Many primitive peoples 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 savage tribes believed that eating enemies that had shown bravery in battle would make them brave. Man-eating may have started because people were eager to become as strong and brave as their enemies.
Among civilized people it was once thought that ginger root by some magical power 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.
Later another wrong idea about tomatoes grew up - the idea that they were poisonous. How surprised the people who thought tomatoes poisonous would be if they could know that millions of pounds of tomatoes were supplied to soldiers overseas during World War II.
Even today there are a great many wrong ideas about food. Some of them 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 one has been able to prove that fish is any better for the brain than many other kinds of food.