(2) Vitamins: A trace organic substance that humans and animals must obtain from food in order to maintain normal physiological functions. They cannot be synthesized in the human body and need to be taken from food. Fruits, vegetables, seed foods, animal livers, muscles, fish, cod liver oil, eggs, milk and goat milk are all rich in vitamins.
(3) protein is the basic substance that constitutes human cells; The growth and development of human body and the renewal of tissues are inseparable from protein; Teenagers are in a critical period of growth and development, and there is a great demand for protein. Therefore, teenagers should ensure comprehensive and reasonable nutrition, especially pay attention to the intake of protein. Therefore, they should eat more third-and fourth-grade food in the "Balanced Diet Pagoda", which is rich in protein.
So the answer is: (1) water, inorganic salts, protein, fat, sugar and vitamins.
(2) Scurvy is caused by the lack of vitamin C in the body; Eat more fresh vegetables and fruits.
(3) Teenagers should ensure comprehensive and reasonable nutrition, and pay special attention to the intake of protein.