part 4

30 Milk is the best food there is for babies. It is good for children and for older people too. It has in it fat, which gives energy, and it has the most important of the materials needed for building up our bodies. Milk makes strong bones and strong teeth too. It is good for a child to drink two or three glasses of it every day. In addition, milk has in it most of the vitamins which are needed to keep us healthy. Vitamins are a discovery of the twentieth century. Two hundred years ago no one knew anything about them.

31 The vitamins are named by letters of the alphabet. Vitamin A is needed by the eyes. There is Vitamin A in milk, butter and green vegetables. It can be stored by the body. Vitamin B cannot be stored. It must be supplied all the time by some of the food we eat. The skins of grain of all sorts have Vitamin B in them.

32 Vitamin C is very important to the body. Without it our teeth become loose and our arms and legs weak. Lemons, oranges and tomatoes have Vitamin C in them. Vitamin D is the sun vitamin. We get it in milk and eggs and from sunlight on our skin. There are other vitamins, but these, A, B, C and D, are the most important.

33 Every person must have air and water and food to keep alive and must have these vitamins to keep well. How do we know this? How do we know what food keeps us well and healthy? We know from the effects on us and on animals of going without one sort of food or another. That is how we see which foods give us energy, which make us fat and which make us able to keep healthy. Scientists are putting together more and more knowledge about the sorts and amounts of food that our bodies need. Too little food or too much of the wrong food is bad for a person. The right amount of the food will keep a person feeling well and strong. Some people need a little more or a little less of one or another sort of food than others.

34 Where do we get our food? We get much of it from the earth. We use some sorts of animals and birds to give us food. Great parts of the earth are covered with grass, a plant which grows with narrow green leaves and puts down roots quickly. There are more than three thousand different sorts of grasses growing. Grass has very small seeds which are used as food by birds and small animals. We have discovered how to grow grasses with larger seeds. Wheat, rice, corn, and other grains come from grass. The grain lands of the world have been planted by people. From grain we get an important part of the food that gives us energy.

35 The grasslands of the earth supply food to many different animals. From some of them we get meat and milk. From milk we make butter and cheese and other foods. From birds living on grain we get eggs and meat. Seeds planted in good earth supply grains and fruits and vegetables of many sorts. The seas and rivers supply fish and some sea plants for food.