How to read nutrition fact labels

Learn the Real Simple definitions for 12 common nutritional terms.

Serving Size
This number is at the top for a reason: The nutritional information on the rest of the label applies to one serving. The FDA sets serving sizes for all foods―they are measurements, not recommendations. Total calories are calculated per serving, as are total calories from fat, so be sure to look at the servings per container. A bag of potato chips might say it has 150 calories per serving, but the entire bag might be three servings, or 450 calories.

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Percent of Daily Value
This is calculated for a moderately active woman, or a fairly sedentary man, who eats 2,000 calories a day. (Highly active women, moderately active men, and growing teen boys may need closer to 2,500 calories a day.) A serving of Cheerios with ½ cup of skim milk gives the average adult just 3 percent of the daily value of fat intake and 11 percent of the daily value of fiber intake recommended by the U.S. Department of Agriculture (USDA).

Fat
More important than total fat are the numbers for saturated, polyunsaturated, monounsaturated, and trans fats. You want to see that the food contains relatively little saturated fat and trans fat, and relatively more polyunsaturated and monounsaturated. Keep in mind that "fat-free" doesn't equal "calorie-free." Many fat-free and low-fat foods have added sugar.

Cholesterol
This is a fat-like chemical that's an essential component of cell membranes, a covering for nerve-cell fibers, and a building block of hormones. Only animal products contain cholesterol. Adults are advised to limit their daily intake to 300 milligrams. Too much can elevate your blood cholesterol, raising your heart-disease risk.

Sodium
The recommended daily limit for an average adult is 2,300 milligrams; too much sodium can cause high blood pressure. By the USDA's reckoning, a food is low in sodium if it contains no more than 140 milligrams. (A serving of Cheerios has 210 milligrams and is therefore not low in sodium.) A single serving of soup or a frozen dinner may contain 1,000 milligrams or more of sodium, which is nearly half the daily limit.

Potassium
Getting enough of this mineral―4,700 milligrams a day for adults―may help prevent high blood pressure. Low potassium can lead to an irregular heartbeat.

Total Carbohydrate
This large category includes everything from whole grains (healthy carbs) to sugar and other refined carbs (unhealthy ones). It's most helpful to look at the sugar and fiber numbers.

Dietary Fiber
The average adult should eat between 21 and 35 grams of fiber daily, but most don't reach that level. When buying bread or cereal, look for a brand with 3 grams or more per serving. Some labels describe whether the fiber is soluble or insoluble. Both are important. Soluble fiber, found in oatmeal, barley, and dried beans, can help lower cholesterol levels. Insoluble fiber, found in whole grains and fruit and vegetable skins, protects against bowel disorders and may help digestion.

Sugars
These simple carbohydrates include glucose, dextrose, fructose, and galactose, all of which provide little nutritional value. Sugar shows up in surprising places, like crackers, "healthy" cereals, and salad dressings. It's often added to foods that need a flavor boost (like low-fat products).

Protein
In general, .45 gram of protein daily per pound of body weight (that's 68 grams for a 150-pound person) is plenty of protein, even if you're breast-feeding or physically active. Most Americans get enough protein effortlessly (unless they're vegetarians). And it's rare for people eating a normal diet to get too much.

Vitamins and Minerals
This list includes the vitamins and minerals found in the food naturally, along with any added to it, and the percentage of daily value for each―again, calculated for a 2,000-calorie-a-day diet. The footnote (not found on all nutrition labels) provides a table listing the total daily grams of fat, cholesterol, sodium, potassium, carbohydrates, and fiber that the USDA recommends in a 2,000- or 2,500-calorie diet.

Ingredients
The product's ingredients must be listed in order of quantity, so the major ones come first. When checking a label on bread, for instance, you want to see that the first ingredient is whole wheat, oats, or some other grain. (Note that "whole wheat" means "whole grain," but not all brown-colored and "multi-grain" breads are made of whole grain.)

Supplemental Vitamins and Minerals
Listed below the ingredients are supplemental nutrients that the manufacturer has added to the food.

Exchange
This information, listed voluntarily by the manufacturer, is for people with diabetes. The food-exchange system categorizes foods into food groups. A nutritionist may counsel a diabetic person to eat eight exchanges of starch per day, for example. A bowl of Cheerios would take up 1½ of those exchanges in a 1,600- to 2,000-calorie-a-day diet.