As we transition into fall we’re confronted with the same seasonal changes year after year. The temperatures drop, pumpkin spice everything appears on store shelves, kids go back to school, cold-weather boots along with hats and scarves come out of storage, leaves change color, apple cider perfumes the air, and we tend to move indoors en masse for long stretches of time.

When more bodies share an enclosed space, those same bodies tend to share more germs. If you have a strong and healthy body, and therefore a strong immune system, you may not notice it’s the start of cold and flu season. If your body isn’t resilient enough to fight off the onslaught, you may start suffering from a procession of colds and viruses that will ride you through fall, into winter and spring.

The good news is, there are things you can do to prevent this from happening. As long as your body’s system of defense is running smoothly, you don’t even notice the cacophony of sneezing and coughs going on around you. Only when something goes wrong do you realize you’ve got a gap in your defenses and the snotty suffering begins.

Here is everything you should know about how your immune system keeps you healthy—and the best ways you can support it as it fights the good fight on your behalf.


The immune system guards your body like an army from harmful incursions from your environment. Your immune system is essential for your survival. Your immune system is a vast network of organs, proteins, and cells—like your skin, bone marrow, blood, and mucosal tissue—that join forces to distinguish healthy cells from not-so-healthy ones. Aside from the nervous system, it is the most complex system in your entire body.

Different groups of cells work together and form alliances against just about any pathogen (germ) you’re likely to come across. But illness can occur if the performance of your immune system is compromised, if a pathogen is especially aggressive, or if your body comes across a pathogen it has not come into contact with before.

The main tasks of the body’s immune system are:

Neutralizing pathogens like bacteria, viruses, parasites or fungi that have entered the body, and removing them from the body.

Recognizing and neutralizing harmful substances from the environment (environmental pollutants, pesticides in the food you eat, chemicals or heavy metals introduced into the body, etc.)

Fighting against the body’s own cells that have changed due to an illness, for example cancer cells.

When a germ makes its way into your body, your immune system receives signals that something isn’t quite right. From there, it responds by sending white blood cells (or immune cells)—your body’s frontline defense—to attack and destroy anything that it interprets as risky or dangerous.

For our immune system to effectively protect us it has to be able to differentiate between “self” and “non-self” cells, organisms, and substances.

The immune system is activated by many “non-self” substances. These are called antigens. The proteins on the surfaces of bacteria, fungi and viruses, for example, are all antigens. These antigens are what helps our immune system build immunity.

When the antigens on a virus, for example, binds to special receptors on our defense cells, a series of cell processes is started. The immune systems recalls stored “memories” about how it defeated that antigen before and it’s more quickly ready to defend us.

The body’s own cells have surface proteins similar to the ones on bacteria, fungi and viruses as well. However, our immune system does not fight against them, because it learned earlier to identify specifically these cell proteins as “self.”

If the immune system identifies the cells of its own body as “non-self,” it is also called an autoimmune reaction.


There are two main parts of the immune system: the innate (and evolutionarily older) system and the adaptive immune system.

The innate immune system, or nonspecific immune system, provides a general defense again pathogens. It’s also called the nonspecific immune system and works mostly at the level of immune cells like scavenger cells or killer cells, which fight mostly against bacterial infections.

Then we have the adaptive immune system. It’s also called a learned defense or specific immune response. Think of this as your body’s special forces units. In this system antibodies target very specific pathogens that the body has already had contact with. This adaptive immune system constantly learns and adapts to new and varying pathogens so your body can fight against bacteria, fungi or viruses that change over time.

They seem like separate forces against illness, but neither of your immune systems works independently of one another. They work together, and are closely connected in their reaction to pathogens and harmful substances.


The idea of boosting your immunity is paved with good intentions. Who wants a weak immune system? Nobody. The problem is that there is no magic pill to a strong immune system. The immune system is precisely that — a system, not a single entity. To function well, it requires balance and harmony. There is still much that researchers don’t know about the intricacies and interconnectedness of the immune response. For now, science has yet to find a concrete and verifiable single way to strengthen your immune response. All is not lost however.


Following general good-health guidelines is the single best step you can take toward naturally keeping your immune system strong and healthy. Every part of your body, including your immune system, functions better when protected from environmental assaults and is bolstered by healthy-living strategies.


Smoking, first-hand or second-hand, cigarettes or marijuana, undermines basic immune defenses. Your body has to pull resources from the immune system forces to help mitigate and remove environmental pollutants from the smoke you’ve lined your lungs with. These pollutants, the inflammation to the inside of your lungs you’ve caused, and the decrease in available immune cells to fight infection raises the risk of bronchitis, pneumonia and viral infection in everyone, and especially middle ear infections in kids.


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.

Having a varied diet can be difficult but it’s definitely worth trying to do and will keep you much healthier in the long run. An eating plan rich in fruits, veggies, whole grains, and lean proteins will defend your body against most harmful germs.

Eating more fruits and vegetables, which are rich in nutrients like vitamins C and E, plus beta-carotene and zinc is going to strengthen and fortify your body. Seek a wide variety of brightly colored fruits and vegetables, including berries, citrus fruits, kiwi, apples, red grapes, kale, onions, spinach, sweet potatoes, and carrots. Remember, the brighter the color of your fresh food, the more antioxidants. These work directly in your body to remove free radicals (environmental pollutants) and will free up your immune cells to fight pathogens.

Other foods particularly good for your immune system include fresh garlic, which may help fight viruses and bacteria, and old-fashioned chicken soup. If you do come down with a cold or the flu, a bowl of chicken soup can help you get well faster science has shown.

Some mushroom varieties — such as shiitake — may also help your immune system. More research needs to be done on the specifics of mushroom and improved immunity cell production, but the science so far is supportive of their role. Try to find a way to eat more mushrooms, more often, for a more well-rounded diet that’s going to boost your immune system.

Sometimes even your efforts at healthy eating can wind up backfiring. People who are on any sort of extreme diet that’s very low carb or very calorically restricted tend to get sick more often. This may be because these diets are lacking in certain vitamins and minerals like zinc, selenium, and magnesium that you get from eating well-balanced meals. You can have a greater risk of getting sick even from following popular diets like Paleo, South Beach, and Atkins or even doing frequent juice cleanses. Vegans in particular are susceptible to iron, vitamin B, zinc and calcium deficiencies and often need supplementation.

If you suspect your diet is not providing you with all of your micronutrient needs taking a daily multivitamin and mineral supplement may bring other health benefits, beyond any possibly beneficial effects on the immune system.


Eating or drinking too much sugar curbs immune system cells that attack bacteria. This effect lasts for at least a few hours after downing a couple of sugary drinks. If you add sugar to your coffee in the morning, have a sugar-filled drink with lunch, and then eat dessert after dinner you’ve just successfully suppressed your immune system for the entire day. Do this day after day and you will assuredly face illness.


Although the science and understanding behind the microbiome is relatively new, it’s also abundantly clear. Your microbiome creates and supports 90% of your immune system. It makes sense. After all, the largest percentage of pathogens and environmental pollutants coming into your body come in through your gut.

To feed your microbiome (the bacteria, fungi and viruses that live in your digestive system and keep you healthy and alive) think about eating foods with live and active cultures.

Fermented foods and drinks like kombucha, kimchi, and saur kraut may offer additional benefit to your microbiome and overall health than regular food.

A slew of new data has recently come out saying that probiotics may also serve to boost our immune systems. Consider taking a daily probiotic supplement to keep your gut health in tip-top form.

Of course probiotics are completely useless unless you feed them.  Probiotics eat prebiotics, which means you should be eating prebiotics as well to keep a healthy microbe balance. Prebiotics are in foods such as whole grains, bananas, leafy greens, onions, garlic, leeks, and Jerusalem artichokes.


Not getting enough rest, straying from your regular diet, and being out of your routine can take a toll on your immune system.

Try to maintain as much of a regular routine as possible even when taking a trip. If you do travel here are some tips to keep yourself regular, healthy and strong while on the road.

Since exercise boosts immunity, make sure to move for at least 15 to 20 minutes a day. And try your hardest to eat well; pack your carry-on with healthy, immune-boosting snacks like tangerines, mixed nuts, or even dark chocolate, which is a good source of beneficial magnesium.


Exercising regularly and eating healthy are the most significant factors for your immune system. 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. It has also been proven that people who live more sedentary lifestyles are far more likely to get colds or other infectious diseases.

So try to get regular, moderate exercise daily, like a 30-minute walk.

Exercise can contribute to general good health and therefore to a healthy immune system. It may contribute even more directly by promoting good circulation, which allows the cells and substances of the immune system to move through the body freely and do their job efficiently.

Moderate daily exercise also causes a release of feel-good chemicals in our bodies. Which can help us sleep better. You could check two boxes with one action if you incorporate some form of exercise into your schedule before bed. Increase your circulation, and sleep better. Both of which are boosts to your immune system’s health.


Chronic binge drinking suppresses bone marrow production of red and white blood cells. Over time this hinders your immune system. You are causing your body to create less soldiers in the fight against illness. If you must drink, drink less. Be mindful, also, of the large amounts of sugars found in wines and other drinks.  As we’ve said, sugar also hinders the functionality of your immune system.


You may have noticed you’re more likely to catch a cold or other infection when you’re not getting enough sleep. Although researchers aren’t exactly sure how sleep boosts the immune system, it’s clear that getting enough – usually 7 to 9 hours for an adult – is key for good health.

Not getting enough sleep can lead to higher levels of a stress hormone as well. It may also lead to more inflammation in your body. None of these are helpful when your body is fighting a highly contagious norovirus.

When you’re feeling overwhelmed by your endless to-do list, it can be tempting to skimp on sleep to get everything done. If not prioritizing sleep becomes a habit, however, it can have serious ramifications on your health.

Do your body, and your mind, a favor – get good sleep!


It seems obvious, but bares repeating, you can go a long ways to preventing illness with the simple act of washing your hands.

Wash your hands frequently and cook meats thoroughly.


It’s been said that our western culture has the most expensive pee in the world. For the general, run-of-the-mill person who doesn’t have any illnesses, vitamin supplements aren’t really necessary. The vast majority of nutrients we need we can get from the food we eat, and vitamins can get expensive

But, if you do decide you want to take a vitamin, try taking the recommended daily dose of a general multivitamin. Be careful with individual supplements of vitamin A, D, E, and K, which can be dangerous to humans if taken in high doses. Often more is not better when it comes to vitamins and supplements.

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.

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. No one knows how many cells or what the best mix of cells the immune system needs to function at its optimum level.

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. Stress looks different from person to person, which makes it hard to nail down with a definition or antidote. What may appear to be a stressful situation for one person is not for another.  Despite the challenges, scientists are actively studying the relationship between stress and immune function.

Everyone has stress, it’s just a fact of life. The trouble with stress is that if it drags on for a long time, it can make you more vulnerable to all types of illness, all of the way from colds to serious diseases.

Because of the stress hormones your body creates (cortisol being the big one) and their caustic effects in the body, when they’re present for extended periods of time they can suppress the immune system.

Nobody has a life with zero stress in it, so you can forget about getting rid of stress all together. But there are some ways you can get better at managing it.

Easing stress lowers levels of stress hormone which can also help you sleep better, which also improves immune function.

If you’re in doubt about the connection between stress and illness, consider this. People who meditate regularly may have healthier immune system responses, some studies show. In one experiment, people who meditated over an 8-week period made more antibodies to a flu vaccine than people who didn’t meditate. And they still showed an increased immune system response 4 months later. 4 months!


As we age, our immune response capability becomes reduced, which in turn contributes to more infections and more even cancer.

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, influenza, 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.

Other studies 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.

It is that stem-cell suppressed people, like those who’ve gone through stem cell transplants, or bone marrow transplants, have weaker immune systems and require extraordinary precautions to prevent exposure to pathogens when their bodies are at their most vulnerable.


Despite what the supplement and vitamin industry want us to believe, there is no magic pill (or magic vitamin, herb or supplement) to boost our immune systems. Our immune system is the sum total of a myriad of biological systems from hormonal to the cellular. The best we can do to increase our immune health is to practical healthy lifestyle decisions, minimize our exposure to pathogens, minimize our stress levels, maintain healthy amounts of sleep, and keep our microbiome as healthy as possible.


Harvard Health


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