In these challenging times, if we only could get a medication that would boost our immune system and response to viruses, lower all stress associated with being in a pandemic, and treat most of the pre-existing health conditions that are associated with a higher risk of dying from COVID-19, we would all be lined up for it! Guess what? We already have something that does all these things already—and that is physical activity.
Let’s consider its impact on how well your immune system works. While physical activity can boost your immune function, here’s what else we know about the immune system and all the lifestyles factors we can manage:
Exercise: A single workout may temporarily suppress your immune system, but chronic training (assuming it is not excessive) boosts immunity to the common cold, other viruses, and a whole host of pathogens (1). Being regularly active generally makes you less likely to get sick.
Stress: Any type of stressor, be it physical or mental, can weaken your immune system, most commonly through increases in levels of the hormone cortisol and other factors (2). Exercise overtraining raises cortisol levels and can make you more likely to catch a cold or the flu.
Sleep: Lack of sleep—particularly deep REM sleep—and short sleep duration cause a rise in cortisol levels that can dampen immune function (3). Many people with type 2 diabetes and overweight/obesity also have sleep apnea that interferes with getting quality sleep, making them more susceptible to getting sick. Better management of all of these conditions helps.
Nutrition: Chronic malnutrition lowers the ability of the immune system to function optimally. Low levels of vitamin D (which acts as a prohormone) in the bloodstream has also been tied with lower immunity, and many people with diabetes and older adults have low vitamin D status. Getting adequate vitamins, minerals, and calories in your diet can boost your immunity.
Alcohol: While a moderate intake of alcohol may give you some health benefits, abuse of alcohol suppresses your immune system (4). “Moderate” is one drink per day for females, two for males—and there is no rollover from one day to the next if you miss one!
Smoking: Tobacco smoking increases inflammation and lowers immune function, and it may also lower your immune response to certain vaccines. Quitting smoking can help restore immune function.
We also need to discuss how our bodies react to vaccinations. All of us are facing possible vaccination for COVID-19 once a safe and effective vaccine is available. You may be, like I was previously, assuming that vaccines work the same for everyone. In reality, there is no guarantee of a universal and equally protective response, and a whole host of factors (inside your body and out) can impact how well a vaccine actually works for you (5). Not surprisingly, all of the lifestyle factors listed above can impact the strength of your immunity post-vaccination, and making improvements in any/all of them can help. But your age can also have a negative effect.
COVID-19 is unlikely to be the last threat to our collective health, so it is worth discussing why we are more vulnerable to threats to our immune system as we get older. For starters, older adults have a less robust immune response to everything, including strains of influenza, and they suffer from a more rapid waning of antibodies. Basically, our immune systems are getting less robust and effective as we age—and that potentially impacts our response to vaccines.
Generally, older adults have a lesser immunity to any virus that they have been vaccinated against, and that will likely include the current global coronavirus once a vaccine is available. However, engaging in regular aerobic training improved flu vaccine responses in a group of older adults who had been previously sedentary (6): participants who did a regular moderate-intensity physical activity like brisk walking were 30 to 100 percent more likely to have an antibody response sufficient to keep them from getting the flu. Although research on this topic remains limited, exercise is likely to help boost the immune systems in people who are currently sedentary and start being active.
Other confounding health issues may make immune responses weaker when you are exposed to a virus or vaccinated. For instance, many seniors with diabetes develop kidney disease requiring dialysis. In these individuals, many fail to have an adequate immune response when given a vaccine for hepatitis B; how well it works depends on their age, how long they have been on dialysis, their diet, and other factors (7). In children (and adults) with type 1 diabetes, certain vaccines have been shown to be less effective, particularly when they also have celiac disease and consume gluten (8).
So, what can you do? Fight back by adopting the healthiest lifestyle that you can—one that includes being regularly moderately active—and stay as healthy as you can for when the next virus comes along. Protect yourself with a daily dose of exercise!
References:
1) Cerqueira É, Marinho DA, Neiva HP, Lourenço O. Inflammatory Effects of High and Moderate Intensity Exercise-A Systematic Review. Front Physiol. 2020 Jan 9;10:1550. doi: 10.3389/fphys.2019.01550. PMID: 31992987.
2) McEwen BS. Central effects of stress hormones in health and disease: Understanding the protective and damaging effects of stress and stress mediators. Eur J Pharmacol. 2008 Apr 7;583(2-3):174-85. doi: 10.1016/j.ejphar.2007.11.071. PMID: 18282566.
3) Vgontzas AN, Zoumakis M, Bixler EO, et al. Impaired nighttime sleep in healthy old versus young adults is associated with elevated plasma interleukin-6 and cortisol levels: physiologic and therapeutic implications. J Clin Endocrinol Metab. 2003 May;88(5):2087-95. doi: 10.1210/jc.2002-021176. PMID: 12727959.
4) Rodríguez-Rabassa M, López P, Sánchez R, et al. Inflammatory Biomarkers, Microbiome, Depression, and Executive Dysfunction in Alcohol Users. Int J Environ Res Public Health. 2020 Jan 21;17(3):689. doi: 10.3390/ijerph17030689. PMID: 31973090.
5) Zimmermann P, Curtis N. Factors That Influence the Immune Response to Vaccination. Clin Microbiol Rev. 2019 Mar 13;32(2):e00084-18. doi: 10.1128/CMR.00084-18. PMID: 30867162.
6) Woods JA, Keylock KT, Lowder T, et al. Cardiovascular exercise training extends influenza vaccine seroprotection in sedentary older adults: the immune function intervention trial. J Am Geriatr Soc. 2009 Dec;57(12):2183-91. doi: 10.1111/j.1532-5415.2009.02563.x. PMID: 20121985.
7) Udomkarnjananun S, Takkavatakarn K, Praditpornsilpa K, et al. Hepatitis B virus vaccine immune response and mortality in dialysis patients: a meta-analysis. J Nephrol. 2020 Apr;33(2):343-354. doi: 10.1007/s40620-019-00668-1. Epub 2019 Nov 7. PMID: 31701375.
8) Opri R, Veneri D, Mengoli C, Zanoni G. Immune response to Hepatitis B vaccine in patients with celiac disease: A systematic review and meta-analysis. Hum Vaccin Immunother. 2015;11(12):2800-5. doi: 10.1080/21645515.2015.1069448. Epub 2015 Sep 17. PMID: 26378476.