The main ethical reason for requiring a special diets is vegetarianism.
There are two main types of vegetarians:
Vegans believe it is ethically wrong to eat animals that are reared and slaughtered for the purpose of providing food for humans. They avoid all animal products including eggs, cheese or milk. They follow a strict diet that includes only plant foods 鈥 fruit, vegetables, pulses, grains and nuts.
Lacto-ovo vegetarians will not eat the flesh of animals but they will drink milk and eat eggs because the animal does not suffer to produce these. They also eat all of the plant food eaten by vegans.