To maintain good health, efficient immune system is the key factor. It acts like defending army. It helps to protect from all types of diseases from common cold to cancer, keeps allergies in check as well as slows down the aging process. Persons with strong immunity are less prone to diseases.
Poor diet will result in a weakened immune system. Other factors such as stress, smoking, excess alcohol and caffeine, food additives, pesticides, pollution, lack of sleep and exercise also weakens the immune system.
Source: Home Remedy for You