The Standard American Diet, appropriately called the SAD diet, does not provide high quality nutrients. It has too much fat, too much protein and too much refined carbohydrates, including sugar. On the other hand, it is low in complex carbohydrates, vitamins, minerals and fiber. Free radicals and their role in development of certain diseases have received a great deal of attention in medical literature in recent years. They have been implicated in a great number of pathological conditions, from arthritis to cancer.
Free radicals are well known enemies of the healthy immune system.
Fortunately, the body has a complex defense system designed specifically for the purpose of fighting free radicals and oxidative damage. It is called antioxidant system. The components of the system are enzymes, vitamins, minerals, and some other nutrients. Allergies to inhalants, foods, environmental chemicals and other substances also affect the function of the immune system. If you are allergic to a particular substance, your body responds inappropriately whenever you are exposed to it.