The Natural Nutritionist

Because sniffle season will soon be upon us, odds are you'll be fielding questions from customers about how they can ramp up their immune systems. The good news: Showing them your store's selection of healthy, whole foods can give them the answers they're looking for.

While the immune system's ability to fend off and respond to germs depends on many things, including levels of stress, physical fitness and sleep, food is considered one of the most important factors in the immune system's effectiveness. Nutrient deficiencies have a significant impact on immune power. The big picture for an immune-boosting diet includes lean proteins, colorful fruits and vegetables, a variety of whole grains and beans, as well as nuts and seeds. However, certain nutrients are specifically linked with boosting immunity.

Omega-3 fatty acids
These fats, found in some fish (herring, salmon, tuna, trout, mackerel, oysters and sardines) and certain plant foods (flaxseed, walnuts, canola oil, soynuts and soybean oil), may increase the activity of white blood cells, which defend the body against infectious disease and foreign mater?ials. Omega-3s have also been shown to suppress inflammation—another culprit when it comes to congestion and colds. Research shows it's a balance between omega-3s and omega-6s (found in vegetable fats like corn and sunflower oil, and in a lot of processed foods) that benefits the immune system.

Vitamins A (beta-carotene), C and E
All three vitamins improve the production and function of white blood cells and protect immune cells from the damage free radicals can wield. In addition, beta-carotene (found in carrots, pumpkins, sweet potatoes, winter squash, cantaloupe, spinach and apricots) is important for the integrity of cells in the skin, lungs, mouth, nose and digestive tract—the healthier these cells, the better the barrier they form against bacteria and viruses. Vitamin C (found in citrus fruits, strawberries, tomatoes, kiwi, red pepper and red cabbage) may offer an antihistamine-like effect that can reduce the severity and duration of a cold. Vitamin E can be found in vegetable and seed oils, seeds, nuts and wheat germ.

Iron, zinc and selenium
Iron (found in clams, oysters, pumpkin seeds, beef and pistachios) and selenium (in nuts, seeds, pork, whole grains and poultry) help form enzymes and antibodies that fight off infection. Zinc (in oysters, beef, nuts, seeds and soybeans) steps up to battle viruses and bacteria too. It's also been shown to support the thymus, an organ housed in front of the heart, which stimulates the production of infection-fighting cells and houses them for later use. As we age, the thymus shrinks, and zinc may help counteract the aging effect.

Prebiotics and probiotics
Our intestinal tract is a battleground for good and bad bacteria. The good bacteria boost the strength of the immune system by guarding against intestinal infec?t?ions. Pre- and probiotics can nudge out the bad bugs and create a more immune-friendly environment for good bacteria to thrive. Look to berries, bananas, dark leafy greens and whole grains (especially oatmeal, flax and barley) for prebiotics; yogurt, kefir, tempeh, miso, sauerkraut and other fermented foods pack the most probiotics.

Of course, all of these good foods won't work to ward off illness if they're paired with junk food. A diet high in saturated fat, sugars and processed foods may limit the activity of the immune system. Yo-yo dieting may suppress it as well, with some research suggesting it sidelines certain immune cells that otherwise could have helped stop the spread of germs in the body.

Getting the most from our immune systems boils down to creating healthy lifestyle habits, including eating well. This fall, help your shoppers pick the foods that will pack the most powerful immune-enhancing punch.

Susan Moores, M.S., R.D., runs SDM Communications, a consulting firm specializing in food and health issues. E-mail her at [email protected] or call 651.653.4794.

Natural Foods Merchandiser volume XXVIII/number 10/p. 30