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.

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Beyond the usual suspects for healthy resolutions. February 15, Helpful ways to strengthen your immune system and fight off disease How can you improve your immune system? What can you do to boost your immune system? 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.

Diet and your immune system Like any fighting force, the immune system army marches on its stomach. Improve immunity with herbs and supplements?

Stress and immune function Modern medicine has come to appreciate the closely linked relationship of mind and body. Does being cold give you a weak immune system? Exercise: Good or bad for immunity?

Cedars-Sinai Blog Can You Really Boost Your Immune System? How your immune system works. Read: Is It a Cold or the Flu? Can you strengthen your immune system? What you can do to protect your immune system. There are some diet and lifestyle factors that influence your immune response.

How to keep from getting sick. Read: Vaccine Fast Facts. Reducing your risk of exposure to COVID coronavirus. Read: Understanding Vitamin D Deficiency. Tags: Expert Advice. Popular Categories. Popular Topics. Women's Health. Expert Advice.

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For now, there are no scientifically proven direct links between lifestyle and enhanced immune function. But that doesn't mean the effects of lifestyle on the immune system aren't intriguing and shouldn't be studied. Researchers are exploring the effects of diet, exercise, age, psychological stress, and other factors on the immune response, both in animals and in humans.

In the meantime, general healthy-living strategies make sense since they likely help immune function and they come with other proven health benefits. Immunity in action. A healthy immune system can defeat invading pathogens as shown above, where two bacteria that cause gonorrhea are no match for the large phagocyte, called a neutrophil, that engulfs and kills them see arrows.

Your first line of defense is to choose a healthy lifestyle. Following general good-health guidelines is the single best step you can take toward naturally keeping your immune system working properly.

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:.

Many products on store shelves claim to boost or support immunity. But the concept of boosting immunity actually makes little sense scientifically.

In fact, boosting the number of cells in your body — immune cells or others — is not necessarily a good thing. For example, athletes who engage in "blood doping" — pumping blood into their systems to boost their number of blood cells and enhance their performance — run the risk of strokes.

Attempting to boost the cells of your immune system is especially complicated because there are so many different kinds of cells in the immune system that respond to so many different microbes in so many ways.

Which cells should you boost, and to what number? So far, scientists do not know the answer. What is known is that the body is continually generating immune cells.

Certainly, it produces many more lymphocytes than it can possibly use. The extra cells remove themselves through a natural process of cell death called apoptosis — some before they see any action, some after the battle is won.

No one knows how many cells or what the best mix of cells the immune system needs to function at its optimum level. As we age, our immune response capability becomes reduced, which in turn contributes to more infections and more cancer. As life expectancy in developed countries has increased, so too has the incidence of age-related conditions.

While some people age healthily, the conclusion of many studies is that, compared with younger people, the elderly are more likely to contract infectious diseases and, even more importantly, more likely to die from them.

Respiratory infections, including, influenza , the COVID virus and particularly pneumonia are a leading cause of death in people over 65 worldwide. No one knows for sure why this happens, but some scientists observe that this increased risk correlates with a decrease in T cells, possibly from the thymus atrophying with age and producing fewer T cells to fight off infection.

Whether this decrease in thymus function explains the drop in T cells or whether other changes play a role is not fully understood. Others are interested in whether the bone marrow becomes less efficient at producing the stem cells that give rise to the cells of the immune system.

A reduction in immune response to infections has been demonstrated by older people's response to vaccines. For example, studies of influenza vaccines have shown that for people over age 65, the vaccine is less effective compared to healthy children over age 2.

But despite the reduction in efficacy, vaccinations for influenza and S. pneumoniae have significantly lowered the rates of sickness and death in older people when compared with no vaccination. There appears to be a connection between nutrition and immunity in the elderly.

A form of malnutrition that is surprisingly common even in affluent countries is known as "micronutrient malnutrition. Older people tend to eat less and often have less variety in their diets. One important question is whether dietary supplements may help older people maintain a healthier immune system.

Older people should discuss this question with their doctor. Like any fighting force, the immune system army marches on its stomach. Healthy immune system warriors need good, regular nourishment.

Scientists have long recognized that people who live in poverty and are malnourished are more vulnerable to infectious diseases. For example, researchers don't know whether any particular dietary factors, such as processed foods or high simple sugar intake, will have adversely affect immune function.

There are still relatively few studies of the effects of nutrition on the immune system of humans. There is some evidence that various micronutrient deficiencies — for example, deficiencies of zinc, selenium, iron, copper, folic acid, and vitamins A, B6, C, and E — alter immune responses in animals, as measured in the test tube.

However, the impact of these immune system changes on the health of animals is less clear, and the effect of similar deficiencies on the human immune response has yet to be assessed. So, what can you do?

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?

Early civilizations recognized its value in fighting infections. Garlic may also slow down hardening of the arteries, and people use it to treat high blood pressure. Ginger is another ingredient many turn to after getting sick. Ginger may help decrease inflammation, which can help reduce a sore throat and inflammatory illnesses.

It may also help with nausea. Ginger may also decrease chronic pain and might even possess cholesterol-lowering properties. Similar to broccoli, spinach is healthiest when cooked as little as possible so that it retains its nutrients. However, light cooking makes it easier to absorb the vitamin A and allows other nutrients to be released from oxalic acid , an antinutrient.

Check out some spinach recipes here. These cultures may stimulate your immune system to help fight diseases. Try to get plain yogurts rather than the kind that are flavored and loaded with sugar. You can sweeten plain yogurt yourself with healthy fruits and a drizzle of honey instead.

Yogurt can also be a great source of vitamin D , so try to select brands fortified with this vitamin. Clinical trials are even in the works to study its possible effects on COVID Research so far suggests that vitamin D deficiency may increase the risk for COVID19 and the severity of disease progression in people with the infection.

Experts therefore believe supplementation may protect people with a vitamin D deficiency. However, there is no evidence that vitamin D can treat a COVID19 infection.

When it comes to preventing and fighting off colds, vitamin E tends to take a backseat to vitamin C. However, this powerful antioxidant is key to a healthy immune system. Nuts, such as almonds , are packed with the vitamin and also have healthy fats.

Adults only need about 15 mg of vitamin E each day. Sunflower seeds are full of nutrients, including phosphorous , magnesium , and vitamins B6 and E.

Vitamin E is important in regulating and maintaining immune system function. Other foods with high amounts of vitamin E include avocados and dark leafy greens. Sunflower seeds are also high in selenium. Just 1 ounce contains nearly half the selenium that the average adult needs daily.

A variety of studies , mostly performed on animals, have looked at its potential to combat viral infections such as swine flu H1N1. You may know turmeric as a key ingredient in many curries. This bright yellow, bitter spice has also been used for years as an anti-inflammatory in treating both osteoarthritis and rheumatoid arthritis.

Research shows that high concentrations of curcumin , which gives turmeric its distinctive color, can help decrease exercise-induced muscle damage. Curcumin has promise as an immune booster based on findings from animal studies with antimicrobial properties.

More research is needed. Both green and black teas are packed with flavonoids , a type of antioxidant. Where green tea really excels is in its levels of epigallocatechin gallate EGCG , another powerful antioxidant. Research has suggested that EGCG may have antiviral properties that support the immune system.

The fermentation process black tea goes through destroys a lot of the EGCG. Green tea, on the other hand, is steamed and not fermented, so the EGCG is preserved. Papayas also have a digestive enzyme called papain that has anti-inflammatory effects.

Papayas have decent amounts of potassium , magnesium, and folate , all of which are beneficial to your overall health. Like papayas, kiwis are a rich source of essential nutrients, including folate, potassium, vitamin K , and vitamin C.

The soup may help lower inflammation, which could improve symptoms of a cold. Poultry, such as chicken and turkey, is high in vitamin B6. About 3 ounces of light turkey or chicken meat contains nearly one-third of your daily recommended amount of B6. Vitamin B6 is an important player in many of the chemical reactions that happen in the body.

Stock or broth made by boiling chicken bones contains gelatin , chondroitin, and other nutrients helpful for gut healing and immunity. Too much zinc can actually inhibit immune system function. You may want to focus on eating a balanced diet with plenty of fresh foods and whole grains, engage in at least minutes of physical activity per week, get enough sleep, manage stress with deep breathing or talk therapy, avoid or quit smoking, and limit alcohol consumption.

Preliminary research suggests vitamin C may be involved in the development and function of white blood cells. It seems vitamin C may improve the reproduction of B- and T-cells , which are important white blood cells for the immune system.

The amount of vitamin C needed for increasing white blood cells may depend on the condition and overall health needs. More research in humans is needed to better understand the link between vitamin C and white blood cells. To raise your white blood cell count , you may want to avoid alcohol and tobacco use, take Omega-3s and zinc, and eat a balanced diet.

For example, a study found that the Mediterranean diet had an effect on the white blood cell counts of adults at risk for cardiovascular disease. Depending on the cause of low white blood cells, you may also need to take medications like myeloid growth factors.

Antiviral foods may include fermented vegetables kimchi , fermented milk yogurt and kefir , herbs oregano, fennel, peppermint, and aloe vera , garlic, ginger, turmeric, black cumin, cinnamon, licorice root, mushrooms, and citrus fruits.

Some foods may boost your immune system while others will help with their antimicrobial properties. This means they may help fight bacteria, viruses, and other pathogens that cause infections.

Examples include herbs and spices oregano , cinnamon , clove , and rosemary , cruciferous vegetables kale and rutabaga , citrus fruits, parsley , and a wide range of other plant-based foods. Eating a variety of vegetables may help you boost your immune system. Red peppers, spinach, and broccoli are good choices, as well as ginger, turmeric, and garlic.