Practically all foods give this fuel or energy, but some give much more than others. Fats give more fuel than an equal weight of any other food. Sugar and foods rich in starch like flour and corn meal are fuel foods. This is one of the reasons why they are chosen to be shipped abroad. The cereals always supply an important part of the fuel of the diet. Watery foods, like many vegetables and fruits, normally give less fuel. A person could not live on lettuce any better than a house could be heated with tissue paper. If the food does not supply enough energy, a person will burn up part of his own body for fuel and will grow emaciated. Far too often we find children of the very poor who are undernourished because of lack of food fuel. Sometimes even well-to-do young people half starve themselves because they get "notions" about food. One of the terrible tragedies abroad is the hundreds and thousands of men and women and children who are worn and thin and sick for lack of food. We need food, too, to keep the organs of the body running smoothly. Abroad, people are suffering not only because they have not enough food, but because they have not the right kinds of food. Milk and vegetables and fruits are especially useful. They are the chief sources of the much-needed _mineral salts_ and the two _vitamines_. The vitamines are substances of great importance about which has centred much discussion lately and which scientists do not yet fully understand, though they realize that they are essential for the growth of children and for health in adults. The _protein_ of food is used to build the body if we are young, and to restore the daily wear and tear if we are older. The mineral salts are also necessary for this purpose. Protein will be discussed further in the chapter on meat and meat substitutes, but it should be realized here that the protein we eat comes not only from these foods, but also from the cereals. Cereals supply a full half of the protein of many diets. Cereals are therefore important for their fuel since they are rich in starch, and for their protein, and, if we eat the entire kernel, for their mineral matter and vitamines. They also have the pleasant flavor and texture which we have grown to like. Wheat is no better than any of the other cereals. It possesses absolutely no nutritional advantage for man or beast over oats, corn, and rye. It has no more protein, and no better protein. It has no more fat and no better fat. It has no better mineral salts and in no larger amounts. It has no more fuel or better fuel. It is just _one_ of the cereals, and there is not the slightest evidence that it is the best one. It has merely become one of our habits.