By: Christopher D. Jensen, PhD, MPH, RD
Supporting and Boosting Your Immune System
Nutrition & Epidemiology Researcher
The fact is that rigorous endurance training and exhausting competitions can temporarily impair your immune system and leave you vulnerable to nagging colds that sap your strength and wreak havoc on your training and competition schedule.
Colds are common after endurance events
Endurance exercise and catching a cold often go hand-in-hand. Researchers following ultra-marathon runners competing in a race in South Africa found that about one-third of the 150 athletes they tracked ended up developing an upper respiratory tract infection within a few weeks of the race. Among athletes competing in the grueling 100-mile Western States Endurance Run, about one in four reported cold symptoms in the two weeks following the event. And in over 1,800 runners competing in a full marathon, almost 13% reported coming down with a cold within a week of the race.
What’s up with the spike in colds post-exercise? The theory is that the physical stress of a heavy bout of endurance exercise increases the circulating concentrations of stress hormones like adrenaline and cortisol. In the short term, these hormones help you meet the immediate physical demands of exercise. But the price paid is a temporary suppression of your immune system — often it’s just enough of a window of opportunity for a head or chest cold to take hold.
So how do you reap the benefits of your training and compete in your events, without short-circuiting your immune system? As it turns out, nutrition may help.
Nutrition Strategies for Supporting Your Immune System
An important strategy when you’re training for or competing in an Ironman triathlon is to ensure that your diet provides all that you need in the way of nutrients and dietary factors to support healthy immune function:
- Adequate protein in the diet is important because critical components of the immune system, such as antibodies, are made up of protein. The protein you eat is digested into amino acids. These amino acid building blocks are then absorbed and repackaged into the types of protein your body needs, including those proteins that support immune function. Protein also provides the amino acid glutamine, which serves as a fuel source for important immune system cells. Having adequate glutamine available helps your immune system launch an appropriate counterattack against pathogens that might otherwise put you under the weather.
- Essential vitamins and minerals are also important. These nutrients support the rapid replication of immune cells that is a critical step in warding off cold bugs and other infectious agents. Eating a wide variety of different foods, including plenty of fruits, vegetables, and grains can help ensure you get the nutrients you need. A case can also be made for a balanced once-a-day type multi-vitamin and -mineral supplement as an extra measure of insurance for consistently getting the essential vitamins and minerals you need to support your immune system.
- Calories are critical, yet many Ironman triathletes spend so much time training that there’s often little time left over to purchase, prepare, and eat the food needed to be their best. Also, some athletes make the mistake of ramping up their training while cutting calories to try to get leaner. Unfortunately, that can be a shortcut to the infirmary. Researchers have found that for endurance athletes, even a few weeks of dieting to lose weight can impair the function of your immune system. To ensure that your immune system stays strong when you’re training hard or competing, definitely avoid dieting. Also, plan ahead and have snacks and meals at the ready so that inadvertent calorie shortfalls don’t occur during periods of heavy exercise.
- Carbohydrate intake not only fuels your muscles, it also seems to play an important role in immune function. Studies show athletes eating low-carbohydrate diets who engage in prolonged strenuous exercise end up with sharp increases in circulating levels of the stress hormones. As stress hormone levels rise, the number and activity of key cells involved in immune function declines. Fortunately, consuming adequate carbs during exercise reduces the rise in stress hormones and seems to help offset their suppressive effect on immune function. Will more carbs translate to fewer colds? No one knows for sure, but it’s well documented that fueling with carbs during exercise delays the onset of fatigue and extends endurance, so the possibility of an added immune system boost makes carbs a no-brainer.
- A little extra vitamin C may help too. In two different studies, runners taking 500–600 mg of vitamin C daily for a few weeks before and a few days after an ultra-marathon had lower rates of upper respiratory tract infections compared to those taking placebo pills without vitamin C. Unfortunately, other researchers weren’t able to replicate these findings, so definitive proof of benefit is lacking. Nonetheless, taking a daily 500 mg vitamin C supplement or boosting your vitamin C intake from fruits and fruit juices during heavy periods of training and for a few weeks before and after triathlon competitions may be a measure worth considering.
- Finally, the live and active cultures found in yogurt and some other products may be a helpful addition to your diet. Some of these beneficial microflora, often referred to as probiotics, have been studied and shown to support a healthy immune system. And, at the very least yogurt is a good source of protein for muscle tissue repair and carbs for muscle refueling.
Cold Prevention Checklist
To summarize, do the following to help avoid the sniffles during heavy training or tough Ironman Triathlon competitions:
- Make sure not to compound the physical demands of heavy training or competing by scrimping on calories
- Consume plenty of carbs when training and competing: they not only increase endurance, they may reduce the immune system suppression associated with strenuous endurance exercise
- Ensure that your protein intake is adequate so that your body has the amino acid building blocks to make the proteins you need for healthy immune function and the amino acid glutamine to fuel key immune system cells that defend against attack
- Eat from a wide variety of foods and consider a daily multi-vitamin and -mineral supplement to ensure that your diet always has an adequate supply of the nutrients needed to support immune function
- Take in a little extra vitamin C during periods of heavy training and a week or two before and after competitions, as this may give your immune system an added boost
- Put yogurt, yogurt drinks or other products with certain active cultures on your grocery list. These beneficial microbes may help support keeping your immune system healthy.
Topics: General, Recovery, Carbs, Research, Probiotics