b'Chapter 4Just like any of our bodily processes, our immune system relies upon good nutrition to function at its best. Optimal digestion occurs when we chew our food thoroughly, eat in a relaxed manner, eat nutrient-rich foods that contain their own enzymes (raw foods), and avoid processed and synthetic foods that can inflame the digestive tract and do not contain sufficient immune-enhancing nutrients. The Rainbow DietCreating a rainbow of color on your plate is one of the best ways to build a healthy immune system. The natural colors found in fruits and vegetables are the result of pigmented compounds called flavonoids. Each unique flavonoid provides its own antioxidative and immune-supporting actions. People who eat at least six servings of high-antioxidant vegetables daily have decreased oxidative damage to their cells. By eating a wide variety of colorful fruits and vegetables, you are consuming a full spectrum of antioxidative flavonoids. One category of flavonoids is made up of anthocyanidins and proanthocyanidin oligomers (PCOs), which are found in blue and purple berries such as blueberries, grapes, cherries, and blackberries. Quercetin is another flavonoid found in almost all vegetables and fruits, and is especially concentrated in onions and apples. Isoflavonoids, yet another type of flavonoids, are found in foods such as soy. Isoflavonoids exert hormonal activities in addition to their antioxidant actions. Citrus bioflavonoids are another important group of flavonoids that work synergistically with vitamin C. Any fruit or vegetable of color contains a substantial quantity of flavonoids. Consuming a variety of colors provides the body with the greatest balance of flavonoids. In addition to flavonoids, fruits and vegetables contain important immune-enhancing vitamins and minerals. These include zinc, vitamin E, vitamin D, sterols, and carotenes such as vitamin A and lycopene. IMMUNITY7'