Boost your immune system with these foods

As the world reacts and reels in response to the COVID-19 pandemic—with no known treatments or vaccines yet available—it may be comforting to know that there are some foods you can turn to that can boost your immune function. As physicians, you are aware of the value of proper nutrition in bolstering cellular health and, therefore, immune health.

Here are a few of the foods that you can turn to in these infectious times to give your immune system a fighting chance.

Poultry. Chicken soup is perhaps the quintessential “sick” food. Its origins stretch as far back as 7,000 to 10,000 years ago, and is associated with the domestication of fowl, probably in either ancient India or Southeast Asia.

The combination of beneficial ingredients in chicken soup make it the ultimate immune booster. For example, researchers have shown that chicken soup can significantly inhibit neutrophil migration to sites of infection or inflammation in those with symptomatic upper respiratory tract infections. Cysteine, in particular, is an ingredient of chicken that has been shown to stop the movement of white blood cells and decrease the mucus associated with colds.

No list of immune-boosting foods would be complete without a shout-out to poultry, namely chicken or turkey. All poultry is high in vitamin B6, and just 3 oz contains up to 50% of the daily recommended amount. Vitamin B6 is important in the formation of new and healthy red blood cells. Chicken soup also contains vitamins A and C, magnesium, phosphorus, and antioxidants, which are all important for immune function. The protein in chicken and turkey also provides you with amino acids, which are used by your body to build antibodies to fight infection. Also, boiling poultry—to make soup—releases gelatin, chondroitin, and other nutrients that help your gut and immune system as well. Chondroitin, for example, is an important component of mucin that affects gut permeability and intestinal immune mediation.

Although canned chicken soup is fine, try to make chicken soup from scratch for the most immune benefits. You’ll know that your ingredients have not been processed, and can easily control the amount of salt you use. Fresh is always better!

Almonds. Almonds are an excellent source of vitamin E, which—along with vitamin C—is a key player in keeping your immune system healthy. It, too, is a potent antioxidant, which is important to proper immune function. If your T-cells are damaged via significant oxidative stress, they can’t mount a sufficient immune response against whatever pathogen is attacking the body. Vitamin E also plays an important role in T-cell differentiation. 

Just half-cup of almonds will give you almost 100% of the recommended daily amount of vitamin E. A handful of almonds is a great snack anytime, or you can include them in your cooking, for added texture and flavor.

Mushrooms. Mushrooms are high in selenium and B vitamins, including riboflavin and niacin. All are great for your immune system. Selenium, for example, is an antioxidant that helps lessen oxidative stress, reducing inflammation and enhancing immunity. And vitamin B6 has been shown to support important biochemical reactions in the immune system.

Another plus? Mushrooms are high in polysaccharides, which are sugar-like molecules that boost immune function. The polysaccharides found in mushrooms interact with macrophages, neutrophils, monocytes, and dendritic cells—all big immune system team players. Polysaccharides work to enhance and/or activate the immune responses of these cells and increase the production of reactive oxygen species and enhance cytokine and chemokine secretion.

Shiitake mushrooms, in particular, are a great choice because they are high in the B vitamins, vitamin D, selenium, niacin, and seven of eight essential amino acids. Chaga mushrooms are also an excellent immune-boosting choice. They have the highest concentrations of antioxidants and also contain a high amount of zinc, which is also important for immune function.

Mushrooms are a savory, delicious addition to any meal. You can sauté them with onions, for example, for a welcome side dish to any meal. Or include them in a salad, or just eat straight, with a little dip.

Garlic. Garlic is an important ingredient in nearly every cuisine in the world—and for good reason. Garlic contains the sulfoxide alliin, and when crushed or chewed, alliin turns into allicin. Because allicin is unstable, it converts to sulphur-containing compounds, which are thought to give garlic its medicinal properties. Garlic has been shown to enhance the function of the immune system by stimulating macrophages, lymphocytes, natural killer cells, dendritic cells, and eosinophils. It does so by modulating cytokine secretion, immunoglobulin production, phagocytosis, and macrophage activation.

Garlic is simple to include in most any meal you are preparing. Use it when making roasts, chicken, lamb, and fish. Or even add it to rice or mashed potatoes while boiling for a delicious, flavorful, and healthy kick to your meals.

Citrus fruits. Citrus fruits contain vitamin C, an essential micronutrient. It contributes to the improved health of your immune system by supporting cellular functions in both the innate and adaptive immune system. For example, vitamin C supports epithelial barrier function against pathogens. It may also enhance differentiation and proliferation of the mega-important immune system superstars: B- and T-cells.

Vitamin C may also increase the production of white blood cells—lymphocytes and phagocytes—that protect the body against infection. In addition, vitamin C supplements may prevent and treat respiratory and systemic infections. Vitamin C also acts as an antioxidant, helping to fight free radicals that damage the immune system and keep it from functioning properly.

Vitamin C, however, isn’t the only power player found in citrus fruits. Flavonoids—plant compounds that have anti-inflammatory, antioxidant, and free-radical scavenging properties—are another ingredient of citrus fruits that give the immune system a boost by helping to reduce inflammation and speed recovery from illness.

Because your body can neither produce nor store vitamin C, it’s important to consume rich sources of vitamin C daily—especially when you are ill and your levels may be depleted. Citrus fruits, for example, are excellent sources, and include oranges, tangerines, lemons, limes, grapefruits, and clementines. Some other ways of adding some natural vitamin C to your diet include topping a salad with a squeeze of lemon or lime or adding a squeeze of any citrus fruit to a cup of plain water or even tea. All are easy ways to get your daily vitamin C fix.

But, if you’re not a fan of citrus fruits—or if you take certain medications that may adversely interact with citrus fruits or citrus juice—consider taking vitamin C supplements, which are plentiful and easy to find.

Pomegranates. The power of pomegranates in immune health is multifactorial and includes many “genres” of pathogens. Consider that compounds found in pomegranate extract have been shown to inhibit the growth of harmful bacteria such as Escherichia coli O157:H7, Salmonella, Yersinia, Shigella, Listeria, Clostridium, and Staphylococcus aureus. Pomegranate extracts have also been shown to have antiviral properties that are effective against the flu and other viruses. As if this weren’t enough, pomegranate extracts have also been shown to promote the growth of beneficial gut flora—such as Bifidobacterium and Lactobacillus—that can also give a powerful boost to your immune system.

Get your pomegranate fix by drinking it in delicious juice form. You can also eat pomegranates whole, or sprinkle its seeds on salads or yogurt for a delicious change of pace.