Saint Louis University

BLOG: For Athletes: Boost Immune Function with Nutrition

Author: Liz Earhart
Published: Wednesday, November 7, 2012

Gatorade, Powerade and other popular sports drinks are heavily advertised as the preferred product to refuel the body with after sports performance or exercise, but are these sports drinks really the optimal choice for athletes to consume in regards to rebuilding muscle and refueling storage systems throughout the body post-workout? The avid users of these products may say “yes”, but current research literature states differently. Chocolate milk is the new product of choice given its result on post-game or performance recovery.

Saint Louis University Dietetic Intern athletes
Source: ambro/

The changing leaves and brisk weather bring with them the dreaded cold and flu season. One of the last things any college athlete wants to is to get sick during season. I finished up my community rotation at the SLU Athletic Department, and one of the requirements for this particular rotation was to write an evidence-based article relevant to college athletes. Thinking about what would be the most relevant nutrition topic to share with college athletes, I thought about the fact that fall is here and winter is going to come before we know it. As training intensity increases for college athletes, practices become longer, and competition becomes more frequent, an athlete’s risk of getting sick increases.

Research has shown that there is a close relationship between exercise and immune function. Each time heavy exercise is performed, stress hormones increase and inflammation occurs. This results in suppression of the body’s immune function and therefore, the ability to fight off colds, the flu, infection and injury. The immune system can be suppressed for only a few hours or even up to 72 hours after exercise. This varies from person-to-person and overall immune function is unique to each athlete. For this reason, getting a good balance of nutrition at all times, and particularly after exercise, is so important for college athletes.

Fuel to Boost Immune Function

Eating a well-balanced diet and staying hydrated should be the first line of defense after a tough workout or competition for athletes.

  • Eat enough carbohydrate before, during and after exercise to help offset the immunosuppressive effects of exercise. If working out more than 2-3 hours per day for 5-6 days/week (or at a high intensity for less time), 55-65% of calories should come from carbohydrates.
  • Protein will help to repair damage and support immune function. Athletes typically need 1.0 –
  • 2.0 g/kg of body weight, depending on the intensity of exercise.
  • Obtain vitamins & minerals from food sources when possible. Here are just a few that may support immune function:
  • Vitamin C – shown to improve immune health and fight off upper respiratory tract infections
  • Vitamin E – antioxidant that has been shown to reduce oxidative damage caused by exercise, which can negatively impact the immune system
  • Vitamin D – new evidence shows that vitamin D may help in activating the immune response
  • Zinc – known to play a role in several aspects of immunity including skin barrier functions and the development of lymphocytes

Food recommendations from the Academy of Nutrition and Dietetics: Sports, Cardiovascular and Wellness Nutrition Group to enhance immune health:

Saint Louis University Dietetic Intern athletes
Source: chainat/
  • Complex Carbohydrates: 100% whole wheat bread, pasta, brown rice, oats, other whole grains, fruits and vegetables.
  • Fruits rich in antioxidants: oranges, grapefruit, strawberries, blueberries, raspberries, red apples, red grapes
  • Vegetables rich in antioxidants: spinach, broccoli, carrots, bell peppers, asparagus, onions and sweet potatoes
  • Protein: lean chicken, turkey, fish, beef, dairy, eggs and egg whites, beans, soy foods
  • Omega-3 fatty acids: Salmon and other cold-water fish, nuts, seeds, olive oil
  • Vitamin D: Seafood (salmon, tuna, etc.), fortified foods (milk, orange juice, tofu, soy beverages, some cereals), eggs
  • Zinc-rich foods: Fortified cereals, peanuts, seeds (pumpkin and squash), dark chocolate, red meats
  • Probiotics: Found in low-fat or fat-free yogurt (or try Greek yogurt for additional protein)

What about supplements?

It is recommended that athletes try to obtain most of their dietary needs from food soures. This includes incorporating many of the immune-boosting foods every day. It can be difficult for college athletes to meet these needs through food because calorie needs can be much higher than most college students.

Supplementing vitamins and minerals with a simple multi-vitamin may be enough to meet needs, but it is important to consult a registered dietitian or team physician. It is important to note that supplementing beyond the daily recommended amount has not been shown to have any additional health benefits and may even be toxic. Adding protein sources through approved protein powders and supplements are considered appropriate methods of obtaining enough protein in the diet.

Make your own Immune-boosting smoothie:

Combine your favorite smoothie ingredients with immune-boosting function. Here are some ideas to try:

Saint Louis University Dietetic Intern athletes
Source: zirconicusso/
  • 6 oz. Low-fat or fat free Greek or traditional yogurt
  • 1/2 cup Almond milk or soy milk for vitamin E and calcium
  • 1 scoop Protein powder for added protein (any flavor you like, but vanilla works in most recipes)
  • 1 cup Berries, Oranges, Apples, Bananas, or any of your favorite fruits
  • 1 cup Spinach and/or Kale (Don’t be turned off by the color of the smoothie. It tastes great!)
  • 1 Tbsp Chia seeds for anti-inflammatory, omega-3 fats and fiber

These nutrition tips for supporting immune function do not necessarily just apply to athletes. We can all benefit from increasing immune-boosting foods in our diet, especially as dietetic interns. We may not be college athletes (at least not any more if we were), but with any exercise and training, rotations, and loads of work, our immune systems could definitely use a pick-me-up!

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