Vitamins To Boost Your Immune System? Not So Fast

It was only a matter of time for the snake oil peddlers of the wellness industry to take advantage of this pandemic. As early as February, televangelist Jim Bakker was holding up bottles of “Silver Solution” claiming its proven ability to destroy the coronavirus (the state of Missouri sued and he stopped). By March, web ads and socials posts swarmed the internet offering “immune-boosting” supplements, “antiviral” silver lozenges and essential oils to help ward off the virus. Industry forecasters project a 25 percent increase in sales of immunity supplements in 2020. If only this was the right medicine.

One problem? None of these products are proved to reduce your chances of getting COVID-19. The other? You can’t boost your immune system. Or, more to the point, with a respiratory disease whose deadly response is in fact due to the strong immune response itself, you wouldn’t want to. That’s right: “Immune boosting” is a big fat lie.

“Having done this for 25 years, I have never seen a food or nutrient that I would describe as ‘immune boosting.’ That phrase has no scientific meaning,” says Elizabeth Jacobs, Ph.D., a professor of epidemiology and biostatistics at the University of Arizona who is studying COVID-19.

The fault in that reasoning, say experts in immunology and virology, is that immunity just doesn’t work that way. Specialized groups of cells in the body work as a series of checks and balances designed to recognize and fight off any type of foreign invader — called antigens. These could be bacteria, parasites, fungi, or a virus. When those without medical degrees talk about “immune boosting,” they’re referring to the adaptive response of the immune system. When the body comes into contact with any types of germs, it usually stores information about them and how to fight it. Then, if it comes into contact with the germ again, it fights. Have a runny nose? This is not the virus itself, but an immune response. Constantly have a runny nose? That’s an overactive immune response.

As working immune systems do with all illnesses, they unleash white blood cells to fight off COVID-19. In some people, the virus causes an overreaction of the immune system called a “cytokine storm.” Researchers are still studying cytokines, small proteins released by white blood cells, but they appear to damage lung tissues and blood vessel linings, filling the lungs with fluid. This immune system overreaction is common among hospitalized COVID patients — with 75 percent showing signs of pneumonia in both lungs according to a study published in January.

In other words, immune systems are complex, “which is why it’s a gross oversimplification to simply state you can boost the immune system by doing x, y, or z,” says David Stukus, MD, an immunologist and assistant professor of pediatrics at The Ohio State University College of Medicine. “In general, people shouldn’t worry about their immune systems unless they have shown a pattern of getting sick or getting infections frequently,” Stukus says. “That’s the best indication that your immune system is compromised: that you’re getting sick more than a person normally would.”

Why We Fall for Promises of Boosted Immunity

Despite the fact that most people don’t need them, vitamin C supplements are extremely popular. The average American gets enough of it from food, Jacobs says, and if your body already has enough of a nutrient, it simply expels what it doesn’t need.

“I tell my students that if you keep buying Emergen-C, you’re just peeing your money out,” she says. “Eventually you hit saturation. With calcium, for example, the more you consume the less you absorb, because at a certain point the body is like, ‘I have enough, thank you.’”

Even if boosting immunity were actually possible, doing so wouldn’t be good for you.

“The interesting thing about these types of products is that boosting the immune system would actually be a bad thing,” Stukus says. That’s because the symptoms that come along with a virus, such as a runny nose and cough, are the immune system fighting it off. So if you “boost” an immune system already in balance, you’re causing an overreaction.

“While it might sound great, in reality, boosting an immune system that already functions well might actually disturb the balance between reactivity and tolerance,” says Dimitar Marinov, MD, Ph.D., an assistant professor of hygiene and epidemiology at the Medical University of Varna in Bulgaria.

In other words, part of the immune system’s job is to know when to turn off an immune response, too. An overactive immune system can lead to autoimmune diseases such as lupus, arthritis, and diabetes, says Michael Teng, Ph.D., a virologist and professor of internal medicine at the University of South Florida in Tampa.

You won’t develop lupus from too many vitamins, but too much of some vitamins and minerals can be toxic and cause other health problems. Excessive zinc supplementation, for example, can actually suppress immunity by interfering with copper absorption and causing a deficiency. Despite the risk that supplementation could cause health problems, or at least be a waste of money, Teng isn’t surprised that people are loading up on immunity-related supplements amid the pandemic.

“People are worried right now,” Teng says. “Everybody wants to have something they can take to protect themselves. But most of these supplement products are not drugs so they’re not regulated by the FDA. So they can make claims that aren’t necessarily supported.”

COVID Complications

We hear and read all the time that chronic inflammation is linked to an increasing number of diseases such as heart disease, diabetes, arthritis, and cancer. And antioxidants, such as vitamin C and zinc, are said to help reduce inflammation in the body, which has been linked to more severe COVID-19 infection and higher mortality rates. Many people put one and one together and conclude that vitamin C and zinc supplements might be good for disease prevention. These people, by and large, are not medical professionals.

It’s just not that simple.

The antioxidants theory circles the idea that when there’s inflammation inside the body, an oxidative process that causes damage is taking place, Stukus says, and antioxidants can reduce that. But not all inflammation, which is a generic term, is caused by this oxidative process. And importantly, it would be a mistake to make a leap from antioxidant research showing a decrease in inflammation to anything having to do with COVID-19. The inflammation that comes along with COVID-19 might not even involve the pathway an antioxidant supplement might target, Stukus notes.

“Frankly, to extrapolate from previous studies and say anything about what antioxidants can do to this brand-new virus is premature at best and harmful at worst,” he says. “This is just a massive opportunity for snake oil salesmen to double down on everything they’ve done for years.”

That there is some science behind some of these claims makes it more difficult for consumers to get a realistic picture of what supplements and herbal remedies do. You can search PubMed and find studies, for example, concluding that garlic has antimicrobial properties, that vitamin C seems to help prevent colds, and that licorice has antiviral properties. But ignoring relevant details about those studies — which supplement companies and customers often do — is called cherry-picking the data, Stukus says.

For example, garlic may have antimicrobial properties when applied topically, but this doesn’t have any bearing on whether a garlic pill can prevent colds (let alone COVID-19). One recent article describing immune boosters, for another example, recommends mushroom supplements and cites a published study to back up the claim. But the study was of women with cancer whose immune systems had been dampened by chemotherapy treatments, so it’s not really relevant for readers with normally functioning immune systems.

Supplement companies also have latched onto promising research of the human microbiome to sell probiotics. But much more research on how gut bacteria reflects and affects our health is needed before we can say that a probiotic might have any protective effect against coronavirus, Teng says.

“Probiotics do seem to have an effect on stimulating immune responses, but we’re not quite there yet in understanding how this works,” he says. “Having some benefit in general doesn’t determine whether creating the right kind of bacteria in the gut might have any disease-resisting benefit.”

There’s also a sliver of research supporting the benefits of colloidal silver, a favorite among anti-vaxxers, Jacobs says.

“Silver and other metals were shown a while ago to have some interesting antibiotic properties, where it’s almost a mechanical breakup of pathogens’ ability to affect the body,” she says.

“But when we read in a study that copper can kill germs out in the open, that does not equate to what happens when you eat copper,” she continues. “So I’d say we need to be really careful not to conflate what is observed in one of these metals and that consuming them is going to have a similar effect.”

Vitamin D has been part of the COVID conversation as well, with a recent study concluding that a severe deficiency in the vitamin might be linked to higher death rates from the virus. Although most people don’t quite get enough vitamin D and could benefit from supplementing, don’t assume more is better, Teng says.

“People with a D deficiency do seem to have trouble with their immune system but there’s no evidence that adding vitamin D on top of normal levels will help a healthy person,” he says.

What a Healthy Immune System Actually Looks Like

Even before COVID-19 started spreading in the U.S., 77 percent of Americans said they took daily supplements, according to a 2019 survey by the Council for Responsible Nutrition. The average American’s low risk for most nutrient deficiencies is unlikely to put a dent in sales.

Although many supplements are unlikely to hurt you, Stukus says he’s concerned that vitamin supplements might give people a false sense of security that could make them less likely to do things that do lessen the chances of getting the virus, such as washing their hands thoroughly or being diligent about social distancing.

A varied diet has a much bigger impact on the immune system and overall health, Stukus says. As does the “boring and unsexy” advice to get good sleep, exercise, and reduce stress, Jacobs adds. In fact, she says, it might be helpful to think of the pandemic as an opportunity to think about how to really make healthy changes to protect against diseases in the long term.

“One of the things we know makes us susceptible to disease is being stressed out, in addition to not eating properly and not getting exercise,” Teng says. “All these things are harder to do for a lot of us; it’s easier to take a pill and not worry about getting eight hours of sleep a night. But like losing weight, there’s no quick fix. You have to do the hard things.”