The immune system consists of organs, cells, tissues, and proteins. Together, these carry out a complex group of defense responses and bodily processes that fight off pathogens, which are the viruses, bacteria, and foreign bodies that cause infection or disease.
Having a strong immune system is critical for preventing and fighting disease, especially with the ongoing COVID-19 pandemic still spreading across the world. But there are everyday factors like stress, smoking, lack of sleep, and spending too little time outdoors that can weaken and compromise it.
Unfortunately, no single food or supplement can cure or protect you against viruses like COVID-19 or the flu. Maintaining a healthy immune system, wearing a mask, practicing social distancing, and washing your hands frequently are still the best practices for preventing COVID-19.
But the good news is that there’s evidence that a healthy diet rich in fruit and vegetables can provide your body with essential nutrients that help bolster immunity. Here are 15 immune-boosting foods to help build your body’s defenses against infections. If you’re interested, here’s an immune-boosting supplement to provide additional nutritional support to your system.
1. Citrus Fruit
Citrus fruits are an excellent source of vitamin C – an essential micronutrient that plays a vital role in fighting against disease.
Vitamin C is a powerful antioxidant that can help protect the body against oxidative damage. It also increases the production of white blood cells, which are a key part of the immune response, and your body doesn’t produce or store vitamin C on its own, so you need to get it from foods like citruses or supplements to avoid deficiencies. Nearly all citric foods are high in vitamin C, and though oranges are the most popular, plenty other lesser-known citruses are as healthy and delicious:
- kaffir limes
- finger limes
2. Red bell peppers
Tired of eating citrus fruits for your daily vitamin C fix? Packed with almost three times as much vitamin C as oranges, red bell peppers make for a perfect immune-boosting veggie to add to your diet.
The European Journal of Clinical Nutrition published a paper in April 2020 recommending red bell peppers as part of a healthy quarantine diet because of their content of vitamin A (beta carotene) and C. Fresh, raw bell peppers are also loaded with other important vitamins and minerals, including vitamin E, vitamin K, potassium, and folate. Additionally, red bell peppers have been shown to promote eye and skin health.
Love it or hate it, there’s no denying that broccoli is one of the healthiest vegetables you can eat for overall health.
This nutritional powerhouse is chocked-full of immune-boosting vitamins, minerals, and antioxidants. In fact, a single cup of raw broccoli contains up to 135% of vitamin C’s recommended daily intake. Antioxidants can help prevent the development of various conditions.
Broccoli is also packed with flavonoids, which are potent plant compounds capable of reducing inflammation and protecting against cell damage. Experts recommend eating broccoli raw or as lightly cooked as possible to reap its full benefits. Boiling, microwaving, and frying broccoli have been shown to alter its nutritional profile, especially reducing its vitamin C content.
Elderberries are considered one of the most healing medicinal plants in the world that provide comprehensive immune support. Historically, Native American and European civilizations used these tart fruits to heal wounds, treat infections, and lower fevers.
Evidence shows that supplementing with black elderberry extract can significantly reduce upper respiratory symptoms, like those produced by the cold and flu viruses. For example, in one study of 312 participants, investigators looked at whether taking an elderberry supplement could prevent people from developing a cold or experiencing cold-like symptoms after traveling overseas.
Most people are not aware of the tremendous immune-boosting power of mushrooms. They are packed with a ton of essential vitamins and minerals, carbohydrates, proteins, and potent anti-inflammatory compounds like polysaccharides and polyphenols. However, studies show that cooking mushrooms can destroy many of their anti-inflammatory compounds, so try to eat them raw or as lightly cooked as possible.
The amazing health benefits of mushrooms range from fighting respiratory infections to cancer. The immune-enhancing actions of mushrooms are thought to help the body to more effectively attack microbial invaders. Mushroom’s phytochemicals, such as beta-glucan, enhance the activity of several different types of immune cells including natural killer cells, which attack and destroy virus-infected and cancerous cells.
Some of the best edible mushroom varieties you can eat to fortify your immune system include:
- lion’s mane
- chaga mushrooms – often consumed as a tea
While not everybody’s cup of tea, oysters are highly nutritious. They are rich in zinc, a mineral that plays a vital role in keeping the immune system strong. A 3.5-ounce serving of oysters also contains more than 100% percent of your recommended daily intake of vitamin B12 and significant amounts of copper, selenium, and vitamin D.
Eating raw oysters, however, can increase your risk for food poisoning and certain bacterial infections, so you should eat them with caution. Always buy oysters from a trusted source, and if you are going to eat them at home, consider cooking them to eliminate potentially harmful bacteria.
Like oranges and bell peppers, kiwis are packed with vitamin C and antioxidants that stimulate the immune system and fight free radical damage. One kiwifruit contains more than 200% of the recommended daily intake of vitamin C.
Turmeric comes from the root of Curcuma longa, a South Asian plant belonging to the ginger family. Curcumin, the main bioactive compound in turmeric, has been used for its medicinal, immune-boosting, and anti-inflammatory properties for thousands of years. Turmeric may play a role immune cell production, according to a 2007 study published in the Journal of Clinical Immunology.
But despite its impressive health effects, turmeric has one important downside: curcumin only makes up about 5 percent of turmeric, so the bloodstream can’t absorb it effectively when eaten by itself. The remedy: eat turmeric with black pepper.
Piperine – black pepper’s main bioactive compound – can increase curcumin’s bioavailability by up to 2000 percent. Mixing and matching these spices may also help boost turmeric effects, as studies suggest that piperine has significant anti-inflammatory, anti-cancer, and gastrointestinal properties. To fully benefit from its many protective and healing properties, consider taking a turmeric supplement with 1000-1500 mg a day of turmeric extract. Make sure it states it contains 95% curcuminoids on the label.
Nothing beats a warm, spicy ginger tea when you are feeling under the weather. Ginger boasts countless anti-inflammatory and antioxidant compounds that help combat inflammation and fight cellular damage. This aromatic root also has powerful antiviral and antibacterial properties, and laboratory studies suggest that it may have a protective effect against certain human respiratory viruses.
Treat yourself to a hot cup of ginger tea by peeling and thinly slicing a small knob of ginger root and boiling it in freshwater for at least five minutes (up to 10 minutes if you want an extra-spicy tea). Add an optional tablespoon of honey and a few drops of fresh lime juice to up its immune-boosting effects.
Spinach is high in vitamin C, vitamin A, and folate. Vitamin A is an umbrella term for a group of fat-soluble compounds essential for eye health, growth, cellular differentiation, and immunity. Specifically, vitamin A increases the activity of white blood cells such as lymphocytes. It also helps maintain the integrity of the thin sheet of cells that line and protect the internal and external surfaces of the body, called the epithelial tissues.
Whip yourself a supercharged immune-boosting breakfast smoothie for daily immune support by blending one cup of your favorite plant-based milk or yogurt, a couple generous handfuls of spinach, one tablespoon of freshly grated ginger, a teaspoon of turmeric (and a dash of black pepper to increase bioavailability), and a frozen banana.
Yogurt is a healthy delicious snack that you can indulge in any time of the day. Eating foods that contain live, beneficial microorganisms, like yogurt, promotes the growth and development of healthy bacteria in the gut.
Yogurt contains two very unique and special ingredients: probiotics and prebiotics. Probiotics are live organisms that are beneficial to your health when taken in adequate amounts. Prebiotics are non-digestible food ingredients that stimulate the growth of beneficial bacteria in your colon. Yogurt also gives you a healthy dose of calcium and is a significant source of protein, These foods are often called “probiotics” and can help with a wide range of health problems, including digestion issues, allergies, and inflammation. Probiotic foods have also been shown to boost the immune system and may even help you lose weight. Look for yogurts with the words “live cultures” printed on the label to ensure you are getting the probiotics your gastrointestinal tract needs for the best immune support.
12. Sunflower Seeds
Sunflower seeds are loaded with vitamin E, an essential micronutrient that plays a role in immune regulation. These tasty snacking seeds are also packed with zinc, selenium, B-1, manganese, phosphorus, magnesium, and B-6 which support your immune system as well as other bodily processes.
It’s an old folk remedy, but it works. Garlic contains bioactive compounds that help the immune system fight disease. It has also shown promise in preventing certain viral infections like the flu. A 2012 study published in the Journal of Clinical Nutrition reported that people who ate 2.5 grams of garlic extract daily experienced significantly shorter colds than a placebo group.
To maximize the health effects of garlic, crush it or slice it before you eat it and let it stand for 10 minutes to prevent the loss of its medicinal properties.
14. Sweet Potatoes
Orange-fleshed sweet potatoes are one of the best beta carotene sources, a plant-based compound that converts into vitamin A. They are also a good source of vitamin C and antioxidants. Leave the skin on your sweet potatoes to get the most health benefits out of them, and roast them on the oven or barbecue grill for a delicious, immune-boosting side dish.
A half-cup of almonds contains over 100% of the recommended daily amount of vitamin E – an essential vitamin for fighting pathogens. They also help you stay healthy by lowering LDL (“bad”) cholesterol and contain as much calcium as a ¼ cup of milk, helping your bones stay strong. The Dietary Guidelines for Americans recommend eating one ounce of almonds – about 23 nuts – per day, which looks roughly like the size of a lime or a 3” x 3” sticky note.
Incorporating these foods into your diet will yield big health benefits and should be part of your immune-boosting regimen.
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