Key Nutrition Terms Defined: A Plain-Language Glossary

Macronutrients

The three main nutrient categories — carbohydrates, proteins, and fats — that supply the body with energy (measured in calories). They are needed in relatively large amounts compared to micronutrients.

Micronutrients

Vitamins and minerals required by the body in smaller amounts to support functions like immunity, bone health, and energy metabolism. They do not supply calories directly.

Dietary Fiber

A type of carbohydrate found in plant foods that the body cannot fully digest. Fiber supports digestive health, helps regulate blood sugar levels, and contributes to feelings of fullness.

Antioxidants

Compounds — including certain vitamins, minerals, and plant chemicals — that help neutralize unstable molecules called free radicals. Fruits, vegetables, and whole grains are common sources.

Glycemic Index (GI)

A scale from 0 to 100 that ranks how quickly a carbohydrate-containing food raises blood glucose levels relative to pure glucose. Lower-GI foods tend to produce a slower, more gradual blood sugar response.

Saturated Fat

A type of dietary fat found primarily in animal products and some tropical oils that is solid at room temperature. Major health organizations recommend limiting saturated fat intake as part of a balanced diet.

Omega-3 Fatty Acids

A family of polyunsaturated fats found in fatty fish, flaxseeds, and walnuts. Research supports their role in heart and brain health, though individual needs and sources vary.

Bioavailability

The proportion of a nutrient that is absorbed from food and available for use by the body. Bioavailability can be influenced by cooking methods, food combinations, and individual digestive differences.

Daily Value (DV)

A reference amount established by the U.S. Food and Drug Administration (FDA) used on Nutrition Facts labels to show how much of a nutrient a serving of food contributes to a general daily diet.

Phytonutrients

Naturally occurring plant compounds — such as flavonoids, carotenoids, and polyphenols — associated with health-supporting properties. They are not classified as essential nutrients but are found abundantly in colorful fruits and vegetables.

Refined Grains

Grains that have been processed to remove the bran and germ layers, which reduces fiber and some nutrient content. White flour and white rice are common examples; they differ from whole grains, which retain those layers.

Added Sugars

Sugars and syrups added to foods during processing or preparation, distinct from naturally occurring sugars found in fruit or milk. U.S. dietary guidelines recommend limiting added sugar intake.