6 Delicious Ways to Boost Your Immunity

Don't get sick this winter! Stock up on the below suggestions to keep training hard and recovering fast.

by Kimberly Mueller, MS, RD, CSSD

In order to maintain your health and perform well throughout the duration of racing season, it’s essential to not only fuel your muscles and energy systems but your immune system as well. While the cycling lifestyle generally helps enhance immune resistance, some studies have shown long periods of exhaustive exercise—aka training—to have the opposite effect, leaving cyclists to suffer from slow recovery times, frequent infection, and poor performance.

Fortunately, being proactive with your nutrition, as most cyclists are, will help keep your body at its peak when prepping for swimming, biking, and running. And guess what? They all taste really, really good, too.

1. Eat a rainbow every day

Each meal should contain foods providing plenty of color. No meat and grain lovers, red and beige don't count here. Fruits and vegetables are loaded with plant-based nutrients called phytonutrients and antioxidants, which help protect our immune cells from harmful oxygen molecules called free radicals.

Studies have found that individuals consuming at least five servings of fruits and vegetables each day are able to produce more natural killer T-cells (the type that destroy the pathogen) and virus-killing lymphocytes, ultimately helping to reduce the incidence of infection by 50 percent each year compared to those not so keen on color in their diet.

2. Don't fear garlic and onion

Garlic and onion contain the compound allyl sulfide, which as been shown to increase levels of infection-fighting white blood cells, boost natural killer T-cell activity, and enhance the efficiency of antibody production, thereby helping to fight off the common cold and other infections. Furthermore, laboratory studies have demonstrated that sulfur compounds within garlic help regulate inflammation by inhibiting the activity of inflammatory enzymes. Preliminary evidence, primarily from animal studies using aged garlic extract, suggests that this may benefit the health of the musculoskeletal system during training.

For optimal immune and anti-inflammatory support, consume one chopped garlic clove daily or use a standardized extract at a dose of 600-1200 mg split into three doses daily and/or eat one medium onion each day. Just remember to bring the breath mints!

3. Boost your zinc intake

One of the most common nutritional deficiencies among American adults, especially vegetarians, is zinc, which is unfortunate for the immune system. Zinc not only increases the production of white blood cells, which help recognize and destroy invading bacteria and viruses, it also helps enhance killer T-cell activity which helps reduce risk of cancer and other infection.

Zinc is found extensively in beef products; a mere 3-ounce serving contains 30 percent of the Daily Value for zinc. For vegetarians and non-beef eaters, zinc can also be found in oysters, fortified cereals, crab, turkey, pork, yogurt, and beans. While the current Recommended Daily Allowance for zinc in adult men and women is 11 mg and 8 mg respectively, many experts believe an increase in intake to 25-30mg per day is warranted during heavy training cycles as means to better support immune functionality.

4. Fuel with carbohydrates during and after hard training sessions

Immune suppression has been noted in the two-hour period immediately following prolonged and/or intense training. This is in part due to elevated levels of the stress hormone cortisol and a corresponding drop in lymphocyte production and T-cell activity.

Dr. David Niemann, a pioneer in the study of exercise immunology, has shown consumption of carbohydrate during and immediately after training to reduce cortisol levels and maintain lymphocyte production, thereby helping prevent infection. Thus, during heavy training, a carbohydrate consumption of 30 to 90 grams per hour is recommended. In addition, 0.50 to 0.75 grams of carbohydrate per pound of (lean) body weight should be consumed as quickly as possible post-training.

5. Fear not fungi

Mushrooms, especially shiitake, reishi, and maitake mushrooms are a good source of beta glucan, a complex chain of glucose molecules that has shown promise in increasing the production and activity of white blood cells, allowing them to aggressively destroy pathogens. Some studies have shown an immune benefit with a mere half-cup serving daily.

As an alternative, a daily intake of 100 to 500mg of supplemental beta glucan (derived from mushrooms or yeast) has been shown to be effective for enhanced immune function during heavy training cycles.

6. Add some culture to your diet

Consuming yogurt products that contain active cultures (called probiotics) seem to increase the amount of friendly bacteria that line the intestinal wall, helping to fight off germs that would otherwise enter and cause infection. In fact, several studies have found that daily consumption of just one cup of yogurt containing probiotics helps to reduce the chance of contracting the common cold throughout the year. A higher dose, aka more probiotics, seems to further protect the body against viruses.

These same benefits can be obtained by drinking a fermented milk drink called kefir. When possible, try to buy yogurt that is less than a week old to ensure reaping the most benefit from the active cultures. Not a fan of yogurt? Consuming a probiotic supplement with 250 million to 20 billion organisms (the more the better), containing the lactobacillus strain and in an enteric coating will benefit both the immune system and intestinal health during high volume training.

Kim Mueller, MS, RD, CSSD, is a Board Certified Sport Dietitian and elite endurance athlete providing custom menu planning, nutrition coaching, and detailed race nutrition guidance with her company Fuel-Factor.com.