9 easy food swaps dietitians recommend making to support a strong immune system

Despite what some influencers may tell you, there’s no magic supplement or food that will keep coughs, sore throats and sniffles away. Even those beloved vitamin C powders won’t give you extra protection if you’re already getting enough vitamin C each day (which is easier than you might think). When it comes to dodging the cold that’s making the rounds at the office or your kid’s school, there’s no shortcut. Washing your hands and getting enough sleep are still among your best defenses. But what you eat plays a role too.

As a registered dietitian, I get asked all the time what the “best” food is for avoiding illness. Some foods do pack more immune-supporting nutrients than others, but my answer usually isn’t very satisfying: There is no one “best” food. What really moves the needle is your overall diet, including what you drink.

Want to keep your immune defenses strong? Instead of just rattling off foods that are high in vitamin C or zinc, I talked with two fellow dietitians to put together nine easy swaps you can make throughout the day to support your immune system.

✅ Incorporate bell peppers and kiwi daily instead of relying on Emergen-C or other vitamin C supplements.

Vitamin C is popular for a reason. It’s an antioxidant that helps protect immune cells, and it supports the growth and activity of white blood cells that fight off infections. It also plays a key role in wound healing and skin health, helping keep pathogens from entering your body.

A 2025 review suggests that taking vitamin C regularly may slightly shorten the length of a cold, though it doesn’t reliably prevent one. A true vitamin C deficiency, on the other hand, can raise your risk of infection and make it harder to recover from illness or injury.

Registered dietitian and sports nutrition consultant Amy Goodson recommends snacking on bell peppers because a single pepper can provide a day’s worth of vitamin C. I’m also a fan of kiwis: One medium kiwi provides about 71% of the daily value (DV). Vitamin C-rich foods come with other immune-supporting nutrients too, such as beta-carotene (which your body converts to vitamin A) in red peppers.

✅ Snack on almonds or sunflower seeds instead of chips.

Craving something salty and crunchy mid-afternoon? Reach for seasoned almonds or sunflower seeds instead of potato chips. Both are packed with vitamin E, an antioxidant that helps immune cells do their job, and they also provide some zinc, which supports the growth and function of immune cells.

Swapping out chips may help your gut too. Diets high in ultra-processed foods can contribute to low-grade inflammation and may negatively affect gut health, which, as we’ll discuss later, plays a large role in immune health. While research is ongoing, a 2021 review in Nutrition suggests that diets high in ultra-processed foods could weaken immune function.

✅ Consider adding a vitamin D supplement to your morning routine instead of relying on sun exposure.

Vitamin D is best known for bone health, but it also plays a role in immune health. Rather than ramping up your defenses, it helps regulate the immune system and keep it balanced. Supplements haven’t been proven to prevent illness, but being deficient has been linked with a higher risk of getting sick and risk of hospitalization for a respiratory infection. According to NHANES data, 22% of Americans had moderate vitamin D deficiency, and about 41% had insufficient vitamin D levels under the study’s criteria.

“Supplements haven’t been proven to prevent illness, but being deficient has been linked with a higher risk of getting sick, and very low vitamin D levels have been linked with a higher risk of hospitalization for a respiratory infection.”

Talk to your doctor or registered dietitian before starting any supplement. That said, a vitamin D supplement is one that many people can benefit from because, unlike vitamin C, it’s hard to get enough vitamin D from food alone. Fatty fish and fortified dairy help, but the body makes most of its vitamin D from sunlight. That’s not always reliable, since it varies with season, location and skin tone, and going without sunscreen raises your risk of skin cancer.

✅ Choose sweet potatoes, winter squash or carrots as your side instead of white rice or French fries.

Vitamin A supports your body’s natural defenses through its role in the production and function of white blood cells and in maintaining the mucous membranes that act as barriers against germs.

Orange vegetables like sweet potatoes, butternut squash and carrots are excellent sources of beta-carotene, which your body converts to vitamin A, making them a nutrient-rich swap for starchy sides like white rice or French fries. Making your own sweet potato or carrot fries at home is an easy way to get the crispy fix with far less oil than deep-fried versions. The air fryer is perfect for this, and a light drizzle of olive oil helps your body absorb the beta-carotene.

✅ Blend kefir into your morning smoothie instead of, or in addition to, regular milk.

Christina O’Connor, a registered dietitian at Pendulum Therapeutics, says prioritizing gut health is one of the best ways to support your immune system. An estimated 70% of immune cells are in and around the gut, and beneficial bacteria work hand in hand with them. “The microbes living there help train the immune system to differentiate between helpful and harmful,” O’Connor explains. “They also produce compounds, like short-chain fatty acids from fiber, that support the barrier and help keep inflammation in check.”

While probiotic supplements can help some people, O’Connor recommends starting with whole foods, especially fermented ones like kefir, as part of your daily routine. If you’re new to kefir, think of it as tangy, drinkable yogurt. You can enjoy it on its own in a glass, but I like to buy unsweetened kefir and use it as the base for my smoothies.

✅ Add flavor and crunch to your sandwiches with sauerkraut on top of (or instead of) lettuce and tomato.

Not a fan of kefir, or looking for more ways to work probiotics into your day? O’Connor also suggests sauerkraut, which is fermented cabbage. Look for refrigerated, unpasteurized versions, since the shelf-stable kind doesn’t contain live cultures. Sauerkraut also provides some vitamin C and iron.

Pile it on your next sandwich for extra crunch and tang, and keep portions in check if you’re watching your sodium intake. Or make your own by shredding cabbage, massaging it with salt and letting it ferment in a jar for a week or two.

✅ Sip a mocktail of seltzer, tart cherry juice and mint instead of a cocktail.

Drinking less alcohol may benefit your health in several ways, including your immune system. Instead of shaking up a cocktail at night, try a mocktail (just keep an eye on the added sugar).

One of my go-tos is seltzer with a splash of 100% tart cherry juice and fresh mint. It’s refreshing, alcohol-free and hydrating, which matters for immune health because water helps circulate immune cells through your blood and lymph, supports protective mucous membranes and aids digestion. The tart cherry juice also provides antioxidants called anthocyanins and a small amount of vitamin C.

✅ Make a Greek yogurt parfait or cottage cheese bowl instead of cereal for breakfast.

I’m not here to hate on breakfast cereal (some options are quite healthy), but especially during cold and flu season, it’s smart to spread your protein out across the day, since your body needs it to build immune cells and antibodies. A Greek yogurt parfait is a great swap that’s just as quick as a bowl of cereal. Add plain or low-sugar Greek yogurt to a bowl, then top with fruit and low-sugar granola. Look for one made with almonds and seeds for a dose of vitamin E. Check the label for “live and active cultures” to get the probiotic bonus.

Cottage cheese is another good option. It’s protein-packed and milder in flavor than Greek yogurt, and it pairs well with berries or sliced peaches.

✅ Eat shellfish one night a week instead of another chicken dish.

Zinc is essential for the growth and function of immune cells that help detect and destroy pathogens. It also helps activate T-cells, which attack infected cells, and supports the skin and mucous membranes that keep germs out. One of the best food sources? Shellfish.

Oysters have more zinc than any other food, but crab and lobster are also excellent sources. Depending on the variety, a serving of crab or lobster can contain several times more zinc than the same amount of chicken breast. Shrimp has less than lobster or crab, but it’s a quick, budget-friendly option.

If you have a shellfish allergy or can’t buy it regularly, Goodson says beef is another excellent option. Beef is high in zinc, she notes, and it’s also a high-quality protein source and rich in iron, another nutrient that plays a role in immune function.

Meet our experts

• Amy Goodson, MS, RD, CSSD, LD, author of The Sports Nutrition Playbook

Our health content is for informational purposes only and is not intended as professional medical advice. Consult a medical professional on questions about your health.