Common Nutrition and Diet Abbreviations

IU, RDA, DRI, g, mg...All those letters can start to look like alphabet soup. When you read articles about nutrition, diet, and nutritional supplements, you're likely to come across some abbreviations. We're here to decipher these them—and let you know what's what.

Below are some of the most common nutrition and diet-related abbreviations and their definitions (most are indicated in the 2015-2020 Dietary Guidelines, or otherwise noted).

AA—Amino acids: Simple organic components of proteins

ADEK—Vitamins A, D, E, and K: These fat-soluble vitamins are sometimes grouped together.

AI—Adequate intake: The amount of a nutrient that will meet an individual's daily requirements; it's used when a recommended dietary allowance (RDA) can't be determined.

BMI—Body mass index: A value derived from a person's body mass divided by the square of their height; this measurement is used as an indicator to determine if a person is at a healthy weight, obese, or underweight.

Ca—Calcium: A dietary mineral needed for healthy bones and teeth, normal blood clotting, and nerve and muscle function.

DRI—Dietary reference intake: The general reference values for the levels of nutrients a healthy person needs to consume per day; it includes recommended dietary allowance (RDA), adequate intake (AI), and tolerable upper intake level (UL).

EAR—Estimated average requirement: The intake level of a nutrient that will meet the requirements of one-half of healthy individuals in a particular age and sex group.

EER—Estimated energy requirements: The estimated range of calories individuals need, differing by several factors, such age, sex, height, weight, and physical activity.

Fe—Iron: A dietary mineral required for the transportation of oxygen throughout the body.

FTT—Failure to thrive: A significant delay in the growth of an infant or young child.

g—Gram: A metric unit of measure; carbohydrates, fats, and proteins are measured in grams. (Note: One ounce is about 29 grams.)

IU—International unit: A measure of the activity of vitamins and drugs; vitamins A, D, and E are often measured in this way. (Note: Conversion from IU to mg is different for each vitamin.)

K—Potassium: A dietary mineral that's needed for water balance and healthy muscle function in the body.

kcal—Kilocalorie: A measure of energy that we commonly refer to as a "calorie."

mcg—Microgram: A metric unit of measure; some vitamins and minerals are measured in micrograms. (Note: 1,000 micrograms equal one milligram.)

mg—Milligram: Another metric unit of measure; many vitamins and minerals are measured in milligrams. (Note: 1,000 milligrams equal one gram.)

Mg—Magnesium: A dietary mineral needed for healthy muscle function and other processes in the body.

mEq—Milliequivalent: A measurement that's equal to one-thousandth of a gram equivalent.

Na—Sodium: A dietary mineral that's needed for water balance in the body.

RDA—Recommended dietary allowances: ​RDA designates the amount of a nutrient that will meet the requirements of 97%-98% of healthy individuals.

REE—​Resting energy expenditure: The number of calories you would burn if you stayed at rest all day.

RN—​​Reference nutrient intake: RN is used in the UK. It stands for daily nutrient recommendations to meet the needs of the majority of the population.

UL—​Tolerable upper intake level: The highest level of a nutrient that's safe for all individuals.