Protein
A 2-tablespoon serving of peanut butter contains 7 grams of protein. Your body uses the amino acids found in protein to build and repair muscle tissue. In addition to building metabolism-boosting muscles, protein-rich foods like peanut butter keep you feeling fuller for longer. The protein in peanuts, like other plant proteins, contains an incomplete set of amino acids, so you should have a glass of milk with your peanut butter sandwich to complete the set, recommends sports nutritionist Nancy Clark.
Healthy Fats
Peanut butter contains the same ratio of saturated to unsaturated fats as olive oil, says Harvard Medical School. The poly- and monounsaturated fats in the spread lower your risk of developing heart disease by reducing the amount of harmful cholesterol in your bloodstream, and also prevent type 2 diabetes. Each 2-tablespoon serving contains 16 grams of total fat, including 7.4 grams of monounsaturated fat and 4.5 grams of polyunsaturated fat.
Potassium
Excess sodium in your diet puts stress on your cardiovascular system, but potassium can counter the negative effects of sodium. It also helps your nerves function properly and aids in heart function. Peanut butter brands with added salt contain two times more potassium than sodium, and unsalted varieties are even more heart-healthy, says Harvard Medical School. Consuming 2 tablespoons of peanut butter boosts your potassium intake by 238 milligrams.
Fiber
A 2-tablespoon serving of peanut butter contains about 2 grams of dietary fiber. While not the most fiber-rich of foods, peanut butter can help supplement your fiber intake from other foods. Fiber helps regulate your digestive system by promoting healthy bowel movements, and, like protein, fiber keeps your hunger at bay between meals. The fiber in peanut butter also fights heart disease, type 2 diabetes and obesity.