Foods that boost your immune system: 4 nutritionists share what they eat during the cold season - CNBC

As we head into another flu season amid the continued threat of Covid variants, the question that's top of mind for everyone is: "What can I do to boost my immune system?"

One of the best places to start is with your diet. Research shows that our gut microbiome — or the trillions of microorganisms that live in the intestinal tract — is directly linked to immune health. 

Here are four healthy, nutritionist-approved recipes to strengthen your immune system this winter:

1. Haitian soup joumou

Colorful and nutritious soup joumou is also known as Haitian New Year's Soup.

Photo: Wini Lao Photography

There's truth behind the saying: "Eat the rainbow." Recent studies have found that phytonutrients, which are minimally processed — and often colorful — plant foods, can support proper immune balance and function. 

Maya Feller, a dietitian and author of the forthcoming book "Eating From Our Roots," is a fan of soup joumou. Native to Haitian cuisine, this dish is often made with squash, beef and assorted vegetables.

"Not only is it representative of my culture and heritage, it's also rich in phytonutrients and fiber," says Feller, whose approach to nutrition is to make food more inclusive and reflective of the diverse world we live in.

Ingredients

For the soup:

• 1 pound boneless beef chuck, cut into 1-inch cubes
• 1/2 cup Epis seasoning
• 3/4 cup lime juice
• 3/4 cup olive oil
• 1 onion, diced
• 3 garlic cloves, minced
• 3 celery ribs, diced
• 2 scallions, diced
• 1 bunch parsley, chopped
• 1 shallot, chopped
• 2 tomatoes, roughly chopped
• 8 cups low-sodium chicken broth
• 1 winter squash, peeled and cut into 3-inch cubes
• 5 medium potato, roughly chopped
• 5 carrots, roughly chopped
• 1 habanero pepper

For the dumplings:

• 1 1/2 cups Einkorn flour
• 1/4 teaspoon baking powder
• 1 teaspoon extra virgin olive oil
• Pinch of flakey salt
• 1/8 teaspoon fresh black pepper
• Ripe avocado, for garnish

Steps

1. Marinate the beef in seasoning and lime juice overnight.
2. Combine onions, garlic, celery, scallion, parsley and shallots into a large pot. Sauté with olive oil for five to seven minutes over medium heat, or until the vegetables are soft.
3. Add the tomatoes, broth, squash, potato, carrots, habanero and marinated meat into the pot. Cover and cook for 60 to 90 minutes over medium-low heat.
4. Meanwhile, combine the dumpling ingredients into a medium-sized bowl and mix. Add two tablespoons of water at a time, as needed.
5. Take a golf ball-sized portion of dough and roll it between your hands until it becomes elongated.
6. Drop the dough balls into the soup one by one. Cook for another 15 to 20 minutes.
7. To serve, spoon a heaping portion into a bowl and top with some avocado.

2. Vietnamese slow-cooked pho 

Chef Tessa Nguyen's pho recipe contains fresh herbs, crunchy vegetables and high quality beef protein, all of which are great for boosting immunity.

Photo: Tessa Nguyen

Nutritionist and chef Tessa Nguyen's dishes are inspired by ingredients that "have been fixtures around the table in many cultures and for many centuries," such as star anise, cloves, Sichuan pepper and ginger.

Her go-to dish for immune support is a batch of slow-cooked pho. "It's full of nourishing ingredients that fulfill the body's needs any time of year, but especially during the colder months."

Nguyen's recipe is filled with ingredients that are beneficial for immune health, like fresh herbs, vegetables and meat protein.

Ingredients

For the broth:

• 2 pounds of beef 
• 1 1/2 teaspoons five spice powder
• 1 tablespoon fish sauce (substitute with soy sauce if you have a fish allergy)
• 1/2 teaspoon salt
• 1 bunch of green onions, chopped
• Enough water to fill up your slow cooker after adding ingredients above

For the noodles and toppings:

• 1 cup rice noodles
• Shredded beef from pho broth
• Toppings: chopped cilantro, Thai basil leaves, chopped green onions, thinly sliced white onions, bean sprouts, sliced jalapeños, lime wedges, sriracha, hoisin sauce

Steps

1. In a slow cooker, combine all broth ingredients and set to low heat. Nguyen recommends cooking for 24 hours, but says it still tastes great even after just eight hours.
2. Add cooked rice noodles into a bowl and pour the broth over it.
3. Add toppings.

3. Fragrant cauliflower, turmeric and ginger soup

Anti-inflammatory foods like ginger, turmeric and chickpeas are great immune boosters.

Photo: Hazel Wallace

Hazel Wallace, a nutritionist and founder of The Food Medic, recommends getting a balance of nutrients from anti-inflammatory foods like chickpeas and lentils, nuts and seeds, olive oil, fish and herbs and spices.

Her cauliflower soup recipe contains turmeric and ginger, both of which have anti-inflammatory properties. "It's also incredibly warming and nourishing for the fall, or whenever you're feeling under the weather," she says.

Ingredients

• 2 tablespoons extra-virgin olive oil
• 1 large (or 2 small heads of cauliflower), cut into florets
• 1 white onion, diced
• 1 heaped teaspoon fresh ginger, grated or diced
• 2 teaspoons ground turmeric
• 3 garlic cloves
• 900 milliliters vegetable stock
• 2 tablespoons soy sauce
• 1/2 teaspoon salt
• 1 thick slice of one day-old bread
• 3 teaspoons coconut cream (or yogurt), to garnish
• Chili flakes, for garnish
• Fresh coriander, for garnish

Steps

1. Preheat oven to 356 degrees Fahrenheit. Scatter the cauliflower florets on a large tray. Drizzle with one tablespoon of oil and roast in the oven for 30 minutes until golden.
2. Meanwhile, in a large pan, heat 1/2 tablespoon of olive oil and add the white onions. Cook for five minutes until they are translucent.
3. Transfer the onions into a blender, along with the turmeric, ginger, garlic, vegetable stock, soy sauce and a pinch of salt. Add the roasted cauliflower and blend until smooth.
4. Heat the soup on low heat for about 10 minutes.
5. Meanwhile, tear the bread into large chunks.
6. Combine the remaining 1/2 tablespoon olive oil with a tablespoon of soy sauce into a large bowl. Add the bread chunks. Place them onto a tray and cook in the oven for eight minutes to toast.
7. Serve the soup with a drizzle of coconut cream and top with the chunky croutons, fresh coriander and chili flakes.

4. A bright and vibrant defense smoothie

Simone Wilson's defense smoothie recipe includes bee pollen which is rich in B vitamins, amino acids and antioxidants. 

Photo: Simone Wilson

We all need a break from hot dishes, even during the colder months.

Nutritionist Simone Wilson's go-to is a refreshing smoothie blend of banana, mango, hemp seeds, bee pollen, kale, orange juice, yogurt and kale. 

"This simple recipe is high in antioxidants, including vitamins C and A, to help fight free radical damage and support the immune system," she says.

Ingredients

• Half a ripe banana, fresh or frozen
• 1/2 cup mango chunks, fresh or frozen
• 1 cup orange juice
• 1/2 cup unsweetened Greek (or cashew yogurt)
• 3 tablespoons hemp seeds
• 1 teaspoon bee pollen
• 1 handful spinach (or kale)
• 4 ice cubes (leave this out if you are using all frozen fruit)

Steps

1. Throw all ingredients into a blender and blend on high speed until smooth. Add more liquid if the texture is too thick, or more ice if it's too thin. 
2. Serve immediately.

Alexandra Hayes Robinson a lifestyle writer and editorial director at The Female Quotient. Formerly, she was a content director at Thrive Global.

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Foods that boost your immune system: 4 nutritionists share what they eat during the cold season - CNBC
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