Think of your immune system as your body’s protective shield: It’s a wildly intricate system of cells, tissues, and organs that work together to keep you safe from bacteria, viruses, and other potential bad guys that can make you sick. So it only makes sense that you’d want to do everything you can to keep it in good shape during the thick of cold and flu season—especially if you live with a chronic condition (say, an autoimmune disease or immunodeficiency disease) that affects your body’s ability to fight germs.1
You’ve probably heard of various immune system boosters and wondered whether taking a trendy supplement or drinking green smoothies will actually give you an illness-fighting edge. But when you consider how the immune system actually does its thing, the idea of giving it a boost doesn’t make a whole lot of sense, Alice Knoedler, MD, an asthma, allergy, and immunology specialist in St. Paul, tells SELF.
Simply put: “No, it’s not possible” to rapidly boost your immune system, Mark H. Kaplan, PhD, the chair of the department of microbiology and immunology at the Indiana University School of Medicine, tells SELF. But there are things you can do to support this crucial part of your health—and it’s all pretty basic stuff. Here’s what the experts say.
First, it’s important to have a general idea of how the immune system works.
Your body’s defenses fall within two categories: innate and adaptive. The first line of protection is the innate immune system, which is a series of barriers that prevent intruders from setting up shop in your body, Dr. Knoedler explains. This generally includes things like your skin and mucous membranes that act as a physical barrier, and cells and proteins that spring into action if germs happen to wiggle their way past these blockers.1,2
The adaptive immune system is more specific, Dr. Knoedler explains; it uses specialized defensive cells and antibodies to mount targeted attacks on invaders that the innate immune system couldn’t stop. It also develops “memory cells” that remember the substances it’s targeting so it can fight them off more quickly and effectively the next time it encounters them.2
A lot of how your immune system behaves today depends on what happened in your past. While the basics of your body’s functional defenses are universal, the strengths and vulnerabilities of any one individual’s immune system depend on factors that are out of your control, Nicolai Van Oers, PhD, a professor in the department of immunology at UT Southwestern Medical Center, tells SELF. Some of this comes down to genetics, Dr. Van Oers explains, while a lot of it is influenced by what kinds of viruses and bacteria you are exposed to during your life (naturally and via vaccination), and therefore, the memory cells that your adaptive system has created. That’s why some people are just better at fighting off certain kinds of infections than others.
The idea of boosting your immune system doesn’t make sense for lots of reasons.
Your immunity isn’t one single thing that you can pump up on demand—again, it’s a highly evolved and complicated system. “The immune system is amazing,” Dr. Knoedler says, and it really knows what it’s doing. “There are so many types of cells involved,” she explains. “That’s one of the things that is hard [to make sense of] with immune boosters. What is it specifically supposed to boost? It’s an entire system, it’s not one cell.”
The word boost also falsely implies that you might want to multiply the number of immune cells in your body, Dr. Knoedler says. “We don’t want more immune cells. We just want the ones we have to be able to function normally and carry out their primary roles,” she explains. And the idea of supercharging your immune response doesn’t make sense, given that overactive immune responses can cause excessive amounts of inflammation that make people feel terribly ill, Dr. Kaplan points out.3 “What you really want is a competent immune response,” he says.
Semantics aside, is there anything that’s proven to make your immune system more competent and better at its job? The truth is there is a serious lack of data behind most things that are touted as immune boosters. “A lot of these ads for supplements and superchargers and quick fixes…these things have never been tested in clinical trials,” Dr. Kaplan says. (Reminder: The US Food and Drug Administration does not evaluate or regulate supplements in the same way that it strictly oversees drug development and approval—meaning that these pills may not even contain what the label claims.)
“When we look at data on vitamins and herbal supplements and their impacts on viral infections as a whole, most of them have not been shown to [have an] impact,” Dr. Knoedler says. At best, “Sometimes something shows some very small benefit in one study, but it doesn’t in another [study].” (Vitamin D is one example.4) There’s also a lot of variation in the dosage, formulation, brand, and frequency that’s used in research. Plus, while the lengths of the studies vary, they’re most often carried out over weeks or months, Dr. Knoedler says—not exactly instant.
Certain supplements can absolutely help correct vitamin or mineral deficiencies caused by malnutrition, a health condition, or aging, Dr. Kaplan says. In that case, supplements can bring a person back to the baseline that their immune system needs to run smoothly. But for someone who gets plenty of essential nutrients regularly—which is easy enough to do by eating a varied diet, Dr. Van Oers notes—there’s no solid evidence for an extra boost. Generally speaking, “If you’re not deficient [in a nutrient], then adding more above the normal level doesn’t make your immune response any better,” Dr. Kaplan says. (Taking supplements also comes with health risks; many of them can cause potential side effects or interactions with various medications, per the National Institutes of Health. It’s a safer bet to get a doctor’s opinion before you pop a new pill.)
There are ways to support your immune system, though.
“Given that there are so many components and intricacies of the immune system, we just want to help it work as a whole like it’s supposed to,” Dr. Knoedler says. There are some basic habits that have been shown to support a well-functioning immune system over the long-term, she says. Here’s a breakdown:
While there aren’t any magic pills or single immune-boosting foods, eating a diverse diet that’s rich in plants is a great place to start. It’s not about pounding celery juice for a few days in a row: “Generally, these are long-term dietary changes,” Dr. Van Oers says. On a basic level, eating well is the best way to maintain a solid balance of vitamins and minerals in your body, which supports the functions of your immune cells and allows them to live up to their potential.5
Loading up on high-fiber fruits, vegetables, whole grains, and legumes also seems to support the growth and maintenance of beneficial microbes in your body, and more specifically, your gastrointestinal tract (which is pretty important, since up to 80% of your immune cells hang out in your gut).6
“Sleep is key for healthy immune function,” Aima Ahonkhai, MD, MPH, an assistant professor of medicine in the division of infectious disease at the Vanderbilt Institute for Global Health in Nashville, tells SELF. As you log your seven to nine hours each night, your body releases protective proteins called cytokines that help to regulate immune function, Dr. Ahonkhai explains. “This is actually why we sleep more when we are fighting an infection,” she says. “So without sufficient sleep, our immune function is weakened.” (Here are some tips on how to get better sleep if you struggle in that department.)
Regular exercise—generally defined as at least 150 minutes of moderate-intensity movement each week—also increases the release of cytokines (the same ones that roll out while you sleep) and circulation of immune cells called lymphocytes (white blood cells that help fight infection) throughout your body, which allows them to better identify and fight potential threats, Dr. Ahonkhai says.7 “Exercise also improves sleep and decreases stress, which feeds back to support the immune system,” Dr. Ahonkhai says.
You can overdo it, though. Research has found that repeated, strenuous exercise—think, daily marathon training—can actually suppress your immune function.7 (Learn more about how to strike an immune-supporting sweet spot with your workouts here.)
Yeah, being told to stop stressing is easier said than done. But if you can pull it off, it can make a difference in your well-being, John Sellick, DO, an infectious disease expert and professor of medicine at the University at Buffalo SUNY, tells SELF. “Think of it from the point of view of a generally healthy lifestyle,” he says. “If you’re working long hours, aren’t sleeping much, and are constantly stressed, you’re not looking at the things that you need to do to maintain your health.”
Short-lived stress can actually be protective, as it “produces an inflammatory response” in your body and increases the level of those all-important cytokines that help fight off infection or other threats, Dr. Ahonkhai says. But when the stress is chronic and all-consuming, that response can become harmful to your immune system over time, because it’s constantly activated.8 (If you feel tension in your shoulders right now, might we suggest these stress-relief activities and tips to reduce anxiety?)
Dr. Sellick says most adults should plan to get their annual flu shot (ideally before the end of October) and their updated COVID-19 vaccine (the timing will vary based on your last shot or infection). Some adults should also ask their doctor about the new RSV vaccine, the Centers for Disease Control and Prevention notes. These vaccines help prime your immune system so it will be ready to deal with these viruses if you encounter them, which ultimately lowers your risk of getting seriously ill, Dr. Sellick says.
If you have insurance or can swing the cost, seeing a primary care doctor on a yearly basis gives you a chance to talk about any physical or mental health issues you may be experiencing. It also allows your doctor to ask questions and perform basic exams to keep tabs on your well-being, Dr. Sellick says. “There are going to be specific things that need to be looked at: your heart rate, blood pressure, cholesterol levels,” he says. “This is always a good opportunity to go over things that maybe aren’t pressing but are still going on with your health.” During this check-up, your doctor can “also recognize early signs or symptoms of a weakened immune system,” and potentially intervene if legit concerns come up, Dr. Ahonkhai says. (You can search for a low-cost health center in your state here.)
All of these behaviors have a cumulative effect on your immune system (and health in general), so you should do your best to make them long-term, consistent habits, Dr. Van Oers says. As enticing as the idea of giving your immune system an instant glow-up might be, the truth is “there’s no overnight fix,” Dr. Van Oers says. Slow and steady wins the race!