By Brian Wallace, Ph.D., FACSM and Heather M. Anders, RD, LD |
For most of us, these are unparalleled times – facing a life threatening pandemic with all of the associated lifestyle changes that entails including social distancing, wearing masks, sheltering in place, lockdowns and the associated mental, emotional and physical attrition. However, when it comes to fighting viruses there are many traditional lifestyle strategies that take on even more importance that help keep us healthy not the least of which are exercise and nutrition.
Over the last several decades, nutrition and exercise have emerged as quintessential strategies for building super health and functional fitness. Research clearly demonstrates that they can both, independently and synergistically, have a dramatic impact on not just our energy, health and fitness but also the development and progression of a wide range of chronic diseases and conditions including: obesity, cardiovascular disease, cancer, diabetes, GI disorders, liver and kidney diseases, Alzheimer’s, arthritis, and osteoporosis. We now know they also play a significant role in promoting a healthy immune function which, of course, helps protect us against the pathogens that can cause disease including viruses, bacteria and other micro-organisms.
Understanding the association between exercise, nutrition and the immune system has important implications not only for us individually but also for public health in general. While this relationship can be quite complex (given the multitude of interacting variables), the connection between exercise and immune function typically assumes a J-shaped curve when graphed relative to exercise intensity. On the one hand, when compared to being sedentary, moderate intensity and duration of exercise typically has a protective effect – strengthening immune function by enhancing the antipathogenic activity of a number of components of our immune system such as immunoglobulins, macrophages, neutrophils, NK cells, anti-inflammatory cytokines, and T cells. Moderate intensity exercise is associated with a reduced incidence of infection and helps maintain a robust immune system compared with a completely sedentary state.
In contrast, high intensity, long duration exercise and heavy training including competitive events and personal best attempts have been shown to result in a transient depression of WBC function (key players in immunocompetence) and can trigger post-exercise immunosuppression. These high intensity efforts create an open ‘window of vulnerability’ post-exercise of depressed immune function that can last up to 48 hours, depending on the intensity and duration of the exercise session during which viruses and bacteria can increase the risk of developing an infection. NK cell and neutrophil function, various measures of T- and B-cell function, salivary IgA output, and other biomarkers of immune function are altered and linked with immune dysfunction and so an elevated probability of disease. Post-exercise immune system dysfunction is magnified when the exercise is greater than 90 minutes, high intensity (>75% VO2max), and (particularly) when coupled with low energy (calorie) intake, high stress levels and poor sleep patterns. Moreover, intense training for more than several weeks (overreaching) often causes an extended ‘window of vulnerability’ and even greater susceptibility to pathogens and immune dysfunction.
Nutritional status. Working in synergy with our exercise training program is our nutritional status. Using a nutrient dense diet rich in immune-building nutrients and calorically dense enough to meet energy needs will help support immune function and sustain your health and fitness in these stressful times. Malnutrition, on the other hand, can diminish the benefits of moderate intensity exercise and exacerbate the adverse influence of high intensity exercise on immunocompetence. Dietary deficiencies of protein, specific micronutrients and caloric intake have long been associated with immune dysfunction. Exercising in a low calorie state, for example, elicits greater elevations in stress hormones and an imbalance of a number of immune function biomarkers. The most efficacious nutritional strategies include an appropriate blend of whole food (bioavailable) sources – macronutrients including high biological value protein, essential fatty acids and a high intake of phytonutrient/polyphenol rich fruits and vegetables (local, fresh and organic being best) with a range of benefits including anti-oxidant, anti-inflammatory and anti-viral. An adequate intake of iron, zinc and vitamins A, C, D, E, B6 and B12 are especially noteworthy for sustaining immune function and appear to decrease the magnitude of exercise-induced immunodepression.
For example, sufficient intake of vitamin C is thought to elevate WBC production; with anti-inflammatory effects, vitamin A can facilitate the antibodies response to pathogens; vitamin D and E are key micronutrients in helping regulate the body’s immune function; and vitamin B-6 is essential to the synthesis of RBC’s. Furthermore, probiotic foods (e.g., live cultures in yogurt) help to increase the beneficial bacteria/microbiome in the GI tract and to regulate immunity in the rest of the body by managing inflammation. The fiber in vegetables and fruit also help produce a healthy microbiome in the GI tract, which is where 70 percent of our immune system resides. Nuts, seeds, and fat from plant sources (such as avocado or olives) are rich in micronutrients such as zinc, copper, selenium, iron, and many other vitamins and antioxidants. Even garlic contains compounds that help the immune system by stimulating cells important in fighting disease such as virus-fighting T-cells and can reduce the amount of stress hormones thereby keeping your immune function at peak levels.
Ketogenics. Those with clinical issues such as diabetes, heart disease, high blood pressure, cancer, and a compromised immune system are at a three-fold greater risk for severe COVID-19 complications including death. Although there is no direct research regarding the effect of the ketogenics diet on the coronavirus per se, recent evidence strongly suggests this very low carb, high fat diet may promote a healthy immune system by reversing these conditions including diabetes, hypertension, hyperinsulinemia, preventing inflammation, elevating protective T cells, and enhancing GI health and microbiome. Intuitively, it makes sense that it would be beneficial either directly and/or indirectly to help fortify us against a virus. Of course, for all their benefits, exercise and nutrition are not a panacea but rather lifestyle choices to help us weather the inevitable storms of life that constantly besiege us such as the current pandemic. To be clear, the focus should be on managing the magnitude of both internal (e.g., psychological ‘stress’ responses) and external factors (e.g., training intensity, duration and volume), as well as lifestyle strategies (e.g., nutrition and sleep patterns) to maximize health, fitness and minimize disease risk and together make us more ‘fit to fight’ CV-19 and future pandemics.
Dr. Brian Wallace is the chair of sports exercise science at the United States Sports Academy.
Heather M. Anders is the Director of Food and Nutrition Services at Noland Health Services.