| Calories per gram of fat | 9 calories (USDA Dietary Reference Intakes) |
| Calories per gram of carbohydrate or protein | 4 calories each (USDA Dietary Reference Intakes) |
| General daily sodium limit (adults) | 2,300 mg (2020–2025 Dietary Guidelines for Americans) |
| General daily fiber recommendation (adults) | 25–38 g (National Academies of Medicine; varies by age and sex) |
| High %DV threshold on a nutrition label | 20% or more (FDA nutrition label guidelines) |
| Low %DV threshold on a nutrition label | 5% or less (FDA nutrition label guidelines) |
Why Nutrition Terms Matter
Nutrition labels, health headlines, and even conversations with your doctor are full of terms that can feel overwhelming — especially when no one ever defined them for you. Words like antioxidant, glycemic index, or complete protein carry real meaning that affects everyday food choices.
This glossary gives you plain-English definitions for the terms you encounter most often. No advanced science background required. Think of it as a quick reference you can return to whenever something on a label or in an article stops you short.
For a deeper dive into how these concepts fit together in a full eating plan, see our comprehensive nutrition guide. And once you're comfortable with the vocabulary, reading a nutrition label becomes much more straightforward.
Macronutrients
The three main nutrients your body needs in large amounts: carbohydrates, protein, and fat. Each provides energy (measured in calories) and plays distinct roles in bodily function.
Micronutrients
Vitamins and minerals your body requires in smaller quantities but cannot produce in sufficient amounts on its own. Examples include iron, calcium, vitamin C, and vitamin D. See our micronutrient quick-reference guide for specifics.
Antioxidant
A compound — found in many fruits, vegetables, and other plant foods — that helps protect cells from damage caused by unstable molecules called free radicals. Common antioxidants include vitamins C and E and beta-carotene.
Glycemic Index (GI)
A scale from 0 to 100 that ranks carbohydrate-containing foods by how quickly they raise blood sugar after eating. Foods with a lower GI generally cause a slower, steadier rise in blood sugar than high-GI foods.
Dietary Fiber
A type of carbohydrate found in plant foods that the body cannot fully digest. Fiber supports digestive health, helps you feel full, and is linked to a lower risk of several chronic conditions. It comes in two forms: soluble (dissolves in water) and insoluble.
Complete Protein
A protein source that contains all nine essential amino acids — the building blocks your body cannot make on its own. Animal products like eggs, meat, and dairy are complete proteins; most plant sources are not, though combinations like rice and beans together can cover all nine.
Saturated Fat
A type of fat that is solid at room temperature, found mainly in animal products and some tropical oils. Most dietary guidelines recommend limiting saturated fat intake, as high consumption is associated with elevated LDL ('bad') cholesterol levels.
Sodium
A mineral and electrolyte — familiar as the main component of table salt — that helps regulate fluid balance and nerve function. Consuming too much sodium over time is associated with elevated blood pressure in some individuals.
Added Sugars
Sugars and syrups added to foods during processing or preparation, as distinct from sugars that occur naturally in fruit or dairy. Examples include high-fructose corn syrup, cane sugar, and honey used as an ingredient.
Daily Value (%DV)
A reference percentage shown on U.S. nutrition labels indicating how much of a nutrient one serving of a food contributes toward a general daily target. A %DV of 5% or less is considered low; 20% or more is considered high.
Phytonutrients
Naturally occurring compounds in plants — including pigments like lycopene and flavonoids — that may support health, though research into many of them is still ongoing. Eating a variety of colorful plant foods is the most practical way to obtain a broad range of phytonutrients.
Omega-3 Fatty Acids
A category of polyunsaturated fats found in fatty fish, walnuts, flaxseeds, and chia seeds. They are considered essential because the body cannot produce them in adequate amounts and must obtain them through food.
Key Numbers and Measurements Explained
Beyond individual terms, nutrition information is full of numbers — percentages, grams, index scores — that require a bit of context to interpret. Here are the most important ones at a glance.
| Calories per gram of fat | 9 calories (USDA Dietary Reference Intakes) |
| Calories per gram of carbohydrate or protein | 4 calories each (USDA Dietary Reference Intakes) |
| General daily sodium limit (adults) | 2,300 mg (2020–2025 Dietary Guidelines for Americans) |
| General daily fiber recommendation (adults) | 25–38 g (National Academies of Medicine; varies by age and sex) |
| High %DV threshold on a nutrition label | 20% or more (FDA nutrition label guidelines) |
| Low %DV threshold on a nutrition label | 5% or less (FDA nutrition label guidelines) |
Understanding these values helps you make sense of both packaged food labels and general dietary guidance. Keep in mind that recommended amounts can vary by age, sex, and health status, so treat these figures as general orientation rather than personal targets. A registered dietitian can help you interpret what these numbers mean for your specific situation.
Once you're comfortable with these benchmarks, a weekly grocery checklist can help you put the numbers into practice at the store. For a broader strategy on eating nutrient-rich foods affordably, explore our guide on affordable eating.
This article is for informational purposes only and is not a substitute for personalized medical or dietary advice. Consult a qualified healthcare professional or registered dietitian for guidance specific to your health needs.