Soup and Sunshine: Building a Better Immune System

Colorful fruits and vegetables—and easy-to-get vitamin D—can help you ward off illness
May 21, 2020 Updated: May 21, 2020

Physicians have often turned to food ingredients to help keep everyone’s immune system as healthy as possible.

Although not a proven cure, doctors in the 1400s recommended their patients include horseradish, mint, vinegar, and applesauce in their diets to ward off the bubonic plague. These ingredients do have some immune-boosting properties, including vitamin C, antioxidants, flavonoids, fiber, and water. Perhaps this is the origin of “an apple a day?”

In the 1600s, Parisian citizens’ thirst for lemonade may have helped to keep the plague out of their city. Lemonade was all the rage; mobile lemonade vendors circulated around the city, dispensing the popular beverage and discarding the citrus peels in the streets. The vitamin C, minerals, and water in the lemonade may have helped to keep the immune system healthy. Plague was spread by fleas from infected rodents. An unintended but helpful consequence was the insect-repelling properties of citrus peels.

Populations that had access to a variety of healthy foods did better during times of widespread disease. People’s diets assisted in building and maintaining healthy immune systems. Until recently, food intake was largely grain-based for many parts of the population, with fruit, vegetables, and meat considered to be “luxury foods.”

Information taken from interviews with survivors of the 1918 flu pandemic showed that people who had regular access to fresh fruits and vegetables, dairy, and protein foods, such as meat, eggs, seafood, or poultry, tended to fare better with recovery from the flu than those with a more restricted diet.

One survivor, interviewed when he was 100 years old, said: “My parents worked for a merchant family in Boston. There were always bananas, oranges, pineapples, and other types of ‘exotic’ fruit in their home, something unheard of at that time. We children were given the pick of one piece of fresh fruit a day; none of us got sick during the epidemic, and we all lived to be at least in our 90s.”

Healthy Choices, Healthy Immunity

Fast forward to today and our widely available assortment of fresh, frozen, canned, and dried immune-building food ingredients. According to Kathleen Zelman, dietitian and director of nutrition for WebMD, we should regularly eat berries, fatty fish, dark green leafy vegetables, whole grains, sweet potatoes, tomatoes, beans, nuts, and eggs for immune system support.

Fresh and dried herbs have been used in the kitchen forever, adding wonderful flavor, color, and health benefits to the foods we eat.

The digestive system plays an important role in immunity. It extracts vitamins and nutrients essential for creating different immune cells and fueling (or suppressing) our immune response. Eating poorly can also undermine immunity, such as sugar’s role in suppressing certain immune responses.

We should try to keep our digestive system as healthy as possible so it can assist with a healthy immune response. Rosemary, with aromatic leaves and flowers, is a natural antioxidant and can have an antibacterial effect on food, helping with digestive health.

Fresh chilies, cayenne, and bell peppers get their “heat” from a natural compound called capsaicin. Capsaicin was found to assist in maintaining stomach health, among several other benefits, according to a review of 78 studies published in Open Heart in 2015. Chopped fresh, frozen, or canned peppers add flavor and increase the health quotient of sauces, pasta, rice, and salads.

The Physician’s Committee for Responsible Medicine reminds us that the more fresh or frozen fruits and vegetables included in a dish, the more immune-enhancing ingredients we put on the plate.

Even without a nutritional analysis, we know that an eggplant stew with tomatoes, summer squash, garlic, onions, carrots, celery, and basil is providing immune benefits in addition to the pleasure of eating great-tasting food. Spinach fettuccini with a mushroom sauce, served with a red and green cabbage salad and fresh melon is filled with immune-enhancing ingredients, beautiful to the eye and satisfying to eat.

If you would like to obtain a fast nutritional analysis for your menu items, you can input ingredients into the USDA’s nutritional data bank online.

Chicken Soup for the Immune System

Most cultures have their version of Grandma’s chicken soup. In Greece, it’s avgolemono (chicken, rice, and lemon soup). In Iran, it’s Persian gundi (chicken meatball soup), and in Puerto Rico, it’s sancocho (chicken and root vegetable soup), while Peru has a chicken, hard-cooked egg, and noodle breakfast soup.

Science has confirmed the health benefits contained in this comforting meal, which help to bolster the immune system. But it’s not all about the chicken. The hot broth, carrots, onions, parsnips, dill, parsley, ground pepper, and additional herbs, veggies, and protein also play a role in flu-fighting.

From Scratch or Speed-Scratch

Homemade soup is an efficient and economical way to include lots of immune bolstering ingredients in one bowl. Peel and chop root vegetables, such as carrots, turnips, parsnips, sweet potatoes, or yellow, gold, or purple potatoes, add a small amount of canned broth or water, and let simmer in a pot or slow cooker until the vegetables are soft.

Puree all or most of the soup, reheat, and serve with a splash of vinegar, lemon, or lime juice or tomato paste. Leftover cooked or canned poultry, bacon, pasta, or tofu can be stirred into the soup for added protein and texture.

If you have the time, make some onion soup. Onions contain vitamin C and flavonoids, known to help with healthy immune reactions. Slice lots and lots of onions, spray a large pot with vegetable oil and quickly stir and sauté. The onions will create their own “juice.” When the onions have gotten very soft, add in vegetable or mushroom broth, allow to simmer, and, voila, onion soup.

If you don’t feel the urge to create “from scratch” soups, here are some ideas for “speed scratch” soups:

Split Pea and Lentil: Add cooked or canned drained lentils to canned split pea soup and dilute according to package directions. Add chopped onions and shredded ham, chopped hot dogs, cubed smoked tofu, or smoked turkey during cooking for more flavor.

Fast Fish Chowder: Thaw and chop frozen fish filets. Simmer with a small amount of broth and chopped carrots, celery, and onions. Add to canned cream of potato or cream of celery soup and allow to cook until hot and veggies are soft. Serve hot with cornbread muffins on the side.

Puree Mongole: A classic soup combination of tomatoes and split peas. Combine canned tomato soup and canned split pea soup with drained, chopped canned tomatoes, cook and stir until hot. Pair with crusty baked bread or herbed breadsticks.

Tomato-Corn Chowder: Combine canned tomato soup with canned corn chowder; dilute with milk, silken tofu, or a combination of plain yogurt and water. Add drained, chopped tomatoes and frozen or canned cut corn (drained) for extra texture. Pair with a small Caesar salad.

Putting the Chill on Soup

We can plan on chilled soups when the weather is warm. Chilled soups can be refreshing and luxurious, and easy to prepare when we don’t want to heat up the kitchen.

Traditional gazpacho has a tomato base. White gazpacho is popular and can have corn and zucchini or tofu base. Green gazpacho is a wonderful way to drink your greens. Create your red gazpacho base by pureeing tomatoes in a blender or food processor with sweet onions, fresh garlic, fresh parsley or basil, and a small amount of oil.

Create your white gazpacho base by pureeing fresh, steamed and chilled or frozen, thawed zucchini with some canned creamed corn (the “cream” is cornstarch, rather than dairy) and a small amount of silken tofu or plain yogurt.

Create your green gazpacho base by pureeing your fresh greens of choice; spinach, kale, and so on. Romaine lettuce and Swiss chard work well. Add a small amount of prepared pesto sauce. Once you have your base, you can add shredded fresh vegetables, fresh herbs, and seasonings to taste. If you’d like thicker gazpacho, crumble some fresh, crustless bread into the mix, blend, and allow to sit. The bread will create a thickened, smooth texture.

Create a pumpkin base for a cold soup by blending canned, unseasoned pumpkin with a very small amount of coconut milk. Cold pumpkin soup can be flavored with curry, pureed carrot, leftover mashed potatoes, orange or lemon zest, or pureed beans. Garnish with frozen grapes or chilled bell pepper slices.

Create a tofu base for a cold soup by blending silken tofu with fresh parsley, sweet onions, a small amount of tomato puree, garlic, onion powder, and white pepper.

Create cold potato chowder by adding cubed, leftover potatoes and mixed veggies, or shredded raw veggies to the tofu base.

Create a cold borscht by pureeing shredded fresh beets or drained, canned beets with the base. You can also create a Thai-inspired cold soup with lemongrass, orange zest, and fresh ginger, or a pesto-cream by blending with prepared pesto and cooked beans.

Balance and Sunshine

Spending time in the kitchen, at the stove, and at the table is a wonderful way to use part of our day. Getting out into the sunshine should also be on our daily “to do” list.

Starting with the advent of television, many children got accustomed to hearing “go outside for a while, you shouldn’t stay in all day.” There is some science behind this directive. In the late 1800s, children living in the sun-limited cities of Northern Europe and North America had a high incidence of developing rickets, a disease caused by vitamin D deficiency. They also had a tendency to contract tuberculosis (TB). Vitamin D was thought to assist the body in warding off TB, and we know it’s critical to helping our immune system differentiate disease-causing cells from healthy cells.

Sunshine is the best source of vitamin D, as the body is able to use UV light from the sun to create vitamin D in the body. According to the National Institutes of Health, UV light plays an important role in many of the body’s immune responses.

Human skin produces beta-endorphins when exposed to UVB.  These opioid peptides boost the immune system, relieve pain, and help us relax and feel well.

Endorphins are “feel-good” chemicals produced by the body, our own personal “cheerleaders.” Sunshine and exercise have been found to assist the body in producing endorphins. We should consider the wisdom of “going outside for a while,” without excessive sun exposure, to help boost our immune system and our spirits.

As the days grow longer and seasonal fruits and vegetables become more available, it’s a good time of year to get plenty of sun and the fresh fruits and vegetables that can get our immune system in shape for the coming cold season.

Dr. Nancy Berkoff is an international nutritionist, food technologist, and culinary professional. She divides her time between health care and culinary consulting, food writing, and healthy living.