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Incomplete vs. Complete Proteins


While all proteins you eat contribute to meeting your daily protein requirements, some proteins are better utilized by your body than others. Consuming complete protein in your diet is often beneficial, but it's not entirely necessary. Figuring out how to get the right balance proteins in your diet will help ensure you meet your body's needs.

How They Differ

The main difference between complete and incomplete proteins is that complete proteins contain all essential amino acids your body requires daily, and incomplete proteins only contain some essential amino acids. Your body breaks down the proteins you eat into amino acids, which build and repair tissues in your body, help digest food, provide energy, and perform numerous other body functions. Essential amino acids are also necessary for proper growth in children. Because complete proteins contain all essential amino acids, they are often referred to as high-quality proteins and easily utilized by your body.

Sources of Complete Protein

Animal sources of protein are complete proteins, and some plant foods contain all essential amino acids. Sources of complete animal proteins include milk, yogurt, cheese, meat, poultry, fish, seafood and eggs. Soy protein is a plant-based source of high-quality, complete protein. Grains that contain all essential amino acids and are complete proteins include quinoa and amaranth, according to the Academy of Nutrition and Dietetics.

Sources of Incomplete Proteins

With the exception of the complete plant-based proteins previously mentioned, other plant proteins are incomplete because they provide some, but not all, essential amino acids. Incomplete proteins are found in most grains, nuts, seeds, nut butters, green peas and legumes (such as lentils, chick peas, black beans, pinto beans and navy beans).

Pairing Incomplete Proteins

You don't have to eat complete proteins to get the essential amino acids your body needs. MedlinePlus notes that as long as you consume all essential amino acids over the course of a day, your body can properly utilize those amino acids. However, you do have to carefully plan your diet if you're eating mainly plant-based proteins. The University of Massachusetts notes that generally grains, nuts or seeds can be paired with legumes -- such as black beans and lentils -- to form complete proteins. Examples of such pairings include peanut butter on whole-grain bread, or brown rice with black beans.

Daily Protein Requirements

Chances are even if you're a vegetarian you're consuming at least some complete proteins, and a variety of incomplete proteins during the course of the day. If this is the case and you're meeting your total daily protein needs, your body is likely getting all the essential amino acids it needs. The recommended dietary allowance, or RDA, for protein is 56 grams for men, 46 grams for women, and 71 grams of protein daily for pregnant and nursing women. Active adults often benefit from exceeding these minimum daily needs.


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An experienced health, nutrition and fitness writer, Erin Coleman is a registered and licensed dietitian and holds a dietetics degree from the University of Wisconsin-Madison. She also has worked as a clinical dietitian and health educator in outpatient settings. Erin's work is published on popular health websites, such as and

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