What’s the Difference Between Complete and Incomplete Protein?


Protein is a crucial part of your body, used to create and repair tissues, build muscle, make enzymes and hormones and keep your bones, skin and hair healthy. But do you know the difference between complete and incomplete proteins?


A complete protein contains all the essential amino acids your body needs. Luckily, there are plenty of protein sources that offer complete proteins, whether you’re an animal lover or a vegan.

Animal-Based Proteins

Proteins are long chains of amino acids (think alphabet bead necklace), and your body can make several of them from other raw materials it has on hand. But nine amino acid building blocks, called essential amino acids, cannot be made in your body, so they must come from food. When your meals contain enough of the nine essential amino acids, they are considered complete proteins.

Animal foods such as dairy, eggs, fish and meats are complete proteins. But there are also a number of plant-based foods that are complete proteins, including soy products such as tofu and tempeh, beans such as lentils and green peas, quinoa and buckwheat.

While some experts have criticized plant proteins for not being complete, the truth is that most can be combined to produce a meal with sufficient levels of all nine essential amino acids. And, in fact, the key to achieving the protein needs of most people is a combination of plant sources, rather than just one source. This approach was first advocated in a 1971 book, Diet for a Small Planet, by Frances Moore Lappe. She suggested strategically pairing plant proteins at each meal in order to create a protein pattern that mimicked the amino acid profile of an animal protein, such as whey.

Plant-Based Proteins

Proteins in plant foods are incomplete because they don’t contain all nine essential amino acids. However, many people who eat vegetarian or vegan diets can meet their protein needs by eating a wide variety of plant proteins throughout the day to get all the amino acids they need.

단백질보충제 Foods like legumes (beans, peas and lentils), whole grains (quinoa, amaranth, barley and wheat), nuts and seeds (flaxseed, chia seeds, pumpkin seeds and hemp seeds) can provide complete protein. You can also find complete proteins in fortified plant milks, yogurts and cheeses (such as soy and almond), nut butters and seitan.

If you’re a vegan or vegetarian, try adding dairy and eggs to your daily meals to get the full range of essential amino acids. You can also add in plant-based foods that are naturally high in amino acids, such as quinoa and soybeans. Quinoa, pictured above, is a delicious grain that can be eaten on its own or mixed with other ingredients to create savory dishes and desserts. You can also find complete proteins in soy products, such as tofu and tempeh. But be careful consuming too much soy, as it can mimic estrogen in the body, which is not healthy for those with certain hormone health conditions.

Vegetarian/Vegan Proteins

Whether you eat meat or not, it’s important to eat a variety of protein sources. Your body needs protein to form and transport nutrients and build and repair tissue. The human body creates 13 of its 22 amino acids on its own, but it must get the other nine from food. Animal proteins are complete, but many plant foods, such as soy products and quinoa, are also complete. The days when vegetarians and vegans had to worry about combining incomplete proteins to meet their protein needs are long gone.

A protein-rich whole grain, such as brown rice, oats, 100% whole wheat pasta or bulgur, can be combined with beans, lentils or peanuts to make a complete protein. You can also find complete protein in a vegan protein powder, which usually contains a combination of different protein sources.

The latest research suggests that if you choose a well-planned, balanced diet, you don’t have to worry about getting enough complete protein from animal sources. However, it’s still a good idea to limit processed meat and dairy to avoid the extra saturated fat and added sodium they contain. And if you’re considering a vegan diet, talk to your doctor before making such a dramatic change in your diet.

Combining Proteins

Proteins are like the shapeshifting workhorses of the body, doing everything from fending off disease as antibodies3 to digesting food4 as enzymes. They’re essentially chains of amino acids, and in order to be considered complete, a protein must contain adequate amounts of all nine essential amino acids.

Eleven of these are naturally produced by the body and are considered nonessential amino acids, while the remaining nine must come from food. Most animal foods are considered complete proteins, but many plant-based foods don’t contain all nine essential amino acids—they tend to be low in one or two of these crucial aminos, which makes them incomplete protein sources.

However, many of these plant-based foods are rich in other nutrients that make them good for you and help to create a protein source that’s complete. These foods include legumes (beans, peas, lentils, chickpeas), soy products like tempeh and tofu, whole grains (quinoa, barley, buckwheat, freekeh, amaranth) as well as vegetables, nuts, seeds and some whole fruits.

It used to be thought that you needed to eat complementary proteins together at each meal in order to get all the essential amino acids, but it is now known that as long as you eat a wide variety of plant-based and animal foods throughout the day, your protein intake will be sufficient. This is why a healthy, balanced diet is so important.