Remember, a lifetime ago, when quarantine started? Did you dust off your apron and your pots and start making sourdough and home cooked meals? Did you also stock up on your favorite comfort foods and watch your month-long supply of snacks disappear by the end of the week? Quarantine has had a big impact on what we eat, and that matters because what we eat affects our immune system and overall health. Therefore, our diets are more important than ever in the fight against COVID-19, especially as the cold weather herds us all back indoors where physical distancing becomes harder. 

Poor diet (high in sugar, saturated fats and refined carbohydrates and low in vitamins, minerals, and healthy fats) is a risk factor for susceptibility to any illness. Our immune system has two major parts: the innate immune system that mounts an initial defense against an illness and the adaptive system that creates antibodies for long-term immunity. Both the innate and adaptive immune system are dependent on adequate nutrients such as vitamins A, C, D, E, B-6, folate, zinc, copper, selenium, iron, flavanols, fiber and omega-3 essential fatty acids. For example, zinc is used in the formation of cells in the innate immune system, and copper and zinc both help different types of white blood cells neutralize infectious agents. White blood cells fight infections by causing a local inflammatory response, which involves the release of signaling molecules called cytokines. However, it is possible for this inflammatory response to spiral out of control. A “cytokine storm” has been a hallmark of severe COVID-19 cases. Nutrients such as selenium, vitamin C and E and omega-3 fatty acids all play a role in reducing inflammation and oxidative stress. 

In addition, an unhealthy diet is a driver of many of the comorbidities associated with COVID-19. Individuals with underlying health conditions, such as obesity and type 2 diabetes, were 6 times as likely to be hospitalized and 12 times as likely to die from COVID-19 in the U.S. as of May 2020. Obesity impairs the immune system and may result in uncontrolled inflammation in response to COVID-19. Furthermore, obesity may make it harder for the adaptive immune system to respond to a virus, even after being vaccinated. A study at UNC found that vaccinated, obese adults were twice as likely to get the flu compared with vaccinated healthy-weight adults, ven though their immune systems mounted the same initial antibody response to the flue vaccine. 

So what to eat? Despite the cold weather and reduced availability of fresh produce, whole foods are more important than ever. Packaged foods are more likely to be moderately to highly processed foods, which, despite fortification, are associated with diets lower in Vitamins D and E, selenium, and zinc, among others. Highly-processed foods are independently associated with increased risk of cardiovascular disease and are high in sugar and saturated fat which contribute to pathology of obesity and type 2 diabetes. For a whole food diet, choose a colorful variety of fruits and vegetables for vitamins, minerals and fiber. Eggs are a wonderful source of B vitamins and are a complete protein. Sources of zinc include nuts, beans and lentils and omega-3’s can be found in fatty fish like salmon or your body can produce it (although in small quantities) from plants like flaxseed. 

Whether or not to take supplements depends on the nutrient and your diet. Vitamins B and C are safe because they are water soluble. That means your body will pee out whatever B and C vitamins it doesn’t use. Supplements are recommended for vitamin D, since most Americans are deficient in this vitamin, exposure to sunlight is going to go down in the winter, and it plays a crucial role in immune function. For omega-3’s, you’re better off eating fish than supplementing because there are lots of other beneficial, anti-inflammatory nutrients in fish. However, if you’re vegetarian, you should invest in a quality omega-3 supplement.

To reduce trips to the grocery store, you can stock up on frozen fruits and vegetables, which retain their nutrients. You can also buy fresh fruits and vegetables, make batches of curry or soup with lentils and beans, and freeze it for it later. Finally, remember that physical distancing does not mean social distancing; find a recipe and make it over zoom with a friend. Share in the comments below – what are your favorite fall and winter recipes?

I’m all about podcasts, here are a few of my favorites on the immune system and/or COVID-19:

The Model Health Show: 10 Ways to Fortify your Immune System

The Doctor’s Farmacy: Creating a Healthy Immune System

And special shoutout to a very nerdy and incredibly insightful biochem podcast, The Drive, which has an excellent episode on the immune system and COVID and another on the science behind a vaccine, along with a lot of other gems, go check it out.

Peer edited by Rachel Cherney

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