Six Nutritional Keys to Optimizing Immune Function
By: Kimberly Mueller, MS, RD, CSSD
In order to maintain health and perform well throughout the duration of a racing season, it’s essential to properly fuel the immune system. While the runner lifestyle is generally favorable for the immune system, helping enhance immune resistance, some studies have shown long periods of exhaustive exercise, common during marathon training, to heed the opposite effect, leaving the runner suffering from slow recovery times, frequent infection, and poor performance. Fortunately, being proactive on the nutrition front will help keep your immune system and overall performance running at peak when preparing for different races. In this article, I offer 6 keys to optimizing immune function.
1. Eat a rainbow of color every day
Each meal plate should contain foods providing plenty of color, fruits and vegetables and particularly those with a deep hue. 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 5 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% each year compared to those not so keen on color in their diet.
2. Strengthen the flavor of your next meal with garlic and onion
Garlic and onion contain the common 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 1 chopped garlic clove daily or use a standardized extract at a dose of 600-1200 mg split into 3 doses daily and/or eat 1 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, but 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% of the Daily Value for zinc. For vegetarians and non-beef eaters, zinc can also be found in oysters, fortified cereals, crab, turkey, pork, yogurts, and beans. While the current Recommended Daily Allowance for zinc in adult men and women stands at 11 mg and 8 mg respectively, many experts believe an increase in intake to 25-30mg/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 2-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 long runs and harder workouts, a carbohydrate consumption of 30-60 grams per hour is recommended with doses up to 90 grams per hour being of potential benefit for those runners training for ultra-distance events. In addition, 0.50-0.75 gram of carbohydrate per pound of (lean) body weight should be consumed as quickly as possible post-training.
5. Don’t shy away from fungus
Mushrooms, especially shiitake, reishi, and maitaki mushrooms are a good source of beta glucan, which is 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 ½ cup serving consumed daily. As an alternative, a daily intake of 100-500mg 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 a mere cup of yogurt containing probiotics help to reduce the incidence of the common cold throughout the year. A higher dose, aka more probiotics, seems to further protect the body against viruses. The same benefits can be obtained by drinking a fermented milk drink called kefir. When possible, try to buy/eat 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 optimally benefit both immune functionality and intestinal health during high volume training.
Kimberly Mueller is a Registered Dietitian, Board Certified Specialist in Sports Dietetics, elite runner, author of The Athlete’s Guide to Sports Supplements (Human Kinetics, 2013), and owner of Fuel Factor (www.Fuel-Factor.com). She has enjoyed helping fellow runners dial in their nutrition and training for optimal health and performance for over 15 years. Contact her at kim@Fuel-Factor.com