Want to Boost Your Immune System? Drink Citrus Fruit Juice

It's commonly thought that drinking a tall glass of orange juice, or other citrus juice, can help support the immune system—considering that it's chock-full of immune-supporting nutrients like vitamin C and folate. Now, science is backing that up.

According to new research, natural chemicals found in a glass of citrus juice—for example orange or grapefruit—may support immunity and reduce inflammation. For this review, researchers in Europe evaluated over 200 studies.

The results showed that the micronutrients and other bioactive compounds found in citrus fruit juices play a role in controlling oxidative stress and inflammation and in supporting the immune response. The July review was published in the journal Frontiers in Immunology.

"This review article reinforces what we know about the vitamin C and hesperidin found in 100% orange juice," Rosa Walsh PhD, director of scientific research at the Florida Department of Citrus, tells Verywell. "While vitamin C’s association with a healthy immune system tends to be well known, we are happy to see more education about the importance of hesperidin and how everything works together. Hesperidin, which is found almost exclusively in orange juice and oranges, in combination with vitamin C, can help support antioxidant activities in the body which in turn may help lessen oxidative stress and inflammation." 

How Does Citrus Support Immune Health?

In order to stay healthy, a functioning immune system is key. While some factors of our immune health are out of our control, there are some steps we can take to support it, like drinking citrus fruit juice.

Vitamin C deficiency can impair immunity and make a person more susceptible to infections. However, vitamin C is not the only shining star nutrient in 100% orange juice—the beverage also contains folate, which plays a role in the function of many types of immune cells.

In addition to micronutrients, 100% citrus fruit juices contain polyphenolic flavonoid compounds— natural compounds that are believed to support the immune system.

The main polyphenol in orange juice is hesperidin but others, such as narirutin and naringin, are noteworthy as well. Research shows that all three compounds are anti-inflammatory. Since uncontrolled inflammation can cause damage to tissues and lead to illness, including anti-inflammatory components in your diet may offer some benefit.

Melissa Azzaro, RD, a registered dietitian and the author of "A Balanced Approach to PCOS," tells Verywell that the results of the new study reiterate why including certain foods in our diets is important for supporting our immune health. 

While many people take vitamin C supplements to support their immune system, there are certain components in food that just cannot be reproduced in a pill.

“For example, when you drink a glass of orange juice, you are not only getting vitamin C, but you are also getting folate, polyphenols, and other components that play a role in immune health," Azzaro says. "Plus, the hydration that orange juice provides can help support our immune health too. For this reason and others, I tend to recommend leaning on getting nutrients from food sources instead of pills when possible.”

Can Drinking Orange Juice Protect Against COVID?

Throughout the COVID-19 pandemic, many people have prioritized keeping their immune systems strong. While it isn't a guarantee you won't get the virus, having a strong immune system will help if you do get sick.

The researchers of this recent review reported that some preliminary data suggested that drinking orange juice could potentially offer some protection against COVID-19. However, strong clinical trials in humans would be needed to really determine whether that's true.

The results of some modeling studies suggested that hesperidin—an antioxidant found in citrus—could interfere with the virus’s entry into host cells, possibly making infection difficult to achieve.

Similarly, laboratory studies have found that hesperidin and naringenin—two key compounds found in orange juice—can impede replication of the virus.

While none of these results are conclusive, this early research suggests that at the very least, there is no harm in including the drink in your diet if you're trying to bolster your immune system to fight any infection.

Other Ways to Support Your Immune System

In addition to including vitamin C-rich foods in your diet, there are some other simple ways that you can aid your immune system in fighting off a cold, the flu, or other infections:

• Get 7 to 8 hours of quality sleep every night
• Limit or avoid alcohol
• Participate in regular physical activity
• Make sure that you have adequate levels of other important nutrients (lik D), and supplement if needed
• Add prebiotic-rich fruits and vegetables (like a slightly underripe banana, avocado, and Jerusalem artichoke to support a healthy gut microbiota) to your diet
• Manage stress