Over a year into the pandemic, vaccines are rolling out and it feels as if there’s finally a light at the end of the tunnel. For many Americans, however, there is still a bit of a wait before they can receive their shot, depending on the state they live in. As we strive to stay healthy while the country works toward building herd immunity, it’s natural to continue to look for ways to bolster your immune system. You may have heard claims that vitamin D could help combat COVID-19 (the jury is still out on that one), or maybe you’ve stayed up late Googling the benefits of probiotics. But is it really possible to truly boost your immune system? And if so, how? To start with, it helps to understand the basics of how the immune system works.

Okay, so how does the immune system operate?

“The immune system is complex, distributed throughout the body, and highly active,” explains David C. Nieman, a professor of biology at Appalachian State University, and director of their Human Performance Lab in Kannapolis, North Carolina, who specializes in research on nutrition immunology. “Good nutrition is needed to support the immune system’s varied functions, but this is achieved over time by high-quality dietary patterns.”

In other words, there’s really no such thing as a quick fix when it comes to your immune system. The experts agree that there’s a reason why it can be difficult to find studies proving that supposed immune boosters such as the ones listed above are effective. According to Nicolai van Oers, a professor of immunology, microbiology, and pediatrics at UT Southwestern Medical Center in Dallas, each individual is different in terms of what their immune system needs. “Many of the benefits suggested are documented in test-tube experiments and simply cannot be achieved in vivo because one can never take up the levels that are needed,” he adds.

Willow Jarosh, a registered dietician nutritionist based in New York City, echoes this sentiment. “In some cases, the immune boost you might see reported from a study is seen in people who were deficient to begin with,” she says. “So taking that nutrient may not have any benefit to someone who isn’t deficient.”

With that in mind, let’s take a look at some oft-touted immune boosters and what the experts have to say about their efficacy. And, as always, consult your doctor before deciding to take any supplements.

Which immune boosters actually work?

Acupuncture

Van Oers says that acupuncture may be able to reduce inflammation — with a caveat: “This is… very individual-specific and may not work in many people.”

And it seems to be the consensus among experts. “If acupuncture helps to reduce your anxiety levels, helps you sleep, etc., then there is a likely immune benefit,” says Jarosh. “It’s more about addressing something that may have been preventing the immune system from fully functioning as opposed to boosting the immune system beyond what it would otherwise be capable of.”

Niket Sonpal, an internist and gastroenterologist based in New York City agrees that acupuncture can be beneficial for stress reduction, explaining that “small studies have suggested it can be helpful in alleviating stress and anxiety which can have a positive effect on the immune system.”

Elderberry

“Elderberry is [a] supplement I get asked about quite often,” Jarosh says. “There is some research indicating that elderberry might help shorten [the] duration of influenza and sinusitis. But again, nothing conclusive.”

Sonpal says that any potential benefit from elderberries is all about the antioxidants. “Elderberries are packed with antioxidants and vitamins that directly boost the immune system,” he explains. “Epidemiological research has found links between antioxidant-rich diets and a reduced incidence of cancer.”

If you do choose to incorporate elderberry into your diet, talk to your doctor first, proceed with caution, and look closely at the supplement. And avoid uncooked elderberry, as it can cause stomach upset.

Garlic

Sonpal says that garlic could be another option to add to your diet, particularly aged garlic extract, which some studies have found contains heightened antioxidant properties. “Research is more clear in terms of garlic’s boosting of the immune system,” he says. “Scientists have also found compounds within garlic that increase the immune response in white cells, which helps them combat viruses and symptoms of sickness.”

According to Jarosh, “there are some studies that indicate garlic may be able to stimulate or support aspects of our immune system.” So feel free to use that as justification for adding twice as many cloves in your favorite recipes.

Probiotics

According to Sonpal, probiotics are live bacteria that help diversify our gut microbiome and help the immune system regulate inflammation. “The more diverse our bacteria colonies are in our gut, the better we tend to feel,” he says.

There is a catch, of course. “Without question, the bacterial species that live in the stomach and intestines can definitely influence the immune system’s behavior. However, simply adding probiotics does not change the normal populations of these bacteria,” explains van Oers.

“What is the appropriate diversity needed for this is not known and may differ from one person to another,” he continues. “A probiotic mixture is just that, a mixture, and is likely to be completely ineffective for most individuals.”

Turmeric

“Research has found that [turmeric] may help downregulate some inflammatory responses and help regulate immune responses in other cases,” Jarosh says. She stresses that researchers are still trying to figure out exactly how it does these things, which is an essential step when it comes to figuring out who can benefit from it.

Sonpal points to a few possible ways turmeric could help your body regulate the immune system. “The curcumin in turmeric serves as a prebiotic that helps feed the bacteria in your gut,” he explains. “It battles inflammation and cell damage as it has plenty of antioxidant content.”

He adds that it can also help boost your immune system by lowering stress: “Turmeric can also help lower cortisol levels, which are the hormones that trigger our fight-or-flight response when we are stressed.”

Vitamin C

Vitamin C gets a thumbs-up from van Oers, although he says it depends on where your body gets the vitamin. “[The] best source is from citrus fruits,” he says… Simply increasing vitamin C in the form of [taking a] vitamin results in most of the vitamin C not being absorbed through the stomach.”

Sonpal agrees that vitamin C plays an important role in your immune system because it “helps stimulate the production of lymphocytes, which are white blood cells that help protect the body against infection, [and it] allows white blood cells to function better and protects them from damage.”

“When people have pneumonia their vitamin C levels typically decline,” Sonpal adds. Studies such as this one have shown that vitamin C supplements may help with recovery time.

Vitamin D

There has been increased public interest in vitamin D ever since some research noted its possible connection to the immune system’s response to COVID-19.

“The role that vitamin D plays in keeping the immune system healthy is very complex because the immune system has to be perfectly balanced,” explains Sonpal. “Low levels of vitamin D have also been associated with frequent infections. In 2009, a National Institute of Health-funded study found low vitamin D levels associated with frequent colds and influenza.”

However, there’s a good chance that you don’t need vitamin D supplements. “Vitamin D can also boost the immune system,” says van Oers, citing its ability to help weaken infections such as influenza. “But this is generally when people do not get enough vitamin D from sunlight. And for most Americans, enough sunlight exposure occurs, even in winter.”

Zinc

The experts agree that zinc can be beneficial, but only if you need it, which is why it’s always best to speak to your doctor before starting any supplements. “Zinc can definitely improve immune functions, but this is generally in the elderly when the normal absorption of zinc has diminished,” says van Oers.

“With both zinc and vitamin D, the benefits are seen more in people who were deficient,” Jarosh concurs.

What can you actually do to boost your immune system?

All four experts emphasize the importance of a balanced diet. Nieman suggests not worrying about any one superfood or herb. Instead, increase your intake of fruits and vegetables that are rich in antioxidants and flavonoids.

Jarosh also advises eating a variety of nutrient-rich foods and warns against overdoing it with alcohol consumption as well as fad diets and cleanses. She points out that managing stress is an important part of immune system upkeep. “This can certainly include stress around dieting, especially with headlines focusing on people’s weight during the pandemic.” You may also find it helpful to cut back on consuming media that triggers stress or unhealthy habits for you.

Exercise is another vital piece of the puzzle. “Recommended amounts of moderate-intensity physical activity typically range between 150 to 300 minutes per week and are consistent with enhanced immunosurveillance and lowered risk for respiratory illness,” explains Nieman.

If more vigorous forms of exercise are beyond your reach for whatever reason, van Oers says that walking, yoga, and even meditation and breathing exercises can be beneficial as well. The most important thing is consistency. As Jarosh puts it, “Find a way to move regularly that you enjoy, or at least don’t hate.” Dancing around your living room to your favorite music definitely counts.

Other simple but essential habits for a healthy immune system include sleep (van Oers recommends getting seven to eight hours every night), staying hydrated, and washing your hands regularly and properly. And if you do take any vitamins or supplements, Jarosh advises that you see your doctor and “have basic blood work done to identify any places where you may be deficient and then supplement accordingly.”

Finally, if you can get the COVID-19 vaccine, van Oers recommends doing so. “Vaccinations are very important,” he explains. “For example, measles can wipe out 50 to 70 percent of the immune system’s memory for unvaccinated children if they become infected. COVID-19 can also wipe out components of the immune system, which increases a risk for other infections.