Study: Eating leafy greens helps boost your immune system (recipes included)
03/24/2022 / By Rose Lidell / Comments
Study: Eating leafy greens helps boost your immune system (recipes included)

According to a study, eating cruciferous vegetables like broccoli, cauliflower and kale can help boost the immune system’s ability to fight intestinal pathogens.

The researchers who conducted the study hope that their findings can be used to help people with inflammatory bowel diseases.

AhR and external pollutants

The protein aryl hydrocarbon receptor (AhR) helps protect humans from external pollutants, toxins and pathogens at barrier sites in the body like the skin, lungs and gut.

While studying the role of AhR in the gut, researchers at the Francis Crick Institute discovered that Cyp1a1, another protein, regulates immunity in the gut by providing feedback on AhR signaling. Cyp1a1 degrades AhR ligands, the molecules that activate AhR.

But too much Cyp1a1 can deplete AhR ligands altogether and make you more susceptible to bacteria like pathogenic E. coli. It might also be involved in the development of inflammatory bowel disease (IBD).

Dr. Brigitta Stockinger, who led the study, explained that AhR deficiency is linked to various problems for the intestinal barrier. This is because the immune cells that protect humans from trillions of intestinal bacteria and incoming intestinal pathogens require signals through AhR for their survival.

Molecules that activate AhR can come from your diet and your intestinal bacteria. The activation of AhR then turns on enzymes like Cyp1a1. Normally, these enzymes degrade the molecules that originally activated AhR and turn it back off.

For the study, the researchers used mice with overactive Cyp1a1. This depleted AhR ligands and resulted in fewer immune cells that depend on AhR ligands.

Compared to normal healthy mice, those with overactive Cyp1a1 were unable to fight off an infection with Citrobacter bacteria, the mouse version of human pathogenic E. coli bacteria.

Nutrients in cruciferous vegetables inhibit Cyp1a1

The researchers also found that adding some nutrients found in cruciferous vegetables to the mice’s diet helped control the increased activity of Cyp1a1 and provided extra AhR-activating molecules.

“Previous work has mostly focused on the consequences of complete absence of AhR itself in various cell types, but this is not a scenario that will apply to humans as AhR deficiency would not be compatible with life,” commented Stockinger.

But according to the study findings, it is possible that certain individuals have mutant Cyp1a1 enzymes with abnormally high activity. This may have a role in inflammatory intestinal diseases where those with genetically determined overactive Cyp1a1 would be particularly sensitive to infections.

These people could potentially improve their intestinal immune function by eating cruciferous vegetables like broccoli, kale and cauliflower, which are high in Cyp1a1 inhibitors and molecules that activate AhR.

Tasty recipes with nutritious cruciferous vegetables

As the study has proven, following a balanced diet and eating cruciferous vegetables can help boost your immunity and protect you from intestinal pathogens.

Below are some recipes made with nutrient-rich veggies.

Roasted broccoli, cauliflower and kale salad

This vegetarian recipe for salad combines three amazing superfoods: broccoli, cauliflower and kale.

Ingredients for 8 servings:

  • 2 cups cooked wild rice
  • 1/4 cup dried cranberries
  • 1/4 cup pepitas
  • 1/4 cup raisins
  • 1/4 cup toasted pine nuts, or sunflower seeds for a nut-free version
  • 1 small broccoli, cut into florets
  • 1 small cauliflower, cut into florets
  • 5 ounces baby kale
  • 1 (15-ounce) can chickpeas, drained, rinsed and patted dry
  • 2 tablespoons chopped fresh mint
  • 2 tablespoons chopped fresh parsley
  • 2 tablespoons hemp hearts
  • Olive oil
  • 1/2 lemon, juiced
  • 1 pinch black pepper, freshly ground
  • 1 pinch kosher salt
  • Za’atar (spice blend made with dried thyme, ground sumac, toasted sesame seeds and flaked sea salt)


  1. Preheat the oven to 425 F.
  2. Place the broccoli, cauliflower and chickpeas onto a rimmed metal baking sheet. Drizzle with olive oil, then season with the za’atar. Roast the mixture for 20 minutes on the middle rack of your oven, rotating the pan 1/2 through.
  3. Get a large mixing bowl and combine the cooked wild rice with the roasted vegetables, along with the chickpeas, pine nuts, pepitas, raisins, cranberries, hemp hearts, mint and parsley.
  4. Add the baby kale, fresh lemon juice and two tablespoons of olive oil. Season with salt and pepper to taste.
  5. Toss the mixture to combine and coat the salad. Serve immediately.

Veggies and cheese

This recipe puts a healthy spin on mac and cheese by replacing the macaroni with broccoli, cauliflower and kale.

Ingredients for 4 servings:

  • 1 small head fresh broccoli, rinsed, cut into 2-inch florets (Makes about 3 cups,)
  • 1 small head fresh cauliflower, rinsed, cut into 2-inch florets (Makes about 3 to 4 cups.)
  • Fresh baby kale, about 2 cups or more
  • 2 cups shredded mild cheddar cheese
  • 1/2 cup heavy cream
  • 2 tablespoons grated Parmigiano-Reggiano cheese
  • 1/4 teaspoon salt
  • Fresh cracked pepper to taste, optional


  1. Preheat oven to 350 F.
  2. Steam the broccoli and cauliflower. Place the broccoli and cauliflower in a large pot filled with one inch of water then sprinkle salt over the vegetables. Cover the pot with a lid and set it over high heat.
  3. Bring the water to a boil, lower and simmer for about two to three minutes or until the broccoli turns bright green. Turn off the heat.
  4. Drain the water and transfer the broccoli back into the pot. Set it aside and leave it covered for an additional three to four minutes to steam the vegetables until they are tender to the bite. Remove the cover to stop the cooking.
  5. Layer fresh baby kale on the bottom of an 8×8 Pyrex baking dish and spread evenly.
  6. Transfer the steamed vegetables on top of the baby kale. Scatter grated Parmesan cheese on top and add the cheddar cheese. Drizzle the heavy cream over the vegetables.
  7. Season with fresh cracked pepper to taste.
  8. Place the uncovered baking dish into the oven. Bake for 10 minutes or until the cheeses are completely melted and the cream has slightly thickened.
  9. Remove the baking dish from the oven. Set aside for a few minutes to cool down before serving.

Broccoli-kale white cheddar soup

This warming soup combines broccoli and kale with white cheddar.

Ingredients for 5-6 servings:

  • 6 cups broccoli
  • 4 cups vegetable broth (homemade broth recommended)
  • 4 cups water
  • 3 cups cauliflower
  • 2 cups kale
  • 1 cup sharp shredded white cheddar cheese
  • 2 tablespoons olive oil
  • 1 small-medium bulb fennel (or small-medium onion)
  • 2-4 cloves garlic, minced
  • 1/2 teaspoon paprika
  • 1/4 teaspoon red pepper flakes (Optional)
  • 1/4 teaspoon salt
  • Pepper to taste


  1. Heat a large pot over medium heat.
  2. Slice and dice the fennel (or onion), then add the olive oil and fennel to the pot. Saute for six minutes or until soft and fragrant, then add the minced garlic and saute all of it for another minute.
  3. In a separate pot, bring the water and vegetable broth to a boil.
  4. Chop all the cauliflower and broccoli stems into chunks, then add them to the sauteed fennel and garlic. Add the salt, hot broth and water.
  5. Set aside the broccoli florets.
  6. Return the mixture to a boil, then reduce to a simmer. Simmer for about six minutes or until the cauliflower and broccoli stems are somewhat soft, then add the broccoli florets and simmer for another two to three minutes, or until they’re also soft and bright green but not mushy and discolored.
  7. Pull the kale leaves from the stems. Discard the stems and roughly chop the leaves. Place the leaves in the blender.
  8. When all the vegetables are soft, remove them from the heat.
  9. Scoop about one to two cups of liquid from the pot and add to the blender with the kale. Blend on high for about one minute, or until the kale is pureed completely. Then add more soup and vegetables to the blender, then process in batches until smooth.
  10. Return the soup to the pot and add the cheddar. Keep the pot warm until the cheese melts, then season with the freshly ground black pepper, paprika, red pepper flakes and salt.

Eat cruciferous veggies like broccoli, cauliflower and kale to boost your immune health.


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