The following is brought to you by professional nutrition coach Georgie Fear, a Registered Dietitian and former rower, marathoner and ultrarunner, who recently co-authored the Racing Weight Cookbook. For more on Fear and her nutrition tips and recipes, visit askgeorgie.com.
In the fall, training volume for winter athletes is generally at its highest. As the season approaches, athletes want to be strong, fast, and lean, and putting in the hours to train is essential. It’s also critical for good nutrition to be a part of your routine, so that you can ward off illness. After all, getting sick can cost an athlete days or even weeks of critical workouts, and competing while fighting a bug is unlikely to lead to your best performance.
Should you load up on Vitamin C? Drink gallon of echinacea tea? How can you give yourself the best odds of fighting off infections this winter?
Read on for evidence-based nutrition tips to keep your immune system as strong as can be while you hit your peak training volume and performance.
Carbohydrates During Training
Intense and high-volume exercise is known to result in immune system suppression. Training stimulates the release of cortisol and other stress hormones, which decrease the synthesis of immunoglobulins and the proliferation of white blood cells. Consuming carbohydrates while training dampens the rise in cortisol and other stress hormones associated with intense exercise. It also appears to limit exercise-induced immune suppression.
To keep your immune working full-throttle while you’re training hard, consume 30-60 grams of carbohydrate per hour while training, instead of waiting until after your workout to begin refueling.
Consume Enough Protein and Calories
Diets which are too low in protein have been shown to impair immunity by decreasing phagocyte and T-cell function. There is evidence that hard-training athletes should consume at least 15% calories from protein to maintain immune function. Rather than breaking out a calculator to ensure that you get enough, a foolproof way is to include at least one high-protein food each time you eat, such as eggs, meat, poultry, seafood, protein powder, cheese, yogurt, soy, or beans.
When training volume is high, it becomes a challenge for some athletes to eat enough calories, making them more vulnerable to glycogen depletion, overtraining syndrome, hormone disturbances and immunosuppression. Liquid calories can help boost total energy intake, and increasing carbohydrate intake before, during and after training sessions can help maintain intramuscular glycogen.
Vitamins and Minerals
Many vitamins and minerals play a role in keeping your immune system strong. Vitamin B12 (found in beef, turkey and seafood), and folic acid (found in spinach and avocado) are needed for the synthesis of red and white blood cells. Deficiencies in copper, selenium, or iron weaken the immune system by impairing macrophage production, natural killer cell activity, and antibody formation. Whole grains, beans, nuts and seeds are rich in vitamins and minerals, and make excellent staples to add into your meals. If you need some meal ideas, there’s more than 100 dietitian developed and athlete-approved recipes in the Racing Weight Cookbook.
What About Supplements?
If I could make only one supplement recommendation to winter athletes to stay healthy, it would be to supplement vitamin D, especially in the winter months. The amount of circulating vitamin D in an athlete’s blood correlates not only with the number of times they get sick each year but also with symptom severity and duration of illness. In other words, getting enough vitamin D benefits you three ways: you’re less likely to get sick, and if you do get a cold, it’s milder and shorter-lived.
Vitamin D is very sparse in natural food sources, and even in countries where milk is fortified with vitamin D it is at a low enough level that sub-optimal vitamin D intake remains widespread. Very little of this vitamin is diet-derived; almost all of the vitamin D in the human body is synthesized in the skin in response to UV exposure. For those in warm, tropical climates where the sun shines abundantly, synthesizing vitamin D year-round is no problem, but for much of the year it is impossible to synthesize ANY vitamin D north of 35 degrees latitude, due to the angle of the sun’s rays. That means across most of the United States and all of Canada, you couldn’t synthesize enough vitamin D even if you trained outdoors every day naked (though it might make your social life interesting). So taking a vitamin D supplement of at least 2,000 IU (International units) and up to 5,000 IU is paramount during the winter.
Supplementing with Vitamins C and E has been shown in some studies to reduce the incidence of upper respiratory tract infections in athletes, but other trials have observed no effect, so the evidence is not clear if supplementing these nutrients is definitively worth it. It’s unlikely to do any harm however.
Dietary zinc plays an important role in thymic function, lymphocyte development, and resistance to infections. Inadequate dietary zinc lessens immunity, but excessive zinc intake (as found in high dose supplements) also damages the immune system. Thus, mega-doses of zinc are not recommended. Research supports supplementing 10-20 mg per day of zinc, especially for vegetarians, who naturally consume less zinc. (For reference, the megadoses which negatively impacted the immune system were more than ten times this amount, totaling 300 mg per day).
Most of the athletes I work with choose to take a multivitamin in addition to choosing a varied diet based on whole, nutrient rich foods. This can be a good way to make sure that your vitamin and mineral bases are covered, but is by no means license to ignore your food intake. Whole, unprocessed foods are still the cornerstone of a high performance diet. Rumor has it that traveling on the World Cup circuit means that fresh vegetables are hard to come by in some places, but if you have a daily multivitamin on hand, at least you know most of your micronutrient needs will be met.
What to Do
In summary, to avoid immune system suppression associated with peak training volume:
- Drink a carbohydrate-containing beverage during all intense workouts, aiming for 30-60 grams of carbohydrate per hour of exercise.
- Follow up training with a recovery meal as soon as possible, containing a 3:1 or 4:1 ratio of carbohydrates to protein.
- Eat nutrient rich foods such as whole grains, lean proteins, nuts and seeds, and a colorful array of vegetables and fruit.
- Eat enough to maintain your weight, and include a protein-rich food at each meal
- Take a multivitamin providing about 100% of the recommended daily intake of vitamins and minerals, and supplement with additional Vitamin D during the winter months (2000-5000 IU per day).
- Check out the Racing Weight Cookbook for delicious recipes and more guidance on getting enough carbohydrates, proteins and nutrients for optimal performance and body composition.
Georgie Fear is a professional nutrition coach whose advice is sought after by athletes ranging from NCAA standouts to Olympic gold medalists. A Registered Dietitian and former rower, marathoner and ultrarunner, Georgie has been helping clients get leaner, healthier and faster since 2005. Her writing and recipes appear at www.AskGeorgie.com.