NIFS Healthy Living Blog

Colder, drier air, less sunlight, more time spent indoors, increased holiday travel, and more mixing and mingling all contribute to rising rates of illness in the winter months. While no single food or supplement can prevent or treat illness, a balanced diet with the right combination of key nutrients can support a healthy immune system—making it easier for your body to fight off illness and infection.

A food-first approach is recommended when it comes to obtaining these nutrients. This means focusing on whole foods as your primary source rather than relying heavily on supplements. Below are several key nutrients for maintaining a healthy immune system this winter and the foods in which they can be found.

Vitamin C

Vitamin C is a well-established immune-supporting nutrient. It serves as an antioxidant, helping fight off cellular damage that can make cells more susceptible to illness and infection. It also supports the function of phagocytes, the cells that “eat” pathogens.

Most fruits and vegetables contain vitamin C, but seasonal quality can vary this time of year. It can be helpful to choose those that are in season, such as citrus fruits (oranges, clementines, grapefruits) and their juices, pomegranates, kiwis, bell peppers, and leafy greens like kale, Brussels sprouts, broccoli, and cabbage. Frozen fruits are also a great option, as they are typically picked at peak ripeness and remain just as nutritious as fresh varieties.

Vitamin D

Vitamin D helps activate white blood cells that detect and destroy pathogens. Without adequate vitamin D, these cells are not as effective. Sunlight exposure contributes significantly to vitamin D production, but during the winter months, sunlight and time spent outdoors decrease—leading to lower natural production. Vitamin D is also found naturally in very few foods, so unless you’re intentional about including these foods regularly, you may fall short.

Vitamin D is primarily found in fortified dairy products and dairy alternatives (almond, soy, coconut), fatty fish (salmon, mackerel, sardines, anchovies), egg yolks, and mushrooms exposed to sunlight. If you don’t consume several servings of these foods on a regular basis, your physician can order a blood test to determine whether your levels are adequate and if a supplement is indicated.

Zinc

Zinc plays an important role in the normal development and function of immune cells. It may also help inhibit the replication of certain viruses and bacteria, potentially shortening the length of infection. Zinc is best absorbed through animal sources such as beef, pork, turkey, seafood (oysters, crab, shrimp, sardines), eggs, and dairy products. It can also be found in plant sources, including seeds (pumpkin, hemp, chia), nuts (cashews, almonds, peanuts), beans, lentils, and whole grains.

No one supplement or food can prevent or treat illness, and diet is only one part of the equation. To further reduce your chances of getting sick this winter, remember to wash your hands regularly, sanitize frequently touched surfaces, cover your coughs, and stay well hydrated and well rested.

By focusing on nutrient-dense foods and simple daily habits, you’ll give your immune system the support it needs all season long.

As the weather turns colder and we spend more time indoors, viruses will become more active among the population. Healthy eating can help you boost your immunity. Here are five of the top choices for fighting colds and flu with food.

Citrus Fruits

Oranges, clementines, lemons, and grapefruits are all excellent sources of vitamin C, an antioxidant that helps protect immune cells from oxidative stress during the early stages of an immune response. Research has shown that a deficiency of vitamin C can result in impaired immunity and a greater susceptibility to infection.

Fatty Fish

Fatty fish, such as sockeye salmon and rainbow trout, are often great sources of Vitamin D, a nutrient that plays a role in innate and adaptive immune responses. One study found that vitamin D supplementation resulted in a 42% decrease in the incidence of influenza infection, while another study revealed individuals with lower serum vitamin D levels were more likely to self-report recent upper respiratory tract infections when compared to individuals with sufficient vitamin D levels.

Nuts, Seeds, and Plant-based Oils

Nuts, seeds, and plant-based oils are high in vitamin E, an antioxidant that has been shown to enhance immune response and confer protection against several infectious diseases. These foods are also high in omega-3 fatty acids, which may help strengthen your immune cells, although more research is still needed to fully support these claims.

Sweet Potatoes

Sweet potatoes and other red or orange fruits and vegetables are typically high in vitamin A, which plays a crucial role in the maintenance of the human immune system. Vitamin A supplementation has been shown to have a therapeutic effect on diseases transmitted through the respiratory tract, such as pneumonia. For reference, one sweet potato contains 156% of your daily vitamin A requirements.

Oysters

Three ounces of raw oysters provides 291% of your daily zinc needs. Zinc helps the immune system function properly and also has wound-healing properties. Studies have shown that a zinc deficiency is associated with severe immune dysfunction.

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Eating the preceding types of foods can help you strengthen your immune system against the annual winter onslaught of colds and flu. If you’d like more help planning a healthy diet, schedule a NIFS nutrition coaching session.

This blog was written by Lindsey Recker, MS, RD, NIFS Registered Dietitian. To learn more about the NIFS bloggers, click here.

If you are like most people, the dreaded winter flu season can be scary. However, certain foods can help you fight off the flu or lower your chances of catching that nasty bug.

Immunity-Boosting Foods

Here are some foods (and drinks) to fill up on to help fight the flu:

• Green tea: Green tea is packed with antioxidants; sip it hot or cold throughout the day to help keep the flu away.
• Sweet potatoes: This bright orange food is packed with Vitamin A to help keep those free radicals at bay that can threaten to weaken your immune system. Pop a sweet potato in the microwave for 7 minutes for a quick and easy addition to lunch or dinner.
• Yogurt: Yogurt naturally contains probiotics that help keep your immune system healthy and strong. It's such an easy and filling snack to grab or use as a substitute for sour cream, mayonnaise, or cream in high-fat recipes.
• Tuna: Tuna is an excellent source of selenium and Vitamin D, which helps protect cells from free radicals and improve your immune system. Try mixing a pouch of tuna with some plain Greek yogurt and serve it atop a bed of leafy greens.
• Mushrooms: Mushrooms are rich in selenium, low body levels of which have been found to increase your chance of getting the flu. Chop them up and add them to a pasta dish, salad, or soup.
• Peanuts: This tasty snack is full of zinc, which helps keep your immune system working properly. A handful is the perfect amount to grab for an afternoon snack or to throw in a stir-fry at dinner.
• Water: This essential nutrient keeps the body running efficiently. Getting fluids in various forms is vital. Tea, 100% juice, coffee (preferably decaffeinated), and water-filled foods such as fruits and vegetables all count toward your hydration needs.

A Yummy Flu-Fighting Recipe

Try this recipe that incorporates a couple of these flu-fighting foods:

Sweet Potato Tuna Melt

1 large sweet potato (halved)
¾ cup canned tuna
½ cup plain Greek yogurt
½ tsp garlic seasoning
½ tsp onion seasoning
Lemon pepper to taste
½ cup shredded part-skim mozzarella cheese

1. Preheat oven to 400 degrees. Place potatoes, cut side down, on a baking sheet and roast until tender, about 30 minutes.
2. Remove potatoes and allow to cool. Meanwhile, combine tuna, Greek yogurt, and spices in a bowl.
3. Top potatoes with tuna and sprinkle with cheese. Place under the broiler for 1 minute or until the cheese has melted.

Enjoy with a glass of green tea!

Nutritional Balance Is the Key

As with most things, a balanced diet is the key. A diet high in a variety of produce, lean meats, whole grains, and low-fat dairy, along with moderate exercise, adequate sleep, and minimal stress, contributes the most to a well-functioning immune system and faster healing if the flu does strike. Incorporate these foods, but also continue to work on overall balance to your life.

This blog was written by Angie Mitchell, RD, Wellness Coordinator. To find out more about the NIFS bloggers, click here.