Immune-Boosting Foods That Help Keep You Well

Broadly speaking, the immune system has two parts: innate and adaptive. Think of the innate immune system (located in the skin, salivary glands, and gastrointestinal and respiratory tracts) as a towering wall protecting a city. Its job is to prevent any invaders from gaining a foothold. The adaptive immune system functions like armed guards behind that wall, specifically targeting any intruders that get through. This system also remembers the approach that best defeats a specific intruder, so it can attack it more efficiently in the future.

As we age, the immune system might not produce as many immune cells, and those it does produce might not be as robust. But this isn’t inevitable, says Simin Meydani, PhD, professor emerita at the Friedman School of Nutrition Science and Policy at Tufts University in Boston. Her research shows that some older adults retain a younger person’s ability to fight infection. “There is a lot we can do to prevent the loss of immune function,” she says, “and one of the key factors is what we eat.”

Inflammation is the double-edged sword of immunity. When the immune system senses danger, it produces inflammatory cells that help the body fight infection and heal injured tissue. But if those cells stick around longer than they should, they can damage other cells in the body and lead to heart disease, cognitive decline, and other chronic conditions, as well as increase susceptibility to infectious diseases. “The inflammatory response is like a firehose,” Meydani says. “You want it to be strong to put out a fire, but you want it to turn off before it damages your whole house.”

“It’s estimated that about 70 percent of our body’s immune cells are located within the structures of the gut wall,” Calder says. “These immune cells communicate with each other and interact with the microbes living in the gut. They also move in and out of the gut wall, taking immune signals from the gut to other places in the body.”

To keep your gut in good working order, eat a variety of foods rich in healthy bacteria (yogurt, kefir, kimchi, miso) called probiotics. “Healthy bacteria produce compounds called short chain fatty acids,” Meydani says. “Some short chain fatty acids have an anti-inflammatory effect, which helps regulate your immune response and strengthen its impact.”

Also get plenty of fiber-rich foods— fruits, vegetables, and whole grains. They’re prebiotics, which help the good bacteria proliferate.

No single vitamin or mineral can keep you from getting sick, but certain ones can enhance your immune response.

• Vitamin C: This vitamin supports both the innate and adaptive immune responses. The daily value is 90 mg. But research suggests more may be better. A 2020 study in the journal Experimental Gerontology found that getting 500 mg of vitamin C daily for three months improved immune function in older adults to the point where it was comparable to that of younger adults. Good sources include citrus fruits, bell peppers, strawberries, and kiwifruit.

• Vitamin D: The daily value, 20 micrograms, can be difficult to get in food alone, and the ability to synthesize it from sun exposure diminishes with age. “You can get some from your diet, but many people, especially older adults, are deficient,” says Danica Cowan, MS, an integrative dietitian at the University of California San Francisco’s Osher Center for Integrative Medicine. Many studies link low levels to a higher risk of respiratory infections. A blood test can check your levels. If you’re low, ask your doctor if you should take a supplement in addition to seeking out more D in your diet. Good sources include fortified milk and orange juice, trout, salmon, and eggs.

• Vitamin E: The daily value is just 15 mg, but research suggests that getting up to 90 mg a day can improve age-related declines in immune function. Vitamin E is crucial for cell communication and the production of immune cell-building proteins. Good sources include flaxseeds, sunflower seeds, almonds, and peanut butter.

• Selenium: A deficiency of this mineral reduces the number of natural killer cells, while supplemental selenium has been shown to increase their activity. You need 55 micrograms per day. Good sources include tuna, halibut, shrimp, and brown rice.

• Zinc: This mineral is necessary for immune cell production and functioning. “Up to 20 or 30 percent of older adults have low levels of zinc,” Meydani says. “And in our research, we’ve seen that deficiency is linked to double the incidence of pneumonia in older adults.” The daily value is 11 mg. Good sources include oysters, fortified cereal, pumpkin seeds, and lentils.

Shelby Yaceczko, RD, an advanced practice dietitian at UCLA Health in Los Angeles, shares some breakfast, lunch, dinner, and snack suggestions that incorporate the latest advice and research on bolstering the immune system.

Breakfast
• Make a smoothie with plain Greek yogurt, flaxseeds, pomegranate seeds, and a little orange juice.

• Place sliced veggies (like bell peppers and onions) on a baking sheet. Create a space in the middle of them and crack an egg into it. Bake at 400° F until veggies are tender and the egg is cooked. Serve with a slice of whole-grain toast and a side of blueberries.

Lunches
• Top arugula with sliced pears and salmon. Add a drizzle of extra virgin olive oil and a squeeze of fresh lemon.

• Add fresh minced ginger to a simple lentil soup (homemade or low-sodium canned). Serve with a side salad of mixed greens, peppers, tomatoes, avocado, and pumpkin seeds, dressed with a red wine vinaigrette.

Dinners
• Mix cooked quinoa with chopped mushrooms and use it to fill hollowed-out bell peppers. Top with some tomato sauce and bake at 350° F until the peppers soften.

• Place shrimp on skewers and brush with miso glaze (homemade or store-bought). Grill the shrimp. (You can also use miso glaze on salmon and grill.) Serve over sautéed vegetables and brown rice.

Snacks
• Sliced apple with cinnamon and almond or peanut butter.

• Hummus on whole-grain toast with sliced tomato and cucumber.

• Berries and almonds.

• Roasted chickpeas spiced with herbs such as cumin or paprika.