Unless you live in a plastic bubble, you can’t seal yourself away from all germs in life. They’re everywhere—especially this time of year. Your best bet to stay healthy is to strengthen your immune system so it can defeat any microscopic invaders before they lay siege.
But if you took all the immune boosters recommended by magazines, books, and Mom, you’d not only empty your pocketbook, but you’d likely harm your health too. “Don’t get trapped into thinking you want to boost your immunity as much as possible,” says Mark Moyad, MD, director of preventive and alternative medicine at the University of Michigan Medical Center. “Allergies and autoimmune diseases are examples of a hyperreactive immune system.” Moyad suggests taking most immune-bolstering supplements during cold season but then scaling back for the rest of the year (with the exception of multivitamins and vitamin D3). But the question remains: Which of the myriad supplements and strategies out there really work? We asked our experts, and you’ll be surprised at how simple and effective their top picks are.
Shore up your defenses. “Lifestyle is the best tool,” says Mary Saunders, LAc, founder of Boulder Community Acupuncture in Boulder, Colorado. You’ve heard this a million times, but for good reason. Getting eight hours of sleep a night, reducing stress, exercising, staying hydrated, and eating mostly produce, whole grains, unsaturated fats, and lean protein gives your body the raw nutrients and energy it needs to manufacture immune cells. These healthy habits also decrease levels of the stress hormone cortisol—which can suppress immunity in high amounts—and balance the body’s alkalinity ratio. “Pathogens thrive in acidic environments,” says Saunders. “If you keep your body alkaline, you’re more resistant to infection.” Coffee, alcohol, sugar, and hard cheeses increase acidity, so limit your intake. For extra help getting your fruits and veggies, Saunders recommends green drinks—specifically Designs for Health’s PaleoGreens (available only through health practitioners), ProGreens by the Allergy Research Group, and New Chapter’s Berry Green—that contain at least four servings of vegetables.
Lose an inch. Along with lowering your risk of heart disease, “losing just one inch from around your waist boosts immunity tremendously,” Moyad says. It does this partly by decreasing inflammation. Normally, during an acute illness or infection, white blood cells release inflammatory chemicals that fight bacteria and viruses. In this case, inflammation is a good thing. But excess belly fat triggers the release of those inflammatory compounds even in the absence of a threat. This chronic, low-level inflammation “throws off the immune system, so it starts treating the body itself as a problem,” Moyad says. This raises the risk of everything from diabetes to the common cold. A good trick for dropping the spare tire: Buy a pedometer, and take at least 10,000 steps a day.
Rinse, gargle, repeat. Rinsing your nasal passages and throat with saline water is so simple you may say “duh,” but in reality, this is one of the most powerful—and overlooked—actions out there. Since pathogens enter through the nose, mouth, and eyes, saline rinses wash away the li’l buggers before they can infect other tissues. What’s more, in a 2005 Japanese study, people who gargled daily even with just plain water had significantly fewer respiratory infections. Moyad recommends rinsing your nose with a neti pot and gargling with salt water once a day. If you feel a cold sneaking up, increase that to three times daily. Simply Saline makes super-convenient gargle packets and nasal sprays.
Embrace probiotics. “Most people don’t connect their GI tract with immune health, but in fact, it plays a major role in protecting our bodies from infection,” says Jeffrey Bland, PhD, cofounder of Bastyr University and the Institute for Functional Medicine. The good bacteria, such as Lactobacillus acidophilus and Bifidobacterium lactis, in probiotics balance out the bad, illness-causing bacteria in your gut, decreasing the chance of infection. You can get probiotics through supplements (follow the label’s recommended dosage) or by eating foods with live and active cultures: yogurt, raw sauerkraut, kefir, and fermented soy foods.
Soak up your D. You’ve probably heard a lot about this nutrient, since growing research links vitamin D deficiency to myriad diseases, including diabetes, cancer, multiple sclerosis, and more. When it comes to preventing colds, strong evidence suggests vitamin D can crank up your immune defenses against intruders, though how the nutrient works remains unclear. In a 2009 Archives of Internal Medicine study involving nearly 19,000 people, researchers found that those with low levels of vitamin D were 40 percent more likely to have had a recent respiratory infection. “One theory is that vitamin D in the blood stimulates the body’s production of a naturally occurring antimicrobial called cathelicidin,” says Bland. Cathelicidin either destroys or inhibits invading microorganisms, such as bacteria, viruses, and funguses. Shoot for 1,000 IU each day of vitamin D3. Since a 2009 University of Colorado study suggests that nearly three-fourths of the population is vitamin D deficient, you may want to ask your doctor for a blood test that can determine D levels.
Take two: vitamin C plus honey. Moyad calls this combo an immunity “double shot,” a one-two punch to strengthen your system. The extensively researched vitamin C amps up the production of infection-fighting white blood cells, while honey has proven antimicrobial and immune-fortifying properties. “From recent research, honey looks just as exciting for preventing colds as for treating them,” says Moyad, though scientists are still studying how it works. All honeys have these health benefits, but darker honeys such as buckwheat (made from buckwheat pollen) tend to have a greater antimicrobial effect and more antioxidants, says Moyad. During flu season, take 500 to 1,000 mg of vitamin C once daily (people with sensitive stomachs may prefer the nonacidic calcium ascorbate and Ester-C varieties) and 1 teaspoon honey three times daily.
Go green with spirulina. This blue-green algae is a nutritional powerhouse, packed with protein, vitamin B12, iron, beta-carotene, and other antioxidants. A recent review in Evidence-Based Complementary and Alternative Medicine shows that spirulina wards off infection by upping levels of bacteria-killing immunoglobulin-A (IgA), which Moyad describes as “the principal antibodies that cruise along the mouth and nasal passages where cold and flu enter. Essentially, spirulina increases the size of your defense military.” A standard dose is 1 gram daily, taken either as a tablet or powder. Saunders cautions that spirulina can be very stimulating for some people. “If you notice agitation or trouble sleeping, stop immediately.”
Make room for mushrooms. “Medicinal mushrooms, including the reishi, maitake, and shiitake varieties, have been valued for their immunostimulating properties for centuries,” says Bland. They contain beta-glucans, complex carbohydrates that boost the activity of immune cells—specifically macrophages and natural killer cells, both of which attack the germs that can make you sick. Mushrooms also have powerful antimicrobial (bacteria-killing), anti-inflammatory, and antioxidant properties. Another mushroom product that can dramatically increase natural killer cell activity is AHCC, a hybridized mushroom extract. A 2006 study published in The Journal of Nutrition found that giving mice AHCC for a week before and then throughout influenza exposure decreased the severity of infection and recovery time. But since “mushroom extracts are very potent, ask your natural doc which variety and dose you need,” says Bland.
Repair your immune system with NAC and larch. These two supplements can help restore the severely depressed immune systems found in people who get sick more than two to three times a year. N-acetylcysteine (NAC), an amino-acid derivative, is converted in your body into glutathione, a key antioxidant that does several things: It neutralizes damaging free radicals; strengthens cell membranes, making them more resistant to pathogen attack; and detoxifies harmful chemicals in the liver. NAC also helps prevent and heal those annoying hacking coughs by breaking down mucus in the lungs. Meanwhile, larch (Larix) contains arabinogalactan, a compound that stimulates white blood cells to seek out and destroy bacteria and viruses. When people who are often ill combine larch with healthy lifestyle changes, “I’ve noticed they get sick less frequently and have less severe symptoms,” Saunders says. Typical dosages are 1,000 mg of NAC and 1 teaspoon of larch per day (for larch tablets, follow the dosage instructions on the supplement label).
Pop a multivitamin. This will cover your nutritional bases, ensuring you get enough immune-strengthening vitamins and minerals—particularly zinc. Bland says zinc “spurs the production of immune cells and promotes the integrity of the gastrointestinal lining,” keeping pathogens in your gut from crossing into your bloodstream. “Deficiencies have been associated with a depressed immune system and increased susceptibility to infection.” Still, all you need is 10 to 20 mg of zinc daily. Overdosing can be toxic, so Moyad doesn’t usually recommend supplementing solely with zinc for cold prevention or using topical, zinc-containing cold products like Zicam. In fact, in June, the FDA advised people not to use Zicam Cold Remedy Nasal Gel or Swabs after more than 130 reports of people losing their sense of smell.