Which foods boost the immune system?

Can foods boost the immune system? If this thought has ever crossed your mind, you’re not alone. When it comes to preventing infections, we roughly know the drill. Wash your hands thoroughly. Sanitize surfaces. Stay home if you’re not feeling well. But many of us remain unsure as to what to eat to prevent our bodies from constantly getting ill. 

It’s easy to fall prey to marketing gimmicks deployed by food brands. After all, it’s comforting to think that there is a single superfood or supplement out there that can supercharge our immunity and solve all of our health problems. But in reality, it’s way more complicated than that. 

It’s definitely true that certain vitamins can provide a boost to our immune system. But at the same time, our bodies are complex machines with sophisticated needs. Sticking to a healthy, balanced diet may be much more beneficial to our health than popping vitamin supplements. So if you’re interested to know whether foods can actually boost the immune system, keep reading. Here, we’ll discuss what and how to eat in order to keep yourself fit and healthy.

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Which foods boost the immune system?

Fruits

Fruits are one of the most nutrient-dense food groups. Packed with vitamins, minerals and many different biologically active compounds, they can provide a great boost to your immune defenses. Every type of fruit has something to offer your health and wellbeing. To get the most benefit, make sure to include a whole rainbow of plants in your diet. 

Having said this, certain fruits may have stronger immunoprotective properties than others. Citrus fruits, such as oranges, lemons and limes, are a perfect example of foods that can boost the immune system. They’re widely known to be one of the best sources of vitamin C, a nutrient routinely used to treat viral and bacterial infections. But that’s not the only compound that makes them so effective. Citrus fruits are also rich in flavonoids, particularly hesperidin. Hesperidin is a powerful antioxidant that fights inflammation and respiratory viruses. According to an article in Frontiers of Immunology, regular consumption of citrus fruit juices can increase the number of infection-fighting white blood cells and decrease the levels of inflammatory markers in the body. 

Another family of fruit that’s been shown to promote a healthier immune system is berries. Multiple studies have shown that berries contain antioxidant, antimutagenic, antimicrobial, anti-inflammatory, and neuroprotective properties. 

Vegetables

If you want to boost your immune system, one of the best ways is to include more vegetables in your diet. Similarly to fruits, this food group provides a hefty dose of vitamins, minerals and phytonutrients. They’re also a great source of fiber and prebiotics – compounds that feed the good bacteria living in our gut. And keeping our gut health in check will in turn have a beneficial impact on our immune responses. To maximize your chances of staying free from infection, include many different types of vegetables in your diet. 

Red bell and chili peppers are a great source of vitamin C, almost on par with citrus fruits. They also contain an alkaloid called capsaicin. According to a review published in Critical Reviews in Food Science and Nutrition, capsaicin possesses strong antioxidant and anti-inflammatory properties and as such, has the potential clinical value for pain relief, cancer prevention and weight loss.

Cruciferous vegetables, such as broccoli, cabbage, cauliflower and brussel sprouts, can also contribute to a stronger immune system. They contain high levels of vitamin C and E, as well as compounds called glucosinolates. As described in the Molecules journal, glucosinolates have been shown to be protective against many different types of cancer, including breast, brain, blood, bone, colon, gastric, liver, lung, oral, pancreatic and prostate. 

Broccoli is another great example of a food that can boost your immune system. Apart from containing many vitamins, polyphenols and glucosinolates, it’s also a great source of substances called sulforaphane and quercetin. According to a review published in Phytochemistry Reviews, sulforaphane is highly involved in detoxification and neutralization of chemical carcinogens and free radicals. Quercetin also displays powerful antioxidant, anti-allergic and antiviral properties.

Special attention should also be given to green leafy vegetables, such as kale, lettuce and spinach. Spinach is considered to be one of the healthiest vegetables. Multiple studies have demonstrated its antioxidant, anti-cancer, anti-inflammatory, hypoglycemic, and cholesterol-lowering abilities. It provides a solid dose of vitamins, minerals and phytonutrients, including a carotenoid called lutein. As suggested in a review in the Food and Chemical Toxicology journal, lutein has been shown to stimulate the production of antibodies and fight bacterial infections. 

Mushrooms

There’s been a growing interest in the immune-strengthening properties of mushrooms. This food group provides a good deal of selenium and B vitamins, both of which have an important role in our immune health. Furthermore, mushrooms contain a range of highly specific immunomodulatory and anti-cancer proteins, as described in the Journal of Autoimmunity. 

Many types of mushrooms are beneficial to our health, but recently the attention has been directed particularly at shiitake mushrooms. According to the Journal of the American College of Nutrition, regular consumption of shiitake significantly improves white blood cell and antibody production in the body.      

Fermented foods

Fermented food and drink has a long history. They were among the first processed food products consumed by humans – and for many good reasons. The fermentation process improves the shelf life, safety and flavor of foods like yogurt, pickles, sauerkraut or kimchi. It also enhances their nutritional properties. 

Many fermented foods contain strains of beneficial live bacteria, often referred to as probiotics. Probiotics can stimulate immune system function through enhancing natural killer cell toxicity, regulating the production of pro-inflammatory cytokines, and increasing white blood cell count, according to a study in the Food Control journal. 

Seafood

When it comes to foods that boost the immune system, seafood may not be the first thing to cross your mind. But this food group has a lot to offer. Oily fish, for example, is a great source of omega-3 fatty acids, melatonin, tryptophan and polyamines. According to a review published in Frontiers in Nutrition, regular fish consumption can lead to better gut health and a reduced risk of developing inflammatory conditions like rheumatoid arthritis and psoriasis. 

Shellfish – including shrimp, lobsters, oysters, mussels, scallops, clams, crabs, krill and snails – also contain significant quantities of immune-stimulating bioactive peptides, antioxidants, vitamins and minerals. In fact, oysters are one of the best sources of zinc, which is linked to immune health.

Spices and condiments

Spices and condiments are great for increasing the flavor of dishes, but that’s not the only thing they’re useful for.

Garlic is a great example of a food that can boost the immune system. According to a meta-analysis published in the Journal of Nutrition, garlic appears to stimulate the production and regulate the functioning of white blood cells, cytokines and immunoglobulins. Regular consumption can contribute to the treatment and prevention of respiratory infections, gastric ulcer, and even cancer. 

Ginger is another example. According to the International Journal of Preventive Medicine, ginger has a strong anti-inflammatory, antioxidative and anticancer potential. 

What’s more, black pepper may also be able to boost the immune system. Due to its antibacterial properties, it’s long been used as a food preservative. It contains a compound called piperine, which according to a review published in the Phytotherapy Research journal, displays numerous health benefits. 

In the last several years, researchers have also been extensively studying the immunomodulatory properties of turmeric. Recent studies have demonstrated that curcumin – the main active ingredient of turmeric – shows antioxidant, anti-inflammatory, and immune-regulatory properties and can reduce the risk of several types of cancers.

• Related: How to boost your immune system naturally

How to integrate immune-boosting foods into a balanced diet

Many foods have the ability to boost the immune system, but how can you make sure you’re including them in your diet? 

Firstly, make sure to focus on eating wholefoods and cooking from scratch. Also, try to avoid highly processed foods – items such as packaged bread, microwave meals and breakfast cereals may appear healthy, but they tend to be largely devoid of immune-supporting nutrients. If you feel peckish, try to snack on citrus fruit and berries. When it comes to larger meals, try to add a solid portion of vegetables, mushrooms, fish, shellfish and fermented foods to your plate. Experiment with spices and condiments too.

It’s also good to make sure that your cooking processes don’t destroy immune-boosting nutrients. For example, fruits and vegetables are sensitive to heat, so don’t overcook them. Instead, stick to steaming and gentle processing. According to an article published in Food Science and Biotechnology, prolonged boiling, frying and baking may result in reduced levels of vitamin C, A, D, E and K, as well as minerals like potassium, magnesium, sodium and calcium. In fact, broccoli may lose up to 50% or more of its vitamin C when boiled. 

If you’re not a fan of the taste of turmeric or mushrooms, consider dietary supplements. Many brands offer good quality extracts made from immune-boosting foods. It's also relatively easy to top up on probiotics in the form of tablets or capsules – for best results, look for quality products with multiple different bacteria strains. If you are thinking of changing your supplement routine, however, it’s best to consult your doctor first.

Other ways to boost the immune system

Increase your physical activity levels

There’s no doubt that being more active is one of the best things you can do for your physical health and mental wellbeing. It’s also a great way to boost your immune system. According to an article published in the Nutrition journal, exercise intensity and duration are closely linked to the functioning of multiple immune system components. 

Researchers from the Sports Medicine journal also pulled together the results of multiple studies and concluded that higher levels of habitual physical activity is associated with a 31% lower risk of contracting an infectious disease and a 37% reduced risk of dying from it. 

Prioritize quality sleep

Maintaining good sleep hygiene can make a huge difference to your quality of life. But getting enough sleep is also an important factor in immunity. A good snooze helps to balance the levels of hormones and cytokines that are responsible for regulating the inflammatory responses in the body, as described by a study in the Annals of the New York Academy of Sciences. 

Some animal studies have also shown that interactions between immune signaling molecules and brain neurochemicals increase significantly during infection, indicating that we tend to sleep differently when we are sick. Researchers suggested that during infection, these sleep alterations help our body to recover faster. 

Keep your stress levels under control

Short bouts of stress can help us to survive dangerous situations. But when that stress becomes chronic, it can have a serious impact on our physical health. 

In an article published in the Brain and Behavior journal, researchers speculate that chronic stress severely disrupts immune system signaling and increases the levels of inflammation in the body. There’s also a growing body of evidence to suggest that stress-reducing interventions have a direct impact on our susceptibility to infections. For example, multiple studies have shown that engaging in mindfulness meditation may result in decreased markers of inflammation and improved immune signaling.