Become a Member

Get access to more than 30 brands, premium video, exclusive content, events, mapping, and more.

Already have an account? Sign In

Become a Member

Get access to more than 30 brands, premium video, exclusive content, events, mapping, and more.

Already have an account? Sign In




What to eat and how to live for healthy immune function.

Heading out the door? Read this article on the new Outside+ app available now on iOS devices for members! Download the app.

We’re in the middle of winter cold and flu season, and inside your body, a series of small battles is being waged. The army, your immune system, is made up of a number of key players, all dedicated to protecting you from foreign invaders. How to keep immunity healthy and balanced?

Here’s the best advice on what to eat, what to avoid, how to move, and how to live.

What to Eat

The immune system is like an army protecting the body from foreign invaders, and it’s important to keep the soldiers well nourished. The best defense is a balanced diet, with ample amounts of certain key nutrients. Some of the most important:

  • Brazil nuts. They’re high in selenium, a powerful antioxidant that has been shown in a number of studies to significantly improve immune response. Other good sources of selenium include halibut, turkey and sardines. Easy fixes: chop Brazil nuts and add to steamed quinoa; purée Brazil nuts, garlic, fresh basil, and olive oil for pesto.
  • Oysters are the richest source of zinc, an antioxidant mineral that’s essential for immune cell function. Many studies have shown that even mild zinc deficiency depresses immunity. Beef, crab, turkey, and kidney beans are other good sources of zinc. Easy fixes: add oysters to stuffing recipes; combine oysters, crab, and fish in a seafood stew.
  • Pumpkin is rich in vitamin A, which enhances immune functions, such as white blood cell activity. Vitamin A also has antioxidant properties, and studies have shown that a deficiency increases risk of infectious disease. Carrots, sweet potatoes, spinach, collards, and kale are also high in vitamin A. Easy fixes: add puréed pumpkin to pasta sauce, halve sugar pie pumpkins and roast until tender.
  • Sunflower seeds are rich in vitamin E, essential for overall immune function; in studies, even a small vitamin E deficiency impaired immune response. Other good sources of vitamin E: almonds, turnip greens, spinach, and beet greens. Easy fixes: purée sunflower seeds with cooked artichokes, swap sunflower butter for peanut butter on sandwiches.
  • Papayas are rich in vitamin C, long recognized for its immune-enhancing effects. Studies have shown that vitamin C improves many components of the immune system, including natural killer cell activities. Strawberries, grapefruit juice, peaches, peppers, broccoli, and Brussels sprouts are other good sources. Easy fixes: add frozen papaya cubes to smoothies; combine chopped papayas and peaches with minced jalapeños, red onion, and lime juice for salsa.

Red peppers contain vitamin B6, which is necessary for production of several important immune system cells. Other good B6 sources: tuna, spinach, cod, bananas, soy, and beans. Easy fixes: purée roasted red peppers and white beans for a quick dip; add minced red peppers to tuna salad.

How to Live

Diet, exercise, and supplements can go a long way toward boosting resistance and improving immune system function. But that’s only part of the story; if you’re sleeping too little and stressing too much, you’ll impact your immune system. Some important tips on how to live to boost resistance:

  • Reduce stress. It’s one of the most important factors for improving immune function. Researchers have known for years that a wide variety of conditions and illnesses, from digestive disorders to heart disease, are linked to emotional stress. Most studies show that chronic, long-term stress—versus sudden, short-lived, intense stress—causes more damage to the immune system. Stress may impact immunity by disrupting communication between the immune system and other body systems, by causing a chronic release of stress hormones, like cortisol, that affect immune regulation, or by decreasing T-cell activity.
  • Have close friends. In an early and famous experiment on immune response and social life, researchers exposed healthy volunteers to the cold virus, and found that those with stronger social networks and friendships were less likely to develop colds. Other studies have consistently linked a strong support system with better immune function, as well as lower blood pressure and reduced mortality.
  • Laugh. A good belly laugh can boost immunity and increase natural endorphins, the body’s natural feel-good chemicals. In one recent study, laughter appeared to specifically impact the activity of natural killer cells. Rent a funny movie, go to a comedy show, invite your funniest friend to lunch. Your immune system will thank you.

Meditate, with love. Mindfulness-based meditation practices have been linked with improved immune function in many studies. One recent study also noted that similar practices, called loving-kindness meditation and compassion meditation—geared toward encouraging a loving, kind mindset—improved immune response.

What to Avoid

Some foods, toxins, and drugs upset immune system balance and deplete the body’s ability to ward off toxins. The worst offenders:

  • Sugar decreases the ability of white blood cells to engulf bacteria—in some studies as much as 40 percent. White sugar is the worst, but large amounts of any concentrated sweetener—including honey, agave, and maple syrup—have similar actions. Same with pasta, bread, and other refined carbohydrates that lack adequate fiber to slow the release of glucose into the bloodstream. Stick to low-glycemic carbs, like sweet potatoes, quinoa, oat groats, buckwheat and beans, and use sugar in moderation.
  • Alcohol. Drinking wine, beer, and hard liquor hampers immunity in much the same way as sugar: by reducing the ability of white blood cells to fight pathogens. Excessive alcohol intake—three drinks or more—also inhibits the ability of white blood cells to protect against cancer. Additionally, heavy drinking usually results in deficiencies of key immune-boosting nutrients. Stick to one drink a day, or less; if you’re drinking red wine for the health benefits, switch to red grape juice to get the same heart-healthy antioxidants (mainly resveratrol).
  • Allergenic foods. Food allergies, or even sensitivities, stress the immune system; the most common offenders are gluten, dairy, corn, soy, and peanuts. Food additives like artificial colors, preservatives, and pesticide residues, may also cause sensitivities. Focus on whole, unprocessed foods (those without a label); if you suspect that you’re allergic to a food, work with a nutritionist to identify offending foods.
  • Coffee. In excess, coffee and other significant sources of caffeine tax the adrenal glands and central nervous system, increasing stress—which directly impacts immune function. Limit intake, or try combining half of the coffee grounds you’d normally use with an herbal coffee substitute, and brew as usual.
  • Obesity. Some studies suggest that excessive amounts of stored fat in the body trigger inflammation and upset the immune system; one theory is that some fatty acids “look” like bacterial invaders, leading the body to believe they’re foreign invaders. Additionally, obesity can lead to resistance to leptin—a hormone produced by fat cells that supports white blood cell production and enhances immune function.

What to Take

Herb and supplement stand-outs for immunity:

  • Ashwagandha, an Ayurvedic herb traditionally used as an adaptogen to combat stress and boost energy, may also enhance immune function by increasing production of certain key players. One recent study suggested that ashwagandha may also help protect against colon cancer.
  • Propolis, a sticky, glue-like substance produced by honeybees and used to construct their hives, is strongly anti-bacterial. In one study, propolis was more effective than an antibiotic mixture against a strain of Enterococcus bacteria.
  • Astragalus, traditionally used in Chinese medicine to treat diabetes and speed healing, also has immune-supportive effects, and can help combat HIV. It’s especially useful in supporting the immune system during chemotherapy, and other studies have suggested that astragalus may also protect against some kinds of cancer.
  • Ganoderma lucidum (reishi mushroom) is a fungus traditionally used in Chinese medicine for health, longevity, and recuperation. Many studies have pointed to the potent immune-supportive effects of reishi mushroom, and more recent research suggests that reishi inhibits tumor growth.
  • Probiotics have a wide range of immune-supportive actions, especially in diarrhea, allergies, eczema and viral infections. Other studies point to their effectiveness in treating irritable bowel syndrome and reducing inflammation.

Olive leaf extract—from the Mediterranean olive tree—is rich in antioxidants and has strong antiviral activities. In one study, olive leaf extract inhibited HIV-1 replication. It’s also been shown to lower blood pressure and reduce LDL cholesterol.

Our Product Picks

SOLGAR Astragalus Root Extract Astragalus, used in traditional Chinese medicine, has immune-supportive effects. This standardized, full-potency astragalus root extract provides naturally occurring flavonoids and polysaccharides. Capsules are vegetarian.

HERO NUTRITIONALS Yummi Bears Organics Immunity Shield This fun-to-take gummy protects kids with natural vitamins E and C, zinc, and immune-boosting herbs. Free of gluten, casein, allergens, and artificial flavors or colors.

IRWIN NATURALS Immuno-Shield maximizes your body’s natural defense system with a blend of antioxidants, herbal extracts, and bioflavonoids that support healthy respiratory function.

TWINLAB Immunity Booster combines beta glucan with arabinogalactan, both clinically shown to have a positive impact on the immune system, plus vitamins C and E and an herbal blend for powerful immune support.

Homeopathic Healing

Homeopathic remedies are safe and can be tailored to individual symptoms. Here are homeopathics for some of the more common ailments your family may face during cold and flu season. Many homeopathic kits are outfitted with several of the following remedies, and each can also be purchased individually.

HEEL Engystol is a safe homeopathic formula designed to support the immune system against the symptoms of flu, including fever, body aches, and chills.

BOIRON Oscillococcinum. Have a tube handy and take at the first sign of flu-like symptoms including headache, body aches, chills, fever, and run-down feeling.

HYLAND’S Flu features a classic combination of six of the most effective homeopathic medicines for easing chills, headaches, fever, soreness and body aches down to your bones. It’s all-natural and safe to take with other medicines.