Making a bowl of chicken soup for a loved one when they are sick has been a common practice around the world for centuries. Today, generations from virtually every culture swear by the benefits of chicken soup. In the US, the dish is usually prepared with noodles, but each culture prepares this calming remedy in its own way.
Chicken soup as therapy dates back to 60 AD. and Pedanius Dioscorides, an army surgeon who served under the Roman emperor Nero, and whose five-volume medical encyclopedia was consulted by early healers for more than a millennium. But the origins of chicken soup date back thousands of years earlier, to ancient China.
So, with cold and flu season in full swing, it's worth asking: Is there any scientific basis to support the belief that it helps? Or does chicken soup only serve as a comforting placebo, that is, providing a psychological benefit while we are sick, without an actual therapeutic benefit?
As a registered dietitian and professor of dietetics and nutrition, I know well the appeal of chicken soup: the heat of the broth and the rich flavors of the chicken, vegetables, and noodles. What gives soup its characteristic flavor is "umami", the fifth category of taste sensations, along with sweet, salty, sour and bitter. It is often said to have a "meaty" flavor.
This all makes sense, because amino acids are the building blocks of proteins, and the amino acid glutamate is found in umami-flavored foods. However, not all umami foods are meat or poultry; cheese, mushrooms, miso and soy sauce also have it.
Studies show that flavor is essential to the healing properties of chicken soup. When I see patients with upper respiratory diseases, I notice that many of them suddenly eat less or do not eat at all. This is because acute illnesses trigger an inflammatory response that can decrease appetite. Not feeling like eating means the person is unlikely to get the nutrients they need, which is not optimal for immune health and recovery from illness.
But evidence suggests that the umami flavor of chicken soup may help stimulate a greater appetite. Participants in one study said they felt hungrier after first trying a soup with umami flavor added by researchers.
Other studies claim that umami can also improve the digestion of nutrients. Once the brain perceives umami through the taste receptors on the tongue, the body prepares the digestive tract to absorb proteins more easily.
This can reduce the gastrointestinal symptoms that many people experience when they are unwell. Although most people do not associate upper respiratory infections with gastrointestinal symptoms, research in children has found that the flu virus increased symptoms of abdominal pain, nausea, vomiting, and diarrhea.
Inflammation is part of the body's natural response to injury or illness; It occurs when white blood cells migrate to inflamed tissue to contribute to its healing. When this inflammatory process occurs in the upper respiratory tract, it results in common cold and flu symptoms, such as a stuffy or runny nose, sneezing, coughing, and thick mucus.
Conversely, lower white blood cell activity in the nasal passages can reduce inflammation. More interestingly, research shows that chicken soup can actually reduce the number of white blood cells traveling to inflamed tissues. It does this by directly inhibiting the ability of neutrophils, a type of white blood cell, to travel to inflamed tissue.
To truly understand the calming and healing effects of chicken soup, it is important to consider its ingredients. Not all chicken soups are packed with nutritious healing properties. For example, ultra-processed canned versions of chicken soup, both with and without noodles, lack many of the antioxidants found in homemade versions. Most canned versions of chicken soup have virtually no vegetables.
The essential nutrients in homemade versions of the soup are what differentiate them from canned ones. Chicken provides the body with a complete source of protein to fight infections. Vegetables provide a wide range of vitamins, minerals and antioxidants. When prepared the American way, noodles provide a source of easily digestible carbohydrates that the body uses for energy and recovery.
Even the heat of chicken soup can help. Drinking the liquid and inhaling the vapors increases the temperature of the nasal and respiratory passages, loosening the thick mucus that often accompanies respiratory illnesses. Compared to hot water alone, studies show that chicken soup is more effective at loosening mucus.
Herbs and spices sometimes used in chicken soup, such as pepper and garlic, also loosen mucus. The broth, which contains water and electrolytes, helps rehydrate.
So, to maximize the health benefits of chicken soup, I recommend a homemade variety, which can be made with carrots, celery, fresh garlic, herbs and spices, to name a few ingredients. But if you need a more convenient option, look at the ingredients and nutrition facts label, and choose soups with a variety of vegetables instead of an ultra-processed, nutrient-depleted one.
In short, the latest scientific discoveries suggest that chicken soup - although not a definitive cure for colds and flu - actually helps heal. Looks like grandma was right again.
This article was originally published on The Conversation website. You can read the text by University of Dayton nutrition and dietetics professor Colby Teeman at this link.
