There are a handful of vitamins and minerals that help the immune system in various ways, and many of these can be found in fruits and vegetables. In the last 30 years, studies have uncovered that nutrient deficiencies do, in fact, impair the immune response and lead to frequent, severe infections.

These are the nutrients that have important influences on your immune system:

Vitamin B-6 -- poultry, lean meats, fish, nuts and seeds, and fruits (bananas, avocados, mangos, prune juice, and grapes)

Folic acid -- beans, nuts, all types of dark-green vegetables, and many fruits (orange juice, papaya, banana, mango, kiwi, cantaloupe, and berries). Folic acid-fortified rice, pasta and breads, baked goods, and breakfast cereals are also now excellent sources.

Vitamin C -- Citrus fruits, papaya, strawberries, kiwi, cantaloupe, mango, red peppers, broccoli, brussels sprouts, cauliflower, cabbage, dark-green vegetables of all kinds, tomatoes, and potatoes.

Vitamin A -- All dark-green vegetables and yellow-orange vegetables and fruits are excellent sources of carotenoid forms of vitamin A.

Vitamin E -- wheat germ oil, peanuts, almonds, cod liver oil, soybean oil, canola oil, wheat germ, other nuts, selected fruits and vegetables (mango, Swiss chard, papaya, pumpkin, prunes, grapes, broccoli, spinach, pear, blueberries)

Zinc -- beef, poultry, seafood, nuts and seeds, whole grain breads and cereals, tofu, beans, and milk.

Iron -- shellfish (clams and oysters), pistachios, lean beef, dried beans and peas, eggs, nuts and seeds, dark chicken/turkey meat, dark molasses, prune juice, breads and pasta, and green vegetables.

Selenium -- Brazil nuts, oysters, claims, lean pork and ham, whole grain and regular pasta, chicken and turkey, sunflower seeds, lean beef, breads, oatmeal, soy nuts, eggs, nuts and seeds, and low-fat dairy products.

About 30 percent of elderly patients will have a deficiency in one or more vitamins. Then there are some people who are sensitive to environmental pollutants particularly pollens, car exhaust fumes and dust mites. The answer lies within our immune system. Besides avoiding contact with allergens that may worsen your allergic rhinitis, you should supplement your diet with nutrients like beta-glucan, beta-carotene, vitamins C, E and zinc to boost the immune system, the best defense against allergies.