Eight amino acids which in a human body can't be synthesized are called irreplaceable. Their receipt in an organism with food is just necessary. There is a popular belief that these amino acids contain only in meat and dairy products. However this delusion. All substances, necessary for activity, can be received also from the vegetarian menu.
Plants, unlike animals, possess unique function of synthesis of protein from water, air, the soil. Plants can synthesize also essential amino acids, and an organism of any animal, as well as the person, can't do it. Therefore, the primary source of protein and amino acids is vegetation.
Animal protein is very hard acquired by an organism without auxiliary elements – the chlorophyll, carbohydrates, vitamins, minerals, in large numbers which are contained in a plant food. Respectively the plant proteinaceous food is also its source and a complex of additional necessary substances for its assimilation.
The main vegetable source of amino acids is, of course, beans, first of all, soy. They contain all eight essential amino acids. Beans, probably, the only type of a plant food containing such substances as threonine and phenylalanine. But nevertheless the culinary choice isn't so poor, there is a set of types of beans: peas, soy, haricot, lentil, chick-pea, маш and others.
Other amino acids besides beans can be received from nuts, sunflower seeds, sesame. These products are very rich with digestible protein and contain a set of other useful substances.
Such irreplaceable substance as valine, contains, for example, in mushrooms, and tryptophane - in bananas and dates.
The children's organism requires two additional essential amino acids - arginine and a histidine. They can easily be found in all types of beans, nuts and sunflower seeds.
You shouldn't forget that the organism besides amino acids needs a set of other substances and vitamins therefore it is necessary to watch balance of a diet constantly.