Is Peanut Butter a Complete Protein?

Amino acids are known as the building blocks of life. Growth and repair of the body requires the availability and utilization of amino acids. Your body needs a combination of 21 amino acids to stay healthy. While your body can manufacture some of the amino acids it needs, your diet must supply others, which are classified as essential amino acids. A complete protein contains all nine of the essential amino acids. All animal products contain every essential amino acid, while plant products generally lack one or more.

When a protein lacks one or more of the nine essential amino acids, it is known as an incomplete protein. Peanut butter lacks the essential amino acid methionine but is high in lysine. All plant-based proteins are incomplete protein sources except for soy and quinoa. You can still obtain all the essential amino acids even if you do not consume complete proteins by combining more than one plant-based protein within a 24-hour period. For example, if you consume peanut butter with a grain, such as bread, you're consuming all nine essential amino acids you need for the day.

While peanut butter does not contain all nine essential amino acids to make it a complete protein, it does supply essential nutrients such as dietary fiber, vitamins and minerals. Peanut butter also contains healthy fats, such as monounsaturated and polyunsaturated fats, which your body needs to stay healthy. Peanut butter is still an excellent source of protein. Two tablespoons contain 8 grams of protein, which is about 16 percent of the amount of protein you need daily. Approximately 10 to 35 percent of your daily caloric intake should come from protein, according to the Centers for Disease Control and Prevention.

You do not have to consume essential amino acids at every meal as long as you get a balance of all nine throughout the day. Since peanut butter is such an excellent source of protein and other nutrients, try making it part of your diet despite it not being a complete protein. While peanut butter lacks three essential amino acids, you can obtain those amino acids in other foods such as grains or animal products. To get all your essential amino acids in your diet, you need to consume complementary foods -- but not necessarily at the same time. When you consume these foods throughout the day, you are getting all the essential amino acids your body needs to stay healthy.