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Take a quick skim of your social-media feed, and you’re sure to run into at least one post claiming to hold the secret supplement or trick to prevent or cure COVID-19.

We’re also bombarded with images and stories of severe cases involving cytokine storm and acute respiratory distress syndrome (ARDS), the potentially lethal hallmarks of end-stage infection. Amidst the daily headlines, widespread fear, and strong opinions, it’s no wonder many are scrambling to gain a sense of control and protection from this novel virus.

Is there anything we can do to protect ourselves? Can we reduce the risk of cytokine storm? What’s the relationship between nutrition and COVID-19? Is there a miracle pill? And, if we can, should we be boosting our immune systems?

A recently published review out of the University of Southhampton in the United Kingdom offers some insights, summarizing the relationship between nutrition, immunity, and COVID-19. This British Medical Journal (BMJ) review, together with other available data, provides context on what to consider before boosting the immune system.

Semantics Matter: Boosting vs. Balancing

Proponents of “boosting the immune system” mean well, but the verbiage here may not be entirely accurate. It’s important that the immune system is in balance.

This involves not only having the right barriers to protect us from infection in the first place (such as enough stomach acidity to kill pathogens), but also the ability to manage infection when it does occur. As such, we need the immune system to activate appropriately — at the right times, with the right intensity, and for the right duration.

On the other hand, an imbalanced immune system — either under- or overactive — can cause problems. For example, fighting off an infection successfully does require inflammation. However, too much inflammation and overactivity can damage healthy tissues. This is the case with autoimmune conditions, allergies, asthma, and — in more extreme circumstances — cytokine storm.

If the immune system is underactive, as is the case in certain genetic disorders, HIV infection, and chemotherapy treatment, for example, the initial inflammatory response to fight off the invader might be insufficient.

Hence, balance is key.

Immune Complexity

To go a bit deeper, our immune system can be thought of in two categories.

Our innate immunity is general and involves barriers such as mucous membranes and stomach acidity. It can recognize broad categories of invaders, such as bacteria, viruses, fungi, and parasites.

Our adaptive immunity is learned and involves responses to specific pathogens.

Generally, bacterial infections are outside of our cells. Our immune system works to engulf them, kill them, and present them to certain immune components called T-lymphocytes. From there, protective antibodies to that specific bacteria can be produced.

In the cases of viruses, our cells are actually invaded and hijacked. The entire cell is presented to the T-lymphocytes and then killed. Our “natural killer cells” also play a role in that they can identify when our cells are infected.

To attempt to give us future protection, immune memory to specific invaders can be built. This can last for months to decades, depending on the type of pathogen.

Nutrition and Balanced Immune Function

By now, you’re probably thinking that the immune system sounds a bit like a warzone — and that’s a fair comparison. It’s intelligent, complex, and ever-changing.

As a result, there’s no one thing to do or one thing to take to “fix” your immune system. Our nutrient status and levels of vitamins and minerals, however, play a significant role in how well our immune systems are functioning, including the following:

  • Vitamin A is required for a healthy digestive lining, which is one of our main exposures to the outside world. After all, we’re not eating and drinking in a sterile environment. Natural killer cells also need vitamin A.
  • B-vitamins are needed for various immune responses, including antiviral defenses. Folate and vitamin B6 support the spleen’s and thymus’ production of immune cells, while vitamin B12 is involved in the effort to engulf and destroy bacteria.
  • Vitamin C is needed for supporting the physical barrier to infections and antiviral activity of natural killer cells, as well as for engulfing bacteria. Some studies show it can help reduce the duration of a cold and, in those who are active, can reduce the number of colds. Other studies suggest it can play a role in the prevention and treatment of pneumonia. 
  • Vitamin E has a demonstrated role in antibody production and natural killer cell function in animal studies. In humans, it’s shown promise in supporting a better response to vaccination and a lower incidence of certain respiratory tract infections in the elderly, along with the effects on pneumonia risk in smokers. 
  • Selenium is needed to produce T-lymphocytes, B-lymphocytes, and antibodies. Some studies show that in those with low selenium, certain infections such as the flu can mutate, essentially allowing new and less understood versions of disease to develop. Research shows that 100 to 300 micrograms per day could be supportive of immunity.
  • Vitamin D receptors are found on immune cells, and certain cells can even make vitamin D, suggesting it has a crucial role. The role of vitamin D is complex, as it can upregulate certain parts of the immune system and downregulate others. Research shows a correlation between vitamin-D deficiency with respiratory tract infections, pneumonia, and less protection from the flu shot. There are a lot of health benefits of vitamin D — and avoiding deficiency with steady intake is important.
  • Iron is similar to vitamin D in that its role is complex. On one hand, certain infections and inflammatory pathways thrive with iron. On the other hand, iron is required for producing T-lymphocytes, increasing natural killer cell activity, and killing bacteria. Certain studies show better outcomes when iron supplementation is given concurrently with omega-3 fatty acids.
  • Zinc is a key stakeholder in the body’s adaptive immune response and is needed for the production of T-lymphocytes. With viruses that have similar properties to coronavirus, it’s been suggested that zinc can inhibit some functions required for the virus to replicate.
  • Omega-3 fatty acids could have a role in controlling inflammatory processes, which can spiral out of control in the late stages of infection, such as with ARDS. Some observational studies in patients with ARDS and lung injury have shown promise with omega-3s in combination with antioxidants.

This list is not exhaustive: Optimal immune function also requires other nutrients, such as copper and manganese. Our microbiome — the balance of bacteria in our digestive tract, skin, mouth, and genitals — might play a role in modulating our immune system as well.  

Nutrition and COVID-19

It’s important to note that there are no published nutrition studies related to COVID-19. However, that doesn’t render this information useless.

The literature shows that both aging and being underweight or overweight can negatively impact immune function and susceptibility to infection, as can underlying chronic health conditions. Advanced age and overweight/obesity, in particular, are associated with less than favorable changes in inflammatory markers.

Regardless, even if you’re normal weight and not of advanced age, your nutrition matters. The BMJ review authors concluded:

“It seems likely that individuals with suboptimal intakes of a range of essential nutrients are likely to show suboptimal immune responses; this probably contributes to the variation in immune outcomes that is seen in the general population.”

Next Steps

Achieving a healthy, balanced immune system demands consistent, balanced nutrition, regular exercise, and adequate sleep and stress management.

It’s important to master the basics first. Mega-dosing specific nutrients, herbs, or botanicals may be useless at best and harmful at worst. There are no miracle cures or preventions, and there’s no such thing as good immunity in a pill.

And there are no magical quick fixes to reverse the detriments of a nutrition approach filled with highly processed fat and refined grains that are common with frequent takeout orders, fast food, and refined snack foods. While stress might be higher and the amount of time spent at home might be more than you’re used to, resist the urge to turn to nutrient-devoid convenience foods as much as possible.

Amid current events, there’s never been a better time to prioritize your nutrition and fill in nutrient gaps. Start with high-quality proteins (such as fish, meat and poultry), ample amounts of colorful fruits and vegetables, some healthy fats (such as nuts, seeds, and olive oil), and nutrient-dense carbohydrate choices (such as lentils or sweet potato). Then, consider a reasonable, supportive, general supplement regimen.

Many of us are overfed from a caloric standpoint and undernourished from a nutrient standpoint. This has detriments for both immune function and our broader health status — yet it’s largely within our control, and that’s good news in the time of COVID-19.

Yes, we need to take reasonable measures to reduce our risk of exposure, such as handwashing regularly and good hygiene practices. But we also need to remember the importance of sleep and the value of fitness and nutrition on our immune function. 

The review authors poignantly shared this summary:

“In essence, good nutrition creates an environment in which the immune system is able to respond appropriately to challenge, irrespective of the nature of the challenge. Conversely, poor nutrition creates an environment in which the immune system cannot respond well.”

It’s unlikely that COVID-19 is the only widespread health challenge we’ll have to face as a society. There is still an anticipated flu season next year, and as the last few months have shown us, we never know what’s around the corner.

Still, it’s not a reason to live in constant panic. While there are no guarantees when it comes to health, there is power in risk management. We each are personally responsible for our nutrition and lifestyle choices and their effects on our health.

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Samantha McKinney, RD, CPT

Samantha McKinney has been a dietitian, trainer and coach for over 10 years. At first, her interests and experience were in a highly clinical setting in the medical field, which ended up laying a strong foundation for understanding metabolism as her true passion evolved: wellness and prevention. She hasn’t looked back since and has had the honor of supporting Life Time’s members and nutrition programs in various roles since 2011.

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