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If you check the news or scroll through social media right now, there’s a good chance you’ll see something about products, foods and drinks that boost immunity. One article says to try elderberry syrup, another suggests boiling garlic and others recommend loading up on vitamin C. There’s nothing wrong with adding an herb to your morning smoothie, and vitamin-rich fruits and vegetables have unequivocal health benefits. It’s also natural to seek out ways to protect yourself from getting sick during a global pandemic. But don’t let promises of immune-boosting cure-alls give you a false sense of invincibility — or make you waste money.
“You cannot boost immunity by just taking one or two things,” says Dr. Sean Leng, a professor of medicine, molecular microbiology and immunology at Johns Hopkins Medicine. “These things probably don’t hurt, but they’re not going to ‘boost’ your immune function overnight. The immune system is a very complicated system, as all systems in the body are.”
The immune system has two parts: the innate immune system and the adaptive immune system. The innate immune system includes our skin and the linings of our lungs and gut, all of which create physical barriers to keep pathogens (anything that causes disease) from entering the body. It also includes cells called macrophages and neutrophils that recognize pathogens and produce other molecules to attack the invader. “This isn’t pathogen-specific,” Leng explains. “You could have bacteria, the influenza virus or COVID-19 enter the body, and these cells will attack all of those.”
On the other hand, the adaptive immune system consists of T and B cells, which fight off specific pathogens, the collective term for viruses, bacteria, fungi and other types of microorganisms that can cause disease. It’s “adaptive” because these cells only evolve once you’ve encountered and recovered from a pathogen. “If you have a virus, after the infection clears, your body develops specific T and B cells against that particular pathogen so that it will be able to respond in a much stronger fashion the next time it encounters the virus,” Leng says. “The B cells produce antibodies to go out and neutralize the virus, and the T cells are cellular immunity. Those kill the other cells that are infected by the virus so the virus will not survive” in your body.
Although genetics influence our immune response, our individual life experiences and environments also play a big role. “Our immune system is constantly shaped by what we are exposed to,” says Dr. Dawn Bowdish, Canada Research Chair of aging and immunity at McMaster University. If we have been exposed to certain pathogens in our environment, then we’re more likely to develop specific immunities to them. In the case of COVID-19, humans had never been exposed to the virus before this outbreak, so no one had built immunity to it. That’s one reason it’s become such a widespread pandemic.
Lifestyle factors such as smoking, being inactive, eating an unhealthy diet and excessive drinking can also compromise the overall immune system. And “as we age, immune function declines,” Leng says, which may partly explain why older adults seem more susceptible to becoming severely ill from COVID-19.
All of these variables cause each of us to have different responses to different viruses. Some people can be exposed to the coronavirus and not be infected; some people will be infected but have no symptoms; some will develop symptoms but be able to manage them at home, and some will become very sick and need to be hospitalized.
In some cases, serious cases of COVID-19 are actually caused by the immune system overreacting. “A strong inflammation response fights infections, but in COVID-19, part of what is killing people is a strong immune response,” Bowdish says. At the onset, COVID-19 attacks the lungs, where it replicates and travels deep into the lungs. The immune system responds by releasing pro-inflammatory cytokines and other cells. But in some people, this reaction goes too far, setting off what’s called a cytokine storm. “The immune system is out of control,” Leng says.
The resulting inflammation damages the air sacs, which leak liquid in the lungs. “Water in the lungs happens very deep with this virus,” Bowdish explains. “That’s why so many need ventilator support. It’s just like drowning. Your lungs can’t get oxygen, and the heart compensates by beating harder and harder and harder and faster.” This acute respiratory distress syndrome can lead to death.
An overactive immune system can also lead to autoimmune disorders like lupus and rheumatoid arthritis as well as asthma. So if “boosting” the immune system means increasing the response, that’s not necessarily a good thing. Additionally, “the immune system does so much; some features that might be good for one thing might be bad for another,” Bowdish says. “I don’t know what ‘boosting’ would mean.”
However, there are proven ways to support a healthy immune system. “We need a good immune response against pathogens so that when a virus comes to attack us, it will kill the virus,” Leng says. “But when people talk about one food or a quick fix, that will not help, because the immune system needs to be maintained and fostered for longer periods of time. It builds up over the years.”
The first thing both Bowdish and Leng recommend is regular physical activity. A sedentary lifestyle is associated with impaired immune response. One reason may be that sitting appears to increase markers of inflammation. “Exercise is nature’s anti-inflammatory,” Bowdish says. “Moving and exercise can help support the health of multiple organs so the body can invest less energy in repairing those organs and more energy doing what it needs to do.”
A healthy diet also helps. Research links diets that are high in sugar and saturated and trans fats, and low in fiber and antioxidants, with immune dysfunction as well as changes in the gut microbiome, which affects our immune system. “A diet high in fiber, fruit, vegetables and good fats, and low in bad fats and sugars supports a healthy gut that’s not too leaky and a well-functioning immune system,” Bowdish says. The Mediterranean diet in particular may improve innate immune function, according to some studies.
And you can’t overlook good sleep, avoiding or quitting smoking, managing any chronic conditions, and maintaining a strong social network and good mental health, Leng adds. “The immune system isn’t alone in our body. It’s impacted by hormones and by the nervous system,” he explains. “One theory is that if we maintain our psychological well-being, it helps to create a good environment for the immune system.”
While you can forget about any magic supplement or other quick fix to “boost” your immunity, don’t forget about about the known ways to protect yourself against the coronavirus: Social distancing is critical, so stay home as much as possible, and when you do venture outside to exercise or visit the grocery store, stay at least six feet away from other people. COVID-19 can live for up to 24 hours on cardboard and up to three days on plastic and stainless steel, so wash your hands regularly. Lastly, if you do start to exhibit symptoms, call your doctor. Only go to the hospital if you have severe symptoms, Leng says. Globally, we may still be working on our immune response, but individually, there’s still plenty that’s within your control.