If you suspect your diet is not providing you with all your micronutrient needs — maybe, for instance, you don't like vegetables — taking a daily multivitamin and mineral supplement may bring other health benefits, beyond any possibly beneficial effects on the immune system.

Taking megadoses of a single vitamin does not. More is not necessarily better. Walk into a store, and you will find bottles of pills and herbal preparations that claim to "support immunity" or otherwise boost the health of your immune system.

Although some preparations have been found to alter some components of immune function, thus far there is no evidence that they actually bolster immunity to the point where you are better protected against infection and disease.

Demonstrating whether an herb — or any substance, for that matter — can enhance immunity is, as yet, a highly complicated matter.

Scientists don't know, for example, whether an herb that seems to raise the levels of antibodies in the blood is actually doing anything beneficial for overall immunity. Modern medicine has come to appreciate the closely linked relationship of mind and body.

A wide variety of maladies, including stomach upset, hives, and even heart disease, are linked to the effects of emotional stress. Despite the challenges, scientists are actively studying the relationship between stress and immune function.

For one thing, stress is difficult to define. What may appear to be a stressful situation for one person is not for another. When people are exposed to situations they regard as stressful, it is difficult for them to measure how much stress they feel, and difficult for the scientist to know if a person's subjective impression of the amount of stress is accurate.

The scientist can only measure things that may reflect stress, such as the number of times the heart beats each minute, but such measures also may reflect other factors. Most scientists studying the relationship of stress and immune function, however, do not study a sudden, short-lived stressor; rather, they try to study more constant and frequent stressors known as chronic stress, such as that caused by relationships with family, friends, and co-workers, or sustained challenges to perform well at one's work.

Some scientists are investigating whether ongoing stress takes a toll on the immune system. But it is hard to perform what scientists call "controlled experiments" in human beings. In a controlled experiment, the scientist can change one and only one factor, such as the amount of a particular chemical, and then measure the effect of that change on some other measurable phenomenon, such as the amount of antibodies produced by a particular type of immune system cell when it is exposed to the chemical.

In a living animal, and especially in a human being, that kind of control is just not possible, since there are so many other things happening to the animal or person at the time that measurements are being taken. Despite these inevitable difficulties in measuring the relationship of stress to immunity, scientists are making progress.

Almost every mother has said it: "Wear a jacket or you'll catch a cold! Probably not, exposure to moderate cold temperatures doesn't increase your susceptibility to infection.

There are two reasons why winter is "cold and flu season. Also the influenza virus stays airborne longer when air is cold and less humid. But researchers remain interested in this question in different populations. Some experiments with mice suggest that cold exposure might reduce the ability to cope with infection.

But what about humans? Scientists have performed experiments in which volunteers were briefly dunked in cold water or spent short periods of time naked in subfreezing temperatures.

They've studied people who lived in Antarctica and those on expeditions in the Canadian Rockies. The results have been mixed. For example, researchers documented an increase in upper respiratory infections in competitive cross-country skiers who exercise vigorously in the cold, but whether these infections are due to the cold or other factors — such as the intense exercise or the dryness of the air — is not known.

A group of Canadian researchers that has reviewed hundreds of medical studies on the subject and conducted some of its own research concludes that there's no need to worry about moderate cold exposure — it has no detrimental effect on the human immune system.

Should you bundle up when it's cold outside? The answer is "yes" if you're uncomfortable, or if you're going to be outdoors for an extended period where such problems as frostbite and hypothermia are a risk. But don't worry about immunity. Regular exercise is one of the pillars of healthy living.

It improves cardiovascular health, lowers blood pressure, helps control body weight, and protects against a variety of diseases. But does it help to boost your immune system naturally and keep it healthy?

Just like a healthy diet, exercise can contribute to general good health and therefore to a healthy immune system. As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date of last review or update on all articles.

No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.

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Photos courtesy of Michael N. Starnbach, Ph. Every part of your body, including your immune system, functions better when protected from environmental assaults and bolstered by healthy-living strategies such as these: Don't smoke. Eat a diet high in fruits and vegetables. Exercise regularly.

Maintain a healthy weight. If you drink alcohol, drink only in moderation. Get adequate sleep. Take steps to avoid infection , such as washing your hands frequently and cooking meats thoroughly. Try to minimize stress. Keep current with all recommended vaccines.

Vaccines prime your immune system to fight off infections before they take hold in your body. Increase immunity the healthy way Many products on store shelves claim to boost or support immunity.

Immune system and age As we age, our immune response capability becomes reduced, which in turn contributes to more infections and more cancer. 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. The body needs zinc to support the immune system, said Dr. Additionally, zinc helps with wound healing. The recommended amount of zinc is 13 milligrams for adult men and 9.

Typically, you can get enough zinc from foods like:. Still, it may help to consider taking a zinc supplement after talking to a healthcare provider, suggested Dr.

A healthcare provider may test your blood to see if you aren't getting enough zinc from your diet. Hydration is key to a healthy body and immune system. Water serves several essential functions in the body, including:. 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.

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.

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 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.

One study published in in the Journal of Sports and Health Science described the following benefits of moderate to vigorous exercise:. 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 minutes of moderate-intensity aerobic activity weekly.

Or, if you prefer vigorous exercise, the CDC recommends 75 minutes at that intensity. A to 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. For example, in one study published in in Nature and Science of Sleep , researchers found disrupted sleep caused serious health ramifications, including:.

Also, don't assume you can just catch up on sleep after a night or two of staying up late or tossing and turning. Remember, your body is busy at rest, and it's designed to sleep when the sun goes down.

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.

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

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. 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. 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. And if your hands are prone to dry skin, the right moisturizer can help. 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. 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. Dietary supplements are minimally regulated by the FDA and may or may not be suitable for you. The effects of supplements vary from person to person and depend on many variables, including type, dosage, frequency of use, and interactions with current medications.

Please speak with your healthcare provider or pharmacist before starting any supplements. Minich DM. A Review of the Science of Colorful, Plant-Based Food and Practical Strategies for "Eating the Rainbow" [published correction appears in J Nutr Metab.

J Nutr Metab. Kapoor R, Sharma B, Kanwar SS. Antiviral phytochemicals: an overview. Biochem Physiol. Calder PC. Omega-3 fatty acids and inflammatory processes: from molecules to man.

Biochem Soc Trans. Stromsnes K, Correas AG, Lehmann J, Gambini J, Olaso-Gonzalez G. Anti-Inflammatory Properties of Diet: Role in Healthy Aging.

Stadlbauer V. Immunosuppression and probiotics: are they effective and safe? Benef Microbes. National Institutes of Health. Office of Dietary Supplements. Geological Survey.