Complete proteins from plant-based sources

The most commonly known sources of proteins for vegetarians, especially for vegans who avoid all animal-based foods, including eggs and dairy, are legumes like beans and peas. However, legumes are not the sole source of proteins for vegans. Vegetables, grains, nuts, and seeds are all important sources as well. In fact, it is important for vegans to include all of them in the diet to make them “complete”.

Complete Vegetarian Proteins

Complete Vegetarian Proteins

Essential Amino Acids and Plant Proteins

Proteins are made up from amino acids. There is a total of 22 amino acids, of which 9 of them are considered essential amino acids [1]. These nine are “essential” or “Indispensable” since the body is not able to make them. These essential amino acids must be supplied by the food we eat. Body cells are constantly wearing out and in need of replacement. Proteins are the basic materials for every cell in the body. Therefore, an adequate supply of proteins is necessary for growth, development, and health maintenance.

The 9 Essential Amino Acids
Histidine Isoleucine
Leucine Lysine
Methionine Phenylalanine
Threonine Tryptophan
Valine

Animal proteins such as meat, fish, eggs, milk and cheese contain all the essential amino acids required by the body, therefore, they are considered “complete” proteins. However, in plant-based sources, certain essential amino acids may be limited. Therefore, it is important to consume a mixed diet, which include legumes, vegetables, grains, as well as nuts and seeds. The combinations of foods provide sufficient amino acids and compensate for any shortages in any particular groups [1]. The following table shows how food combination can be used to compensate for limiting amino acids.

Food combination to compensate limiting amino acids
Plant food Limiting Amino Acids Complementary Food Example
Grains Lysine;Threonine Legumes (Beans) Baked beans and toasts
Nuts and seeds Lysine Legumes (Beans) Stir-fry green beans with sesame seeds
Legumes (Beans) Methionine Grains; nuts & seeds Lentil dhal and rice
Corns Tryptophan Legumes (Beans) Corns and kidney beans and corns salad
Vegetables Methionine Grains; nuts & seeds Vegetables and cashew nuts soup

Here are some examples of high protein foods in each of the group of legumes, vegetables, grains, nuts & seeds

Legumes

Vegetables

Grains

Nuts and Seeds

References

[1]         M.E. Barasi, Nutrition at a Glance, Blackwell Publishing, Oxford, England, 2007.

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