Nutrition and Immunity: How To Stay Healthy

Keep your immune system in top-notch shape so you can enjoy outdoor training year round.

The status of your immune system might not be the first thing you think about when you get out of bed in the morning, unless you are feeling sick. Let’s face it; if you can’t breathe, you can’t run.

I don’t know about you, but I’d rather stick to outdoor training, no matter what the weather. But the stress of training, layered on top every day life does increase the risk of coming down with a bad bug. Can nutrition make a difference? You bet. Here’s a quick recap of the “principals of immunity” offered by David Nieman, PhD, FACSM, Department of Health and Exercise Science, Appalachian State University at the annual Gatorade Sports Science Conference in Chicago last July.

Principle #1: Almost all nutrients in the diet play a crucial role in maintaining an “optimal” immune system.

David Nieman has been studying the effects of exercise and the immune system for over 30 years. An avid marathon competitor himself, he “walks” his talk. “I got interested in the effects of exercise on the immune system,” he explained to the audience at the GSSI conference. “When I saw that many of my students got sick shortly after completing a marathon, which was part of their final exam for the semester.” That observation led to a lifelong interest in looking at the link between exercise, nutrition, and the immune system. Nieman’s research has shown that in healthy people, with a healthy immune system, it is pretty much impossible to “boost” protection. Neither zinc, nor vitamin C, nor extra doses of Echinacea seem to create “super immunity.” Contrary to what advertisements claim, the magic immune boosting bullet has yet to be discovered. According to Nieman, eating a balanced, healthy diet that provides a variety of sources of nutrients from natural, whole foods seem to be the best bet for optimizing immune system function.

Principle #2: Deficient (and sometimes excessive) intakes of energy and nutrients can have negative consequences on immune status.

We sometimes forget that our bodies normally host a variety of “bugs” or pathogens, that aren’t good for us. Unless we upset the delicate balance between the “good” guys and the “bad” guys, the “good” guys usually prevail. Research has shown that the biggest risk to the immune system is a severe, prolonged deficiency in protein and calories, which is not something most Americans have a problem with. But there are circumstances when athletes can put themselves at risk: chronic calorie deficit due to high training volumes does tip the balance in favor of the “bad” guys. Add that to a nutrient poor diet and you just may come down with a cold.

Principle #3:  Advanced supplements may prove useful in countering immune suppression for healthy adults during periods of unusual physical and mental stress.

Sometimes athletes have the attitude that if some is good, more is better. That’s risky reasoning, according to Nieman, and here’s why. Take vitamin E for example. Everybody takes it with their morning coffee, after all, it might help, and it won’t hurt. Or could it?  In a double-blind, randomized study conducted by Nieman’s research team where vitamin E supplements (800 IU) were given to competitors for two months prior to the Kona Triathlon World Championships in Hawaii, he found alarming results. Athletes who were taking vitamin E supplements had the highest level of interleukin-6 (a marker of inflammation) ever recorded. The vitamin E had actually acted as a pro-oxidant, not an antioxidant during the race.

Other studies where a double-blinded, randomized design was used have failed to support earlier studies that suggested that high doses of zinc or vitamin C supplements could improve the strength of a healthy immune system or reduce the risk of getting sick. Nieman’s research from the 1987 L.A. Marathon showed that 1 out of 7 competitors came down with a respiratory infection during the week following the marathon. It appears that moderate exercise of about 45 minutes, actually enhances the immune system, but intense exercise over 90 minutes stresses the immune system, and it can remain depressed for 1 to 3 days afterwards. There are some nutritional countermeasures an athlete can take to minimize this immune depression. First, take carbohydrate feedings at regular intervals during exercise, about 30 – 60 grams, starting after the first half an hour of exercise. Carbohydrates dramatically reduce the rise in stress hormones cortisol and epinephrine. Second, because the immune system is so diverse, Nieman suggests it may be helpful to consume a “cocktail” of nutrients such as glutamine, arginine, and other vitamins. Although studies have looked at single nutrients and have not shown them to be effective individually.

Food and Immune Function

Although the jury is still out on humans, animal research suggests there are certain components in foods that can strengthen the immune system when it’s under stress. Nothing fancy or expensive here, just try some of these common foods.

Oatmeal (whole oats) is an excellent source of beta-glucan. Beta-glucans in mice have been shown to offset exercise-induced immune depression and decrease the risk of respiratory tract infections. Can’t stomach oatmeal every day? Try Cheerios, or any cereal that contains whole grains.

Quercetin is the second food component that looks promising. Quercetin is a phytochemical found in cranberries, blueberries, apples, broccoli, onions, and red wine.

Tea is the beverage to be sipping following a hard ski or snowshoe. Tea extracts contain the amino acid L-theanine, antioxidants (epigallocatechin gallate), and polyphenols. If you can’t pronounce these nutrients, not to worry, just drink it.


Dr. Nieman’s Prevention Strategies for Staying Well

Nutrition is not the only factor affecting the immune system.  Here are some other suggestions:

1.  Eat a well balanced diet to keep vitamin and mineral pools in the body at optimal levels.

2.  Use carbohydrate (1 liter/hour) before, during, and after prolonged, intense exercise.

3.  Sleep on a regular schedule.

4.  Avoid rapid weight loss.

5.  Avoid overtraining and keep other life stresses to a minimum.

6.  Avoid putting the hands to the eyes and nose (a major route of inoculation).

7.  Before important events, avoid sick people and large crowds as much as possible.

Originally published in January 2015 Issue.
Written by Donna Marlor, MA, BSN, RD