October 16, 2009
Don't wait until your head is throbbing and a fever is spiking to eat well. It takes time to build up your immune defenses, so start now.
Forget about relying on vitamins and supplements. Research finds they do not prevent flu or colds, although vitamin C can lessen the duration of illness. Whole foods provide real benefit. Emphasize those rich in vitamins A, C and E, as well as selenium, zinc and omega 3 fatty acids. These nutrients work in conjunction with thousands of other minute plant nutrients in foods to bolster the immune system. No one has yet been able to package these powerful nutrients into a supplement in the same mysterious way nature does.
Fruits and vegetables are the powerhouses of protection. Aim to have them at every meal. Add fruit to breakfast or eat it as a snack. Try warming up frozen berries in the microwave and topping with vanilla yogurt. Choose vegetable soups, stews and salads, or oven-roast them. Add a low-sodium V-8 or tomato juice to breakfast or lunch. Frozen vegetables retain their nutrients and can be good options for busy days. Throw some in your work freezer to microwave at lunch. Snack on nuts and dried fruit instead of empty-calorie crackers, fat-free cookies or the like.
Vitamin A is critical to the immune system. It enhances white blood cells and antibodies, and maintains the protective lining of the nose, throat and lungs to prevent virus entry and serious respiratory infections. Milk, liver and eggs are good animal sources. Sweet potato, cantaloupe, broccoli, greens, cabbage, kale, spinach and carrots are good plant sources. Aim for at least one plant serving daily.
Vitamin C increases the production of white cells and interferon, keeping viruses from taking over cells. Aim for at least one good source daily of: fresh orange, grapefruit or equivalent juices, colorful peppers, strawberries, broccoli, kale, cauliflower, greens, Brussels sprouts, papaya, cabbage, spinach, kiwi, snow peas, cantaloupe, tomatoes, zucchini, raspberries, asparagus, celery, pineapple or watermelon.
Selenium protects the thyroid gland and immune cells from damage and keeps them functioning properly. Brazil nuts are the best source (aim for one a day). Good sources are fish, mushrooms, eggs, lamb, barley, sunflower seeds, turkey and oats.
Vitamin E helps in cell signaling and production of antibodies. Green leafy vegetables, wheat germ, sunflower seeds and almonds are very good sources.
Zinc improves production and response of white blood cells, especially in children. Calf liver, mushrooms and spinach are the best sources. Pumpkin seeds, beef, lamb, summer squash, asparagus, chard, collard greens, shrimp, broccoli, peas, yogurt and sesame seeds are good sources.
Omega 3 fatty acids help to regulate the immune system. Eat cold-water fish, flax seeds and walnuts.
Joan Endyke is a registered dietitian with a master's degree in nutrition and food science. She is a certified personal trainer and the nutrition director at Fitness Unlimited.
Readers may send questions about nutrition to Endyke at Fitness Unlimited, 364 Granite Ave., Milton, MA 02186, or by e-mail to firstname.lastname@example.org.
The information in this column is not intended to diagnose individual conditions. Readers should see their doctors about specific problems.