How Exercise and Nutrition Affect Our Immunological Health


It prevents virus reactivation, residual inflammation, cytokine storm, and other infection-related problems— including COVID-19.
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Exercise and Antiviral Defense

While exercise has not been shown to fend off coronaviruses, it reduces unnecessary chronic inflammation which frees up immunological resources to fight infections.

Exercise has long-lasting effects in lowering chronic low-grade inflammation in those healthy or with diseases like HIV, cancer, diabetes, obesity, etc., Professors Richard J. Simpson and Emmanuel Katsanis at the University of Arizona said in a paper published in Brain, Behavior, and Immunity titled, “The immunological case for staying active during the COVID-19 pandemic.”

Physically active people are also more resistant to respiratory illnesses. Exercise enhances the immune responses against all sorts of viruses, including influenza and common cold rhinovirus, the professors added. Mice engaged in physical exercise of moderate intensity, for instance, did not die from influenza-induced cytokine storm in the lungs compared to inactive mice.

Exercise further prevents the reactivation of latent viruses. This is encouraging given that coronaviruses are known to establish latency in the host, which scientists think might reactivate and cause neuropsychiatric symptoms decades later.

“Physically active individuals also exert better control over their latent viral infections, even during periods of isolation and confinement,” Professors Simpson and Katsanis said. A recent study conducted at their laboratory showed that physically fit astronauts are 40% less likely to reactivate their latent herpes virus during a space mission.

Even if the virus reactivates, more fit astronauts have fewer virus copies than the less fit ones, indicating a less severe and contagious infection. “Latent viral reactivation is a hallmark of compromised immunity, which, in this context, we deem to be due to the stressors associated with isolation and inactivity as a result of confinement on the International Space Station,” the professors remarked.
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Exercise and Immunological Health

Exercise improves immune response via a myriad of methods. Professors Simpson and Katsanis said that “a key mechanism is the frequent mobilization and redistribution of effector lymphocytes.” Lymphocytes are white blood cells such as natural killer cells, T-cells, and B-cells that fight pathogens.

Another bonus is that exercise releases catecholamines like adrenaline that fuel the “mobilization and redistribution” of lymphocytes. In a sense, exercise makes lymphocytes “look for a fight,” the professors said, boosting immune surveillance and patrolling in many organs and tissues.

Exercise has also been shown to improve immune responses to influenza and pneumococcal vaccinations in older people. “This could be important to help our seniors develop better immunity to an anticipated COVID-19 vaccine and minimize future complications should a second wave of the virus occur,” Professors Simpson and Katsanis wrote.
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Nutrition and Antiviral Defense

The Western diet — high in calories, refined sugars, and processed fats — drives chronic inflammation by hyper-activating innate immunity while suppressing adaptive T-cells and B-cells responses, said Michael J. Butler and Ruth M. Barrientos, professors at the Ohio State University, in a paper titled, “The impact of nutrition on COVID-19 susceptibility and long-term consequences,” in Brain, Behavior, and Immunity.

A lower adaptive T-cell and B-cell count — and increased innate neutrophil counts — were more evident in severe COVID-19 cases. Obese mice on a calorically rich diet are also more susceptible to severe influenza infection due to a delayed response from the compromised B-cells and T-cells.

Nutrition and Immunological Health

Feeding mice with a 60% fat diet increased the infiltration of macrophages (an innate immune cell) into the lungs and alveolar cells when exposed to a foreign antigen. “This is especially relevant to COVID-19 patients given the high rate of infection among lung alveolar epithelial cells and the involvement of lung tissue inflammation and alveolar damage in COVID-19 pathology,” Professors Butler and Barrientos emphasized.

For these reasons, the professors assert that healthy, whole foods should be made more accessible and convenient to the general population. “Studies show that consuming healthy foods has a rapid anti-inflammatory effect, even in the presence of obesity pathology,” Professors Butler and Barrientos said.

In a preprint titled, “Optimal Nutritional Status for a Well-Functioning
Immune System is an Important Factor to Protect Against Viral Infections,” Philip C. Calder, a professor of nutritional immunology at the University of Southampton, emphasized a similar issue.

“A wealth of mechanistic and clinical data show that vitamins…trace elements…and the omega-3 fatty acids [EPA and DHA] play important and complementary roles in supporting the immune system,” Professor Calder wrote. “Inadequate intake and status of these nutrients are widespread, leading to a decrease in resistance to infections.”
Optimal Nutritional Status for a Well-Functioning Immune System is an Important Factor to Protect Against Viral Infections.Calder et al. (2020)

The Case for Long-term Immunological Health

While many COVID-19 patients will recover, scientists and physicians are worried about the possible long-term repercussions on the lung or neurological health, Professors Butler and Barrientos said. Immune responses against viruses might persist long-term, especially in those whose immune system lacks anti-inflammatory or regulatory effects. An improper, residual immune response could then fuel the risk of other chronic diseases.

“The large number of people that will recover from COVID-19 may lead to a spike in chronic medical conditions that could be further exacerbated by unhealthy diets,” the professors wrote.

Maintaining immunological health is also important for those quarantined. In a recent paper published in Nature European Journal of Clinical Nutrition, Farah Naja and Rena Hamadeh, researchers at the American University of Beirut, raised the health issues associated with confinement.

It increases inactivity and sitting time, they said. “The low physical activity levels, even for short periods, could negatively affect physical and mental health.” Altered eating behaviors such as frequent snacking may also accompany confinement. This could lead to increased calorie intake which, combined with sedentary behaviors, promotes poor immune health, Naja and Hamadeh concluded.

In times like this, while social distancing and hand hygiene are mandatory to prevent infection, a well-regulated immune system is nevertheless important to eliminate pathogens and deal with post-infection repercussions, according to Professor Calder.

This article was originally published in Microbial Instincts with minor modifications.

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