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How to Strengthen Your Immune System, According to Experts

In a recent GU Energy Lab nutrition happy hour, we learned how runners can stay healthy this fall and winter.

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With nearly all of our interactions happening online lately, a nice added bonus has been the abundance of webinars and panel discussions that runners can access at home. These free learning opportunities are connecting people who may have not otherwise had the chance before. We dropped into one of these webinars, hosted by GU Energy Lab, to learn a little bit about how to strengthen your immune system. 

The September 10 discussion was moderated by GU’s nutrition and research performance manager, Roxanne Vogel. Ultrarunner and Inside Tracker sales manager Jonathan Levitt and Greg Grosicki, director of Georgia Southern University’s exercise physiology lab, joined as the panel of experts. 

Grosicki started off by giving a brief look at how the immune system works and how, as we train hard, we wear it down. “I think that really gives us reason to care about immune health as athletes,” he says. With the coronavirus still spreading, immune health is top of mind, but coming into cold and flu season as well, this really is an ideal time to learn about how our body works to keep us healthy and what more we can do. Here are five new things we learned from Grosicki and Levitt.

The immune system has two branches of defense.

The first is the innate immune system. It is our first line of defense against viruses and bacteria and includes physical barriers like our skin and mucus in the eyes, nose, and gastrointestinal tract. “If by chance, one of these foreign invaders does make its way in,” says Grosicki, “then we have this initial cellular defense, made up of white blood cells, which are also known as leukocytes.” 

When the innate immune system doesn’t work, the adaptive immune system takes over. “This will act over days or possibly weeks of being sick,” he says. All of that defense system happens on the cellular level with white blood cells like leukocytes and lymphocytes.

The immune system has a high metabolic rate.

Eating enough food is important to keep improving as a runner, but it’s especially important for the immune system. “Immune cells in particular have among the highest metabolic rates of cells in our body, so they’re constantly needing nutrients,” says Grosicki. The immune cells need a healthy and diverse array of macro and micronutrients every day. The food we eat is “really fueling these cells in our immune system to fight against pathogens,” he says.  

The gut, sleep, and immune health are all intertwined.

We know that getting a good night’s sleep helps to keep us from getting sick, but did you know your gut health affects how you sleep? All three are closely related. 

Vogel points out that the immune system goes into overdrive, doing its best work while we are sleeping. “That’s why a lot of times your body temperature might go higher at night or you wake up and you feel like you might be a little more sick in the morning,” she says. And that is partly because it’s not fighting with the high energy needs of waking life. 

In turn, gut health can affect sleep. In this study, published by Grosicki’s lab in the Journal of Sleep Medicine, they found that even young, healthy individuals suffered from sleep problems when their gut microbiome was not in an ideal state. Grosicki also cited research, mostly done in animal models, that found that the fatty acid butyrate, which is produced by healthy gut bacteria, could improve REM sleep almost immediately. Butyrate is produced when your diet is full of fiber. “We get the right bacteria, we give them the right substrate to build butyrate, we increase butyrate, we sleep better, we make our gut healthier, and we fortify our immune system that way,” he says. 

Poor gut health can also directly affect our immune system, besides just through sleep. “We know that immune cells are metabolically active, and thus, if we have some sort of dysregulation in our gut that’s influencing our ability to digest and absorb the important nutrients that we’re eating, and get those into our body, that’s a huge problem,” says Grosicki.  

Certain foods build your immune system.

Besides just fiber, which is very beneficial for gut health, Levitt lists foods rich in probiotics like kimchi, yogurt, sauerkraut, miso, and tempeh. 

To get more essential zinc, Levitt recommends oysters or any type of shellfish, as well as pumpkin seeds, sesame seeds, spinach, dark chocolate, and walnuts. “All of these are good options and also foods we recommend for many other reasons, so you’re doing yourself a service if you’re eating nuts and seeds or spinach or shellfish,” he says.  

As for vitamin D, “things like sunlight, fatty fish, egg yolks, mushrooms, and fortified milk can help boost that up or support a healthy level of that,” he says. 

High doses of vitamin C can negatively impact your training.

As the panelists point out, vitamin C is pretty much what comes to mind when you think about nutrition for immune health. But too much can actually undo your training because of its high levels of antioxidants. “Many people can and should get their vitamin C through food,” says Levitt. “Fruits and vegetables are a great source.”

Grosicki recommends only taking a vitamin C supplement if you are going to be traveling, if you’ve been around someone who is sick, or if you’re stressed. Levitt notes that if you are already sick and taking a supplement, it shouldn’t bother your training because you shouldn’t be running at that point anyway. 

If you want to catch the rest of the GU Energy Lab’s ABC’s of Nutrition, they will continue to run on Thursday nights for the next six weeks. Rewatch this one here.

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