How To Boost Your Immune System

Ensuring that your immune system is ready to mount a strong defense can help keep you from getting sick during cold and flu season—or anytime, really.

"The best strategy at this point is two-fold: both prevention of infection and strengthening the immune system," Valerie LeComte, DO, an emergency medicine specialist in Southern Colorado, told Health.

With that in mind, Health reached out to healthcare providers to find the top immune-boosting habits they recommend. Some of those habits can help block the initial infection. And others fire up your system, so you can get better quickly if you come down with something. 

All in all, here are simple and easy habits to incorporate into your day-to-day routine to keep your immune system strong.

Eat Foods Rich in Antioxidants

"While no food or supplement can 'cure' or even 100% prevent you from catching a virus like [SARS-CoV-2] or the flu, some foods have been shown to help bolster immunity," Cynthia Sass, RDN, a registered dietitian nutritionist and Health's contributing nutrition editor, told us. 

Research has found that the following foods have some immune-boosting effects:

• Citrus fruits
• Red bell peppers
• Almonds
• Sunflower seeds
• Walnuts
• Beans
• Garlic

Focus on dark green, red, and yellow veggies and fruits to help fortify your system with phytochemicals, Lisa Ballehr, DO, a functional medicine practitioner based in Mesa, Ariz., told Health. Some evidence suggests that phytochemicals act like antioxidants, helping fight viruses. Aim for nine to 10 servings a day, said Dr. Ballehr.

Eat Anti-Inflammatory Foods

To boost your immunity, stock up on foods that have anti-inflammatory effects on the body. 

Many foods have both antioxidant and anti-inflammatory properties. A good place to look for anti-inflammatory properties is foods high in omega-3 fatty acids, such as oily fish like salmon, mackerel, tuna, and sardines. Research has found that foods with omega-3 fatty acids are known to help hinder processes in the body that promote inflammation.

Other anti-inflammatory food options include:

• Olive oil
• Legumes and nuts
• Unrefined cereals
• Fruits
  

Consume Probiotics

The bacteria in your gut may affect your body's ability to fend off infections. So, eating foods that contain "good" bacteria, organisms that are beneficial for gut health, Timothy Mainardi, MD, an allergist and immunologist based in New York, told Health.

Fermented foods and beverages—think kombucha and kimchi—are chock-full of "good" bacteria, also known as probiotics. You could also consider a probiotic supplement.

However, research has found that some probiotic foods and supplements may be unsafe for people with weakened immune systems—including those with chronic health conditions or undergoing chemotherapy. If you have concerns, check with a healthcare provider before taking probiotics.

Get Enough Zinc

The body needs zinc to support the immune system, said Dr. LeComte.

"There are multiple studies that show people with low zinc are more susceptible to infection," added Dr. LeComte. Additionally, zinc helps with wound healing.

The recommended amount of zinc is 13 milligrams for adult men and 9.2 milligrams for adult women daily. Typically, you can get enough zinc from foods like:

• Oysters
• Beef
• Cereals and oats fortified with zinc
• Lentils
• Peanuts
• Greek yogurt

Still, it may help to consider taking a zinc supplement after talking to a healthcare provider, suggested Dr. LeComte. A healthcare provider may test your blood to see if you aren't getting enough zinc from your diet.

Stay Hydrated

Hydration is key to a healthy body and immune system. Water serves several essential functions in the body, including:

• Acting as a vital nutrient of life
• Regulating your internal body temperature
• Metabolizing and transporting nutrients in the bloodstream
• Flushing out waste
• Acting as a shock absorber for the brain and spinal cord
• In pregnant people, acting as a shock absorber for the fetus
• Forming saliva
• Lubricating your joints

It's also important to drink plenty of fluids when you're ill. Water replenishes the fluid you're losing through your lungs every time you cough and from losses due to sweating.

Limit Alcohol Intake

Moderate alcohol consumption doesn't appear to positively affect your immune system. And some evidence suggests that binge drinking, or more than four drinks in two hours for women and five for men, impairs immunity.

"Alcohol temporarily increases the number of white blood cells, which are the infection fighters, in your bloodstream," explained Dr. LeComte. "But as your liver is clearing the alcohol from your system, your white blood cell numbers fall below normal for at least five hours. And while there does not seem to be any good data measuring white blood cell levels for smaller amounts of alcohol, it is assumed that even one or two drinks can blunt your immune system response."

As for heavy drinking, a study published in 2015 in Alcohol Research: Current Reviews found a link between alcohol use disorder and a possible susceptibility to pneumonia. So, if you're working hard to stay healthy, it's best to avoid or limit alcohol.

Work up a Sweat Regularly

One study published in 2019 in the Journal of Sports and Health Science described the following benefits of moderate to vigorous exercise:

• Powers your immune response
• Lowers your risk of illness
• Reduces inflammation

"Exercising regularly and eating healthy are the most significant factors for your immune system," noted Dr. Mainardi. 

In contrast, research has found that people with sedentary lifestyles are more likely to get colds or other infectious illnesses.

The Centers for Disease Control and Prevention (CDC) recommends 150 minutes of moderate-intensity aerobic activity weekly. Or, if you prefer vigorous exercise, the CDC recommends 75 minutes at that intensity.

A 15- to 20-minute at-home workout, jump rope or jog-in-place session, or a brisk walk around the neighborhood several times a week are good ways to work some sweat into your schedule.

Score Consistent Sleep

"There's an association with lack of sleep and getting sick," said Dr. Mainardi.

For example, in one study published in 2017 in Nature and Science of Sleep, researchers found disrupted sleep caused serious health ramifications, including:

• Stress
• Pain
• Decreased quality of life
• Adverse mental health outcomes
• Memory problems

Also, don't assume you can just catch up on sleep after a night or two of staying up late or tossing and turning. 

"Research suggests that it does not offer the body any advantages over getting a steady dose of shut-eye every night," said Dr. Ballehr. Remember, your body is busy at rest, and it's designed to sleep when the sun goes down. 

"It's during this time it repairs itself so one can arise feeling renewed," added Dr. Ballehr.

According to the National Sleep Foundation, adults between 18–64 need seven to nine hours of sleep per night. Also, older adults need seven to eight hours, and children and adolescents require even more sleep.

Aim for the right amount for your age group, and be as consistent as possible. Turning in and waking up at roughly the same time every day is healthier than an all-over-the-place sleep schedule.

Dial Back Stress

Unchecked stress, anxiety, worry, and panic pack have many negative health effects. And suppressing the immune system is one of them, said Dr. Chee.

Plus, "stress can increase the leakiness of the gut and can help drive inflammation and imbalance in the microbiome," Marvin Singh, MD, author of An Integrative Gastroenterologist's Guide to Gut Health & Longevity, told Health. 

Prolonged stress also drives up levels of the hormones cortisol and adrenaline. Eventually, too much of those hormones can inflict damage on the body.

You can take small steps to help chill and unwind, including:

• Meditating
• Catching up with a friend
• Being in nature
• Completing a stress-busting workout

Excessive social media usage might increase your stress and anxiety. Still, screen time watching a movie you love or a binge session of your favorite TV show can help take your mind off things.

Practice Proper Hygiene

When it comes to keeping your immune system strong, proper handwashing is one of the most important things. But if you can't get to soap and water, hand sanitizer is the next best thing. 

Wash Your Hands

"Washing your hands is an extraordinarily good way of helping one from getting sick," advised Dr. Mainardi. 

Plain old soap and water are all you need. It's important to scrub up for at least 20 seconds—the length of singing "Happy Birthday" twice. Per the CDC, that's the minimum time needed to significantly reduce the number of microorganisms on your skin.

But no matter how good your handwashing skills are, they won't help prevent infection unless you know when to scrub up. 

"You should do so before and after any type of risky exposure," said Dr. Ballehr. 

In other words, that includes after using the restroom, sneezing, or coughing. Also, wash your hands before you prepare food, after caring for a sick loved one, treating a wound, or touching any publicly used door handles, knobs, switches, or surfaces, added Dr. Ballehr. 

And if your hands are prone to dry skin, the right moisturizer can help.

Use the Right Hand Sanitizer

If you don't have access to soap and water, hand sanitizer can help kill most microorganisms. Just be sure to take a peek at the alcohol percentage first. Alcohol is the active ingredient working to kill viruses and bacteria. The CDC recommends using hand sanitizer with an alcohol percentage greater than 60%.

A Quick Review

You may be unable to avoid viruses and bacteria that spread the common cold and flu entirely. But you can avoid them as best you can by strengthening your immune system. Focusing on nutrition, hygiene, and other health habits is the key to doing so. 

These simple immune-boosting habits can help you steer clear of some infections. Others can supercharge your immune system, so you can get better quickly if you get sick.