The idea of boosting your immunity is enticing, but the ability to do so has proved elusive for several reasons. 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, 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.
Immune system and age
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-19 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.
Here are 8 tips to strengthen your immunity naturally.
1. Get enough sleep
Sleep and immunity are closely tied.
In fact, inadequate or poor quality sleep is linked to a higher susceptibility to sickness. In a study in 164 healthy adults, those who slept fewer than 6 hours each night were more likely to catch a cold than those who slept 6 hours or more each night. Getting adequate rest may strengthen your natural immunity. Also, you may sleep more when sick to allow your immune system to better fight the illness.
Adults should aim to get 7 or more hours of sleep each night, while teens need 8–10 hours and younger children and infants up to 14 hours.
If you’re having trouble sleeping, try limiting screen time for an hour before bed, as the blue light emitted from your phone, TV, and computer may disrupt your circadian rhythm, or your body’s natural wake-sleep cycle.
Other sleep hygiene tips include sleeping in a completely dark room or using a sleep mask, going to bed at the same time every night, and exercising regularly.
2. Eat more whole plant foods
Whole plant foods like fruits, vegetables, nuts, seeds, and legumes are rich in nutrients and antioxidants that may give you an upper hand against harmful pathogens.
The antioxidants in these foods help decrease inflammation by combatting unstable compounds called free radicals, which can cause inflammation when they build up in your body in high levels. Chronic inflammation is linked to numerous health conditions, including heart disease, Alzheimer’s, and certain cancers. Meanwhile, the fiber in plant foods feeds your gut microbiome, or the community of healthy bacteria in your gut. A robust gut microbiome can improve your immunity and help keep harmful pathogens from entering your body via your digestive tract. Furthermore, fruits and vegetables are rich in nutrients like vitamin C, which may reduce the duration of the common cold.
3. Eat more healthy fats
Healthy fats, like those found in olive oil and salmon, may boost your body’s immune response to pathogens by decreasing inflammation. Although low-level inflammation is a normal response to stress or injury, chronic inflammation can suppress your immune system. Olive oil, which is highly anti-inflammatory, is linked to a decreased risk of chronic diseases like heart disease and type 2 diabetes. Plus, its anti-inflammatory properties may help your body fight off harmful disease-causing bacteria and viruses. Omega-3 fatty acids, such as those in salmon and chia seeds, fight inflammation as well.
4. Eat more fermented foods or take a probiotic supplement
Fermented foods are rich in beneficial bacteria called probiotics, which populate your digestive tract. These foods include yogurt, sauerkraut, kimchi, kefir, and natto. Research suggests that a flourishing network of gut bacteria can help your immune cells differentiate between normal, healthy cells and harmful invader organisms. In a 3-month study in 126 children, those who drank just 2.4 ounces (70 mL) of fermented milk daily had about 20% fewer childhood infectious diseases, compared with a control group. If you don’t regularly eat fermented foods, probiotic supplements are another option. In a 28-day study in 152 people infected with rhinovirus, those who supplemented with probiotic Bifidobacterium animalis had a stronger immune response and lower levels of the virus in their nasal mucus than a control group.
5. Limit added sugars
Emerging research suggests that added sugars and refined carbs may contribute disproportionately to overweight and obesity. Obesity may likewise increase your risk of getting sick. According to an observational study in around 1,000 people, people with obesity who were administered the flu vaccine were twice as likely to still get the flu than individuals without obesity who received the vaccine. Curbing your sugar intake can decrease inflammation and aid weight loss, thus reducing your risk of chronic health conditions like type 2 diabetes and heart disease. Given that obesity, type 2 diabetes, and heart disease can all weaken your immune system, limiting added sugars is an important part of an immune-boosting diet. You should strive to limit your sugar intake to less than 5% of your daily calories. This equals about 2 tablespoons (25 grams) of sugar for someone on a 2,000-calorie diet.
6. Engage in moderate exercise
Although prolonged intense exercise can suppress your immune system, moderate exercise can give it a boost. Studies indicate that even a single session of moderate exercise can boost the effectiveness of vaccines in people with compromised immune systems. What’s more, regular, moderate exercise may reduce inflammation and help your immune cells regenerate regularly.
Examples of moderate exercise include brisk walking, steady bicycling, jogging, swimming, and light hiking. Most people should aim for at least 150 minutes of moderate exercise per week. Physical activity isn't just for building muscles and helping yourself de-stress — it's also an important part of being healthy and supporting a healthy immune system. One way exercise may improve immune function is by boosting your overall circulation, making it easier for immune cells and other infection-fighting molecules to travel more easily throughout your body. In fact, studies have shown that engaging in as little as 30 minutes of moderate-to-vigorous exercise every day helps stimulate your immune system. This means it's important to focus on staying active and getting regular exercise.
7. Stay hydrated
Hydration doesn’t necessarily protect you from germs and viruses, but preventing dehydration is important to your overall health. Dehydration can cause headaches and hinder your physical performance, focus, mood, digestion, and heart and kidney function. These complications can increase your susceptibility to illness. To prevent dehydration, you should drink enough fluid daily to make your urine pale yellow. Water is recommended because it’s free of calories, additives, and sugar. While tea and juice are also hydrating, it’s best to limit your intake of fruit juice and sweetened tea because of their high sugar contents. As a general guideline, you should drink when you’re thirsty and stop when you’re no longer thirsty. You may need more fluids if you exercise intensely, work outside, or live in a hot climate. It’s important to note that older adults begin to lose the urge to drink, as their bodies do not signal thirst adequately. Older adults need to drink regularly even if they do not feel thirsty.
Water plays many important roles in your body, including supporting your immune system. A fluid in your circulatory system called lymph, which carries important infection-fighting immune cells around your body, is largely made up of water. Being dehydrated slows down the movement of lymph, sometimes leading to an impaired immune system.
Even if you're not exercising or sweating, you're constantly losing water through your breath, as well as through your urine and bowel movements. To help support your immune system, be sure you're replacing the water you lose with water you can use — which starts with knowing how much water you really need.
8. Manage your stress levels
Relieving stress and anxiety is key to immune health. Long-term stress promotes inflammation, as well as imbalances in immune cell function. In particular, prolonged psychological stress can suppress the immune response in children. Activities that may help you manage your stress include meditation, exercise, journaling, yoga, and other mindfulness practices. You may also benefit from seeing a licensed counselor or therapist, whether virtually or in person.
15 Foods That Boost the Immune System
1. Citrus fruits
Most people turn straight to vitamin C after they’ve caught a cold. That’s because it helps build up your immune system. Vitamin C is thought to increase the production of white blood cells, which are key to fighting infections. Almost all citrus fruits are high in vitamin C. With such a variety to choose from, it’s easy to add a squeeze of this vitamin to any meal.
Popular citrus fruits include:
Because your body doesn’t produce or store it, you need daily vitamin C for continued health.
2. Red bell peppers
If you think citrus fruits have the most vitamin C of any fruit or vegetable, think again. Ounce for ounce, red bell peppers contain almost 3 times as much vitamin C as a Florida orange. They’re also a rich source of beta carotene.
Besides boosting your immune system, vitamin C may help you maintain healthy skin. Beta carotene, which your body converts into vitamin A, helps keep your eyes and skin healthy.
Broccoli is supercharged with vitamins and minerals. Packed with vitamins A, C, and E, as well as fiber and many other antioxidants, broccoli is one of the healthiest vegetables you can put on your plate. The key to keeping its power intact is to cook it as little as possible — or better yet, not at all. Research has shown that steaming is the best way to keep more nutrients in the food.
Garlic is found in almost every cuisine in the world. It adds a little zing to food and it’s a must-have for your health. Early civilizations recognized its value in fighting infections. Garlic may also slow down hardening of the arteries, and there’s weak evidence that it helps lower blood pressure. Garlic’s immune-boosting properties seem to come from a heavy concentration of sulfur-containing compounds, such as allicin.
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. Ginger may help with nausea as well. While it’s used in many sweet desserts, ginger packs some heat in the form of gingerol, a relative of capsaicin.
Ginger may also decrease chronic pain and might even possess cholesterol-lowering properties.
Spinach made our list not just because it’s rich in vitamin C — it’s also packed with numerous antioxidants and beta carotene, which may both increase the infection-fighting ability of our immune systems. Similar to broccoli, spinach is healthiest when it’s 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.
Look for yogurts that have the phrase “live and active cultures” printed on the label, like Greek yogurt. 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. Vitamin D helps regulate the immune system and is thought to boost our body’s natural defenses against diseases. Clinical trials are even in the works to study its possible effects on COVID-19.
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. It’s a fat-soluble vitamin, which means it requires the presence of fat to be absorbed properly. 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. A half-cup serving of almonds, which is about 46 whole, shelled almonds, provides around 100 percent of the recommended daily amount.
9. Sunflower seeds
Sunflower seeds are full of nutrients, including phosphorous, magnesium, and vitamins B-6 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 incredibly 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) and an antiviral. More research is needed.
11. Green tea
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. In studies, EGCG has been shown to enhance immune function. 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.
Green tea is also a good source of the amino acid L-theanine. L-theanine may aid in the production of germ-fighting compounds in your T cells.
Papaya is another fruit loaded with vitamin C. You can find double the daily recommended amount of vitamin C in a single medium fruit. 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 naturally full of a ton of essential nutrients, including folate, potassium, vitamin K, and vitamin C. Vitamin C boosts the white blood cells to fight infection, while kiwi’s other nutrients keep the rest of your body functioning properly.
When you’re sick and you reach for chicken soup, it’s more than just the placebo effect that makes you feel better. The soup may help lower inflammation, which could improve symptoms of a cold. Poultry, such as chicken and turkey, is high in vitamin B-6. About 3 ounces of light turkey or chicken meat contains nearly one-third of your daily recommended amount of B-6.
Vitamin B-6 is an important player in many of the chemical reactions that happen in the body. It’s also vital to the formation of new and healthy red blood cells. Stock or broth made by boiling chicken bones contains gelatin, chondroitin, and other nutrients helpful for gut healing and immunity.
Shellfish isn’t what jumps to mind for many who are trying to boost their immune system, but some types of shellfish are packed with zinc. Zinc doesn’t get as much attention as many other vitamins and minerals, but our bodies need it so that our immune cells can function as intended.
Varieties of shellfish that are high in zinc include: