Immune system needs balance: Exercise, rest, sound GI tract, emotional well-being contribute to our bodies' immunity

By Dr. Eric Potter, Sanctuary Functional Medicine  ·  Jan 25, 2021

Second in a series.

Every structure and system require a foundation on which to stand.

The immune system requires a balance of exertion, rest, GI function, and emotional stability as a foundation to both train it and maintain it.

Science supports and guides this foundational approach, resulting in a better path than simply piling reinforcements without building a foundation first.

Exercise bolsters immune function

The immune system, as one of the fascinating portions of our physiology, operates like all our systems, working optimally only when many factors are balanced.

Exercise bolsters immune function through its effects on inflammation, similarly to the other foundations. As we walk through the studies demonstrating protective effects against infection, besides being encouraged to get moving and leave our sedentary lifestyles, we will see it is almost always inflammation that plays the role of mediator between exercise and infection prevention.

Medical research has shown that the right amount of exercise decreases a variety of infection risks both in animal and human studies.

Lowder, for instance, showed that mice that had a pre-emptive exercise program fared better in terms of death rates when they contracted the influenza virus. Even back in 1993, Nieman demonstrated that elderly women who went through a 12- to 15-week exercise program experienced lower rates of upper respiratory tract infections.

But before you turn up the treadmill to full speed or sign up for that cycling class, take heed that even with exercise you can get too much of a good thing. Moreira examined the widely recognized phenomenon that excessively intense exertion, even in well-trained athletes, can temporarily increase susceptibility to viral infections. Apparently, we should aim for an optimal dose to strengthen our immune defenses. Common sense tells us that the optimal level varies for individuals based on their prior fitness level.

Our bodies need rest

After exercise or other exertion, our bodies need rest. The immune system, just like our brain, muscles, and other systems, needs some downtime, particularly sleep, to continue optimal function. This fact has been demonstrated by several studies. Patel evaluated over 56,000 middle-aged female nurses with similar health characteristics over two years to determine if self-reported sleep duration affected the risk of pneumonia occurrence. They found that those who reported less than five hours per night on average had higher rates of pneumonia if the person also reported that they felt they were getting too little sleep.

While many will continue to search for that magic supplement or pharmaceutical which, if taken religiously, will provide immune protection from viruses like COVID-19 or the common cold, foundations are critical.

Interestingly, in the study, prolonged sleepers (over nine hours per night) also demonstrated increased pneumonia risks.

Among others, studies by Cohen and Prather went beyond just observing subjects for a period of time after self-reports of sleep patterns.

Both studies actively gave adolescents in the study a nasal wash with actual rhinovirus, the primary cause of the common cold, and counted how many of them developed symptoms. Those with shorter sleep patterns demonstrated higher rates of common cold symptoms.

With a little internet searching, the list of studies linking adequate sleep with optimal immune health leaves little room to deny the importance of being wellrested for immune health in an age of COVID-19. Other studies showing that sleep helps to keep inflammation under control further drive home this point.

Gut health connection

While the connections between exercise and sleep with immune function may be more obvious, the connection with gut health is not quite as intuitive.

The first connection becomes obvious when one considers that proper nutrition for immune function requires feeding a nutritious diet to a healthy GI tract (Childs). The second connection between gut bacteria and inflammation requires a little more thought and research support.

Beyond simple nutrition, widespread research supports the need for balance in inflammation for immune optimization. Consider research by Santiago-Lopez which demonstrated that probiotics given to infants could reduce proinflammatory Th1 and Th17 cytokines such as IL-17 and IFN-γ while raising “production of inflammation resolving cytokine IL-10.”

This report is just the tip of the iceberg in research into ameliorating inflammation through dietary intervention into the GI function.

Besides the connection with inflammation, a growing amount of research has shed light on the importance of gut barrier function at the microscopic level. A study by McKeen describes how increased amounts of prebiotics, fiber, and other nutrients that enhance gut bacteria contribute to stronger gut wall barriers. These barriers are critical for immune function across the entire body.

Emotional levels

The final foundation for immune health is our emotional state, especially our level of stress. As early as the 1980s, pioneering research by psychologist Janice Kiecolt-Glaser, Ph.D., and immunologist Ronald Glaser, Ph.D., of The Ohio State University College of Medicine demonstrated that medical students were immune-suppressed during their three-day final exam period. They found lower levels of natural killer cells, lower levels of T cells, and very low levels of interferon-gamma, an immune system booster, meaning at least three important parts of the immune system were temporarily suppressed by the increased stress of final exams.

Our emotional stress response can modify how much cortisol is produced by our adrenal glands. Cortisol rises in response to physical or psychological stressors, and this higher cortisol can lower immune function while opening GI barriers to further inflammation. Spiritual health and a calm response to stress can prevent harmful effects.

While many will continue to search for that magic supplement or pharmaceutical which, if taken religiously, will provide immune protection from viruses like COVID-19 or the common cold, foundations are critical. The time and financial investment in a supplement are of little value until we balance our exercise, sleep, GI function, and emotional health. With these foundations, we as individuals and as a society can proceed into the new year aware and prepared for 2021 and beyond without undue fear.

In our next installment, we’ll move to what comes after foundations are laid.

Dr. Eric Potter, Internal Medicine and Pediatrics, founder of Sanctuary Functional Medicine DBA (), offers functional medicine care to patients and the public in his Franklin, Tennessee, office and online with


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