Protein is a chemical substance which goes to the building of new tissue, new muscle, blood, bone and brain. And this building is something which only proteins can do. There is no substitute for them.
Proteins are building bricks. And if you want a good human house, with good walls, good heating system and first class drains, you must use good bricks and the right kind of bricks. When I say that food is a builder, I mean that it contains protein.
The easiest way of getting the best proteins would be from eating meats which are called animal proteins. The cow eats the grass and turns vegetable proteins into animal proteins. We eat the cow and turn them into human proteins!
There are a number of sources of animal protein – meat, fish, eggs, cheese and milk. So you can see that it does not mean that we must be meat eaters, although I can see no reason for avoiding meat. Milk and cheese and eggs are just as much animal food as flesh.
Animal protein is a particularly good builder and people should be encouraged to eat it regularly. As for vegetable protein, it is found at its best in potatoes, peas, broad beans, bread, lentils, oat meal and split peas.