Gut Check: Feeding the Immune System

by Julie Peterson

Reducing stress, sleeping enough, exercising and getting sunlight are all known strategies for improving the body’s ability to protect itself from harm. However, the most important factor in building a rock-star immune system is nutrition. Here is a guide to the care and feeding of the inner fortifications that fight off disease, supporting long-term wellness.

About 70 percent of the immune system resides in the gastrointestinal tract—home to a microbiome that contains trillions of bacteria. It works as a complex ecosystem in which the good bacteria prevent the bad bacteria from taking hold and causing illness or disease.

Eating plants promotes the robust growth of that good bacteria. “The GI microbiome evolved closely with our immune systems and under the influence of the plants our ancestors ingested,” says Holly Poole-Kavana, who practices herbal medicine in Washington, D.C. Yet about 90 percent of Americans don’t eat enough fruits and vegetables, according to the U.S. Centers for Disease Control and Prevention. The consequent weakening of the microbiome is a double-edged sword, because the processed foods Americans commonly consume promote the growth of harmful microbes. The 2015-2020 Dietary Guidelines for Americans indicates that added sugars, saturated fats and sodium eaten by most Americans are far above recommended amounts. This tipping of the scales causes weight gain, toxin buildup and immune system dysfunction. 

Plants and grains on grocery shelves today are typically processed into bread, cereal, pasta, desserts and snacks, abundant in added sugars, salt, detrimental fats and chemical additives. These altered foods slam the gut’s immune protection and increase the risk of chronic disease. A Czech Republic study on food additives found that gut microbes that fought inflammation were harmed by additives. According to the research, “Permanent exposure of human gut microbiota to even low levels of additives may modify the composition and function of gut microbiota, and thus influence the host’s immune system.”

And of course, be wary of sugars. Anything that turns into sugar in the system—think carbs like refined bread products and pasta, not just sweets—is an immune-depressing culprit, says Heather Tynan, a naturopathic doctor at Evergreen Naturopathic, in San Diego. “The level of germ-fighting activity your immune system is able to maintain after a sugary meal decreases for a number of hours.” Saturated fats also alter immune cells, disrupting their functions and triggering inflammation.

Getting away from processed food cravings can be a challenge, because the foods provide a temporary energy boost. Dorothy Calimeris, of Oakland, California, a certified health coach and author of three anti-inflammatory cookbooks, suggests that cravings mean the body needs something, but it may be rest or water. “By focusing on eating higher-quality nutrients, we can limit and eventually eliminate the cravings.”

Fruits and vegetables get their colors from phytochemicals, which provide the human microbiome with antioxidants, minerals and vitamins that keep the gut healthy and help the immune system combat cellular damage. National guidelines suggest Americans eat 10 servings of plants a day, ideally two each from the green, red, white, purple/blue and orange/yellow categories. But data from the National Health and Nutrition Examination Surveys show that eight out of 10 people in the U.S. don’t get enough of any color category.

“A good strategy is to add one new vegetable a week to your grocery cart,” suggests Canadian nutritionist Lisa Richards, founder of the Candida Diet. “Blending fruits and vegetables into shakes or smoothies is also an effective way to eat the rainbow for those who are busy.”

Whatever goes into the grocery cart should be certified organic, the only sure way to avoid ubiquitous genetically modified organisms (GMOs) in the food chain, which animal studies have linked to immune system damage.

Herbs are also helpful to boost the body’s inherent ability to protect itself. Poole-Kavana points to medicinal herbs like astragalus and reishi mushroom, which support immunity and balance gut bacteria; antimicrobial herbs like garlic, thyme and oregano; and elderberry, an anti-inflammatory fruit that boosts the body’s ability to identify and eliminate viruses and bacteria.

“The single greatest thing anyone can do for their health is to eat whole foods, including organic vegetables, fruits, high-quality proteins, whole grains and healthy fats,” says Calimeris.

Turmeric is the darling of the anti-inflammatory spices. For best absorption, it should be combined with pepper. This soup gets its creamy texture from coconut milk, but other nondairy milk can be used instead.

Yields: 4 servings

2 Tbsp extra-virgin olive oil or coconut oil
1 leek, white part only, thinly sliced
3 cups cauliflower florets
1 garlic clove, peeled
1¼-inch piece fresh ginger, peeled and sliced
1½ tsp turmeric
½ tsp salt
¼ tsp freshly ground black pepper
¼ tsp ground cumin
3 cups vegetable broth
1 cup full-fat coconut milk
¼ cup finely chopped fresh cilantro

In a large pot, heat the oil over high heat. Add the leek, and sauté until it just begins to brown, 3 to 4 minutes.

Add the cauliflower, garlic, ginger, turmeric, salt, pepper and cumin, and sauté to lightly toast the spices, 1 to 2 minutes. Add the broth and bring to a boil.

Reduce the heat to a simmer and cook until the cauliflower is tender, about 5 minutes.

Using an immersion blender, purée the soup in the pot until smooth.

Stir in the coconut milk and cilantro, heat through, and serve.

Total cooking time is about 15 minutes.

Excerpted from the book The Complete Anti-Inflammatory Diet for Beginners: A No-Stress Meal Plan with Easy Recipes to Heal the Immune System, by Dorothy Calimeris and Lulu Cook.

Most stews take hours to cook, but this restorative dish, perfect for dinner or lunch, cooks up in a hurry. The plant-based recipe takes advantage of canned lentils and is loaded with nutritious, anti-inflammatory power foods.

Yields: 4 to 6 servings

1 Tbsp extra-virgin olive oil
1 onion, chopped
3 carrots, peeled and sliced
8 Brussels sprouts, halved
1 large turnip, peeled, quartered and sliced
1 garlic clove, sliced
6 cups vegetable broth
1 (15-oz) can lentils, drained and rinsed
1 cup frozen corn
1 tsp salt
¼ tsp freshly ground black pepper
1 Tbsp chopped fresh parsley

In a Dutch oven, heat the oil over high heat.

Add the onion and sauté until softened, about 3 minutes.

Add the carrots, Brussels sprouts, turnip and garlic, and sauté for an additional 3 minutes.

Add the broth and bring to a boil. Reduce to a simmer and cook until the vegetables are tender, about 5 minutes.

Add the lentils, corn, salt, pepper and parsley, and cook for an additional minute to heat the lentils and corn.

Total cooking time is about 15 minutes. Serve hot.

Another tip: This soup is as versatile as it is simple. Feel free to use any kinds of beans or vegetables you have—it’s a great way to use up leftover vegetables at the end of the week. Store in a covered container in the refrigerator for a week, or in the freezer for longer.

Nutritional information per serving
(4 portions): calories: 240; total fat: 4g;
total carbohydrates: 42g; sugar: 11g; fiber: 12g; protein: 10g; sodium: 870mg

Excerpted from the book The Anti-Inflammatory Diet One-Pot Cookbook: 100 Easy All-in-One Meals, by Dorothy Calimeris and Ana Reisdorf.