Many primitive people believed that by eating an animal they could get some of the good qualities of that animal for themselves. They thought, for example, that eating deer would make them run as fast as the deer. Some tribes （部落） even ate enemies that had shown bravery in battles.
Among civilized people it was once thought that ginger roots could improve the memory. Eggs were thought to make the voice pretty. Tomatoes also were believed to have magical powers. They were called love apples and were supposed to make people who ate them fall in love.
Even today there are a great many wrong ideas about food, some of which are very widespread.
One such idea is that fish is the best brain food. Fish is good brain food just as it is good muscle food and skin food and bone food. But no scientist has been able to prove that fish is any better for the brain than many other kinds of food.
Another such idea is that you should not drink water with meals. Scientists tell us that washing food down with water as a substitute for chewing is not a good idea, but some water with meals has been found to be helpful. It makes the digestive juices flow more freely and helps to digest the food.
Many of the ideas that have to do with mixtures of foods have no scientific foundation. A few years ago, the belief became general that orange juice and milk should never be drunk at the same meal. The reason given was that the acid in the orange juice would make the milk curdle （结团） and become indigestible. As a matter of fact, experts confirm milk always meets in the stomach a digestive juice which curdle it; in fact, the curdling of the milk is the first step in its digestion. A similar wrong idea is that fish and ice cream when eaten at the same meal form a poisonous combination.