How often do you think about your immune system? Probably not as often as you think about how to avoid the H1N1 swine-flu virus or one of the other viruses afoot these days. If that’s the case, then it’s time to shift your focus. Spending less time thinking about dodging germs and more energy on proactively strengthening your immune system not only helps keep you healthy, it benefits personal wellness on a larger level. “Immunity is not just a defense against sickness; it is synonymous with overall health,” says Kris Somol, ND, an adjunct faculty member at the Bastyr Center for Natural Health in Seattle. “By caring for your immune system, you also heal from injuries faster and prevent chronic disease.” In fact, an underactive immune system is linked to noncontagious diseases, such as cancer. (Cancerous growths can be stunted—or even prevented—by the immune system.)

You might think, given these facts, that you want an immune system that’s ready to mount a defense at the first hint of trouble. And yet, there is such a thing as an overactive immune system. “In some cases, the body fails to recognize harmless invaders, such as pollen, or your own cells as safe and begins attacking them,” Somol explains. This is the case in allergies and autoimmune disorders such as diabetes, lupus, and rheumatoid arthritis. The key to healthy immunity, therefore, is balance. To determine the most effective approaches to boosting immunity, we consulted a spectrum of experts. Here’s what they had to say.

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1| Exercise

Moving, stretching, breathing, strengthening, and working your cardiovascular system are crucial to healthy immune function because physical activity stimulates the flow of lymphatic fluid. The lymphatic system is a series of vessels and glands that transports immune cells and collects waste products throughout the body. Because the lymphatic system has no pump (as the circulatory system has the heart), it relies on muscular contractions to keep things flowing. “Research shows you need at least 150 minutes of exercise per week to maintain health,” Somol says. The most important thing is that you get moving, whether that means walking, biking, dancing, gardening, or taking a class such as tai chi. Yoga, with its inversions that help lymph travel from the extremities, may be an especially effective immune-system booster: A 2007 study found that breast cancer patients enrolled in a yoga program had healthier natural killer-cell counts after chemotherapy—which typically decimates immune cells such as natural killer cells in addition to the cancer cells—than did a control group.

2| Prioritize happiness.

Immunity isn’t just about organs and cells—it has a strong mental component, too, say experts. The ability of stress and depression to lower immunity is so well known that it spawned a new medical field, psychoneuroimmunology, to study the relationship between the mind and the immune system. To help nudge the needle on your personal mood meter in a positive direction, Somol suggests cultivating a “practice of happiness”—devoting time to pursuits that make you feel calm, fulfilled, and at your best, such as a rewarding hobby, socializing with friends, or a contemplative practice that helps you unwind and reflect.

3| Add color to your plate

“Because plants can’t run away from invaders, they have had to develop their own rich immune systems, which are made up primarily of the phytochemicals that give fruits and vegetables their rich color,” says David Heber, MD, PhD, director of the UCLA Center for Human Nutrition and author of What Color Is Your Diet? (Morrow, 2001). The more colors you eat, the more broad spectrum your immunity boost will be. Place special emphasis on red (tomatoes, watermelon, and pink grapefruit), red-purple (grapes, pomegranates, and blueberries), orange (carrots, squash, and sweet potatoes), orange-yellow (oranges, papaya, and nectarines), yellow-green (lettuce, peas, and avocados), green (kale, broccoli, and cabbage), and white-green (celery, pears, and endive). Replacing refined carbs with intensely colored fruits and vegetables also wards off obesity, says Heber, which is a risk factor for numerous chronic diseases.

4| In cold months, avoid cool, raw foods

Traditional Chinese Medicine advises eating as few raw foods as possible during winter. “Raw, cold foods are hard to break down,” explains Sara Frohlich, LAc, an acupuncturist in New York City. “Eating them puts a strain on the digestive system and weakens it over time, which means your body is working harder to get fewer immunity building blocks from your food.” To keep your digestion, and thus your immunity, humming, skip the smoothies, salads, and ice cream, and eat warm, cooked foods whenever possible. Try oatmeal, eggs, or cream of buckwheat for breakfast, soup and half a sandwich on toasted bread for lunch, and lightly sautéed vegetables with lean protein for dinner.

5| Favor aromatic herbs

According to Traditional Chinese Medicine, aromatic herbs—such as garlic, ginger, and scallions—are all warming and help stimulate the body’s defenses. “These strengthen the body’s energy, or qi (pronounced “chee”), open up the sinuses and the chest, and cause a light perspiration which, if you catch a cold, can help ‘sweat it out’,” Frohlich says. Soup seasoned with fresh garlic, ginger, and scallions should be part of your regular menu rotation to strengthen immunity. Add the herbs about halfway through the cooking process, Somol advises. It’s a common misperception that you need to eat garlic raw to get its full antiviral effect, says Somol. “While you don’t want to overcook it, you do want it cooked enough so that the body can digest it.”

6| Prioritize sleep

You’ve heard the conventional wisdom: The body needs seven to eight hours of sleep per night to be at its best. But it isn’t just the morning grogginess you risk by depriving yourself of sleep. Sleep is particularly important to immunity because during this nightly downtime the body is devoted to detox, repair, and healing. In fact, a recent study showed that people who slept less than seven hours a night were nearly three times more likely to get sick after being exposed to the cold virus than those who slept eight hours or more. If you’re having a busy week and simply can’t get an optimal amount of sleep each night, try to make up for it by sleeping in or napping on the weekends, Somol says. “In the short-term, the body can make up for lost sleep and recover healing time that has been lost in the previous few days. It’s when sleep deprivation becomes chronic that it becomes harder for the body to repair itself.”