Animal protein foods include meat, poultry, fish, dairy products and eggs and are said to be of high biological value. Plant protein sources, although good for certain essential amino acids, do not always offer all nine essential amino acids in a single given food. For example, legumes lack methionine, while grains lack lysine. What is needed are complementary proteins , various protein food sources that, eaten together, enable a person to meet the standards of a high biologic protein diet. There are two types of vegetarians.
Lacto vegetarians eat animal protein of high biological value, eggs and dairy products.
They don't have to eat all these food items at a given meal. However, they should consume most or all of them during the course of the day to insure a well balanced protein diet of high biological value. The typical American diet, as we said earlier, is already providing plenty of protein. There is no value in adding even more protein to that amount, since protein cannot be stored in the body and the excess is eliminated in urine and feces. This is even more of a concern as we get older and our organs are less efficient and effective.