Proteins are foods that your body can use as building blocks to make muscle or skin or bones. Some foods that have a lot of protein in them are eggs and meat and cheese and beans and fish.
In the ancient world, most people couldn’t afford to eat a lot of meat or fish or eggs, so they got most of their protein from beans and cheese. But it’s really not that hard to get enough protein to live. If you had nothing to eat but bread, and you had enough bread to stay alive on, you would also get enough protein just from the bread.
Learn by doing – a project with protein
More about protein molecules
Bibliography and further reading about protein:
Nutrition: What’s in the Food We Eat, by Dorothy Hinshaw Patent and William Munoz (1992). Easy reading.