Animal proteins are called complete proteins because they naturally contain all nine essential amino acids in each serving. If you’re on a vegan or vegetarian diet, you probably need to eat a variety of food to get all the right combos of essential and nonessential amino acids.

There are 20 different amino acids – nine of which are called “essential” and 11 of which are labeled as “non-essential.” The human body needs all 20 of these amino acids, in varying degrees, to be healthy and fully functional. All 20 have distinct chemical structures and are used for different roles – such as forming neurotransmitters, forming hormones and producing energy. But their primary role is to build proteins.

Protein is part of every single cell in the human body and is essential to the body’s functioning. Protein helps build and repair tissues like skin and muscle, and it helps produce antibodies and insulin. From only 20 amino acids, the body is able to generate many thousands of unique proteins with different functions.

Essential Amino Acids

These are the nine amino acids that your body cannot create on its own, and that you must obtain by eating various foods. Adults need to eat foods that contain the following eight amino acids: methionine, valine, tryptophan, isoleucine, leucine, lysine, threonine and phenylalanine. Histidine, the ninth amino acid, is only necessary for babies.

Instead of storing up a supply of the essential acids, the body uses them to create new proteins on a regular basis. Therefore, the body needs a continual – ideally daily – supply of these amino acids to stay healthy.

Non-Essential Amino Acids

The other type is the non-essential amino acid, 11 of which exist and are synthesised by the body. Thus, although they are an important part of building proteins, they do not need to be included in an everyday diet. Eight of these non-essential acids are also known as “conditional,” meaning that the body may not be capable of producing enough of them when presented with substantial stress or illness.

So now – the big question. How do we make sure that we are meeting our body’s amino acid requirements through our diet? The answer is surprisingly simple enough – all we have to do is eat a recommended amount of protein each day and consume a variety of whole foods.

Incomplete proteins

Plant proteins, with the exception of quinoa and a few others, a naturally lower in some of the essential amino acids, and are therefore called incomplete proteins. However, by eating a diverse diet of vegetables, grains, and legumes, you can easily create complete proteins. Another great option is including full-protein, complete food meaning it contains all the 9 essentials amino acid the body cannot make such as quinoa, buckwheat, hemp seeds, chia seeds.

A common belief is that most plant foods are completely devoid of at least one essential amino acid, but the truth is that all plant proteins have some of every essential amino acid. As a general rule, legumes are lower in the amino acid methionine while most other plants foods are lower in lysine. In general, though, only lysine is likely to be a concern for most vegans because almost all vegans naturally eat plenty of foods high in methionine.

In an effort to make sure vegetarians were getting enough of all the amino acids, in the early 1970s in her book Diet for a Small Planet, Frances Moore Lappe popularised the idea of combining plant proteins at each meal in order to get a “complete” protein. The idea was that mixing beans and grains would allow you to ensure that you’re getting both methionine and lysine at each meal.

Good to know:

Beans

While beans are normally low in the amino acid methionine, soy is a complete protein and thoroughly deserves its status as the go-to meat substitute. Tempeh and natto are also made by fermenting the beans, but tofu is probably the best-known soy product. If protein’s a concern, it’s important to choose the firmest tofu available — the firmer the tofu, the higher its protein content.

Spirulina with grains or nuts

Contrary to popular belief, this member of the algae family is not a complete protein, since it’s lacking in lysine, methionine, and histidine. To remedy that, just add something with plenty of those amino acids, such as grains, oats, nuts, or seeds.

Protein: 4 grams per 1 tablespoon