a wide variety of colorful plant foods.

Daily Value (DV)

Reference amounts established by the FDA and used on U.S. Nutrition Facts labels to indicate how much of a nutrient one serving contributes toward a general daily intake benchmark. DVs are based on a 2,000-calorie reference diet and are intended as a comparative guide, not personalized targets.

Bioavailability

The proportion of a nutrient that is actually absorbed and used by the body after consumption. Bioavailability varies by nutrient form, food matrix, preparation method, and individual digestive factors.

Saturated Fat

A type of dietary fat in which carbon atoms are fully bonded with hydrogen atoms, making it solid at room temperature. It is found primarily in animal products and some tropical oils. U.S. dietary guidelines recommend limiting saturated fat intake based on cardiovascular risk evidence.

Omega-3 Fatty Acids

A family of polyunsaturated fats — including ALA (found in plant sources) and EPA and DHA (found in fatty fish and algae) — linked in research to heart and brain health. ALA is considered essential because the body cannot produce it.

Probiotics

Live microorganisms found in fermented foods (such as yogurt, kefir, and kimchi) or supplements that, when consumed in adequate amounts, may confer health benefits by influencing the gut microbiome. Research into their specific effects is active and evolving.

Refined Grains

Grains that have been processed to remove the bran and germ layers, resulting in a finer texture but lower fiber, vitamin, and mineral content compared to whole grains. White flour and white rice are common examples.