Topic 2 Main sources of protein in a vegetarian/vegan diet

In a vegan/vegetarian diet, all main meals should include a serving of protein. While ovolactovegetarians can consume eggs and dairy products, the options seem more limited for strict vegetarians and vegans.

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Legumes represent the main source of protein in vegan/vegetarian diets. Indeed, the quality of protein of legumes is similar to that of meat in chickpeas and soy.

Legumes and cereals were considered “incomplete foods” because they are deficient in methionine and lysine respectively. For that reason, it has been classically recommended that, to obtain a complete protein, legumes and cereals be combined in the same dish. Nowadays it is known that it is not necessary to consume legumes and cereal in the same meal to obtain a complete protein and that it is enough to ingest legumes and cereal throughout the day.

Between cereals and legumes, we find the quinoa, a pseudocereal rich in protein that also contains methionine.

Here are some ideas for introducing legumes into the diet in a diverse way:

Tofu is made with soybeans, water and a gelling plant. In the market there are different kinds of tofu such as with fine herbs, tomato, basil, sesame, olives, smoked … The firmness of tofu depends on the amount of water it contains. Softer tofu (like silken tofu) has a higher water content and, therefore, its nutrient content for the same amount of product is lower.

The quality of the protein of tofu is very good, since it preserves the entire aminogram of soy. It provides between 11 and 16 g of protein per 100 g of product, that is, similar to egg (13 g per 100 g) and more than yogurt (10 g per 100 g). Besides, tofu is digested more easily than soybeans.

The detractors of tofu mainly complain about its poor taste. That’s why we propose some ideas to cook tofu in a tasty way:

Tempeh is a food product from the natural fermentation of soybeans. Being a fermented product, it is especially good for the intestinal flora. Tempeh is firmer than tofu and has a strong flavor. From a nutritional point of view, tempeh is more complete than tofu; it contains about 19 g of protein per 100 g of product, has a higher fiber content and is rich in minerals.

Textured soy is obtained by extruding degreased soy flour obtained as a sub-product of soy oil extraction. Textured soy is equally rich in protein, minerals, vitamins, and fiber. It is usually purchased in dehydrated form. To cook it, it must be mixed with water, after which it acquires a fluffy texture.

Nuts are a very healthy snack, and, in vegan/vegetarian diets, they represent an extra source of protein. The nuts with the highest protein content are peanuts and almonds, followed by pistachios and cashews. The list would be completed by walnuts, pine nuts and hazelnuts.

Young children should not consume whole nuts, but there are many other ways to introduce nuts into their diet.

Seitan is a preparation from wheat gluten, so it is not suitable for people with coeliac disease. Its texture similar to meat and its versatility allow it to be introduced into a large number of dishes. Seitan contains a high amount of protein, but being a cereal derivative, they are of lower biological value than those of tofu or tempeh.

This video shows how to prepare a marinated seitan

In recent years, different products have emerged to cover protein needs in vegan/vegetarian diets. They are usually marketed as substitutes of meat because they have a similar texture and can be cooked in a similar way. Although they do not provide added benefits to the first- (tofu, tempeh and seitan) or second-generation plant protein (textured soy), their versatility and easy preparation have made the third-generation plant protein have a greater acceptance.

Among these third-generation plant protein stand out heura, a soy beans derivative, and quorn, made from the mycoprotein of the fungus Fusarium venenatum. Initially, “heura” and “quorn” were born as registered trademarks, but now they serve to generically name this type of products  that, colloquially, are known as “vegetable meats”.

One of the negative aspects of this type of products is their degree of processing. Unlike first- and second-generation vegetable proteins, in the case of “vegetable meats, the consumer do not buy the ingredients, but a pre-cooked meal which is, indeed, an ultra-processed product.