February 27, 2024

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Prebiotic food sources are just as important as probiotics in a healthy diet. Lynne317/Getty Images
  • Probiotics have become commonplace when looking to achieve a healthy diet.
  • Prebiotics are just as important as probiotics in building a healthy gut.
  • Researchers from San José State University have found five foods that naturally provide the biggest prebiotic “punch” for good gut health.
  • Onions and dandelion greens are among these five prebiotic-rich foods.

Over the last few years, the term “probiotics” has become commonplace when talking about one’s diet. A global industry survey found 80% of consumers take a probiotic every day.

Store shelves are full of probiotic supplements and some food manufacturers are even adding probiotics to their offerings.

In a show about a healthy gut, probiotics definitely steal most of the spotlight. However, prebiotics are an important co-star that people should know more about as they help ensure probiotics work efficiently.

And now, new research recently presented by San José State University at NUTRITION 2023, the flagship annual meeting of the American Society for Nutrition, reports the five foods that naturally provide the biggest prebiotic “punch.”

For this study, researchers evaluated the prebiotic information of 8,690 different types of foods contained in the Food and Nutrient Database for Dietary Studies.

Scientists reported about 37% of foods in the database contained prebiotics. The five foods with the highest prebiotic content — between 79-243 milligrams of prebiotic per gram of food — were:

“We weren’t surprised to find that these foods ‘packed the greatest prebiotic punch,’ per se, being as our previous literature review had shown these foods were high in prebiotics,” said Cassandra Boyd, master’s student and presenting author of the study, who conducted this research with Dr. John Gieng, assistant professor of nutritional sciences in the Department of Nutrition, Food Science & Packaging at San José State University.

“That being said, we were surprised by how relatively small portions of these foods contained the International Scientific Association for Probiotics and Prebiotics (ISAPP) recommended daily amount of prebiotics — 5 grams. For example, if a small onion tends to be around 4 ounces, then by consuming around half a small onion in a day one can consume the recommended 5 grams of prebiotics,” explained Boyd to Medical News Today.

Other prebiotic-rich foods found through the study include onion rings, creamed onions, cowpeas (also known as black-eyed peas), asparagus, and Kellogg’s All-Bran cereal. All of these foods contain around 50-60 milligrams of prebiotics per gram of food.

Researchers found wheat-containing foods ranked low in prebiotics. And dairy products, eggs, oils, and meat had little to no prebiotic content.

After reviewing this research, Allison Tallman, a registered dietitian and founder of Nourished Routes, told MNT it was not surprising that the five foods listed are high in prebiotics.

“These foods are also high in fiber, which is beneficial for gut health as well,” she continued. “I think individuals will be interested to learn more about dandelion and Jerusalem artichokes, given that these foods are potentially not as recognizable to the everyday consumer.”

Dr. Rosario Ligresti, chief of the Division of Gastroenterology at Hackensack University Medical Center, agreed.

“I was not surprised at all because each of these foods (has) been shown to have many health benefits, so it would make sense they are also good for our gut and our digestion,” he told MNT.

“Many of these foods, especially Jerusalem artichokes, are high in the indigestible dietary fiber inulin that, when broken down in the gut, release the healthy prebiotic nutrients that get to work to support our digestive health in so many ways.”
— Dr. Rosario Ligresti

Probiotics are microorganisms that people consume or apply to their bodies. As they are often the same “good” bacteria as live in your gut microbiome they are hoped to give health benefits such as helping digest food and assisting in keeping your entire body well-balanced.

Consuming things like certain medications, such as antibiotics, and alcohol can sometimes kill off helpful bacteria, leaving the individual with an unbalanced gut. Adding probiotics back into the body through supplements or eating probiotic-rich fermented foods such as yogurt, sauerkraut, kefir, and kimchi can help restore balance to the microbiome.

In order to stay alive, the “good” bacteria in the gut microbiome and any probiotic bacteria one consumes need something to eat. That’s where prebiotics come in.

Prebiotics are dietary fiber that is not digestible by the body. As they go through the digestive system, probiotics feed off of them to stay alive and grow.

“Prebiotics are healthy precisely because they have been indicated to improve the microbiome,” said Boyd. “They are substrates that beneficial bacteria can use directly to confer health benefits on the host, as these bacteria perform functions that are advantageous to human health.”

In addition to supporting probiotics, prebiotics are also known to help with:

Research is currently ongoing to evaluate how prebiotics may help people with certain diseases such as irritable bowel syndrome and obesity, as well as preventing certain cancers such as colorectal cancer.

As for the next steps in this research, Boyd said they plan to investigate if there is a relationship between prebiotic consumption and depression as evaluated by the validated instrument, the Patient Health Questionnaire (PHQ9).

Tallman said she would like to see more research on the consumption of these specific foods, as well as other prebiotic-dense foods, on the human microbiome.

“It would be interesting to have some randomized controlled trials done to see the actual health benefits of prebiotics on the human microbiome and to see its correlation with various disease states. There’s still a lot of research to be done on prebiotic consumption and the gut-brain connection, as well.”
— Allison Tallman, registered dietitian

And Dr. Ligresti commented while there is a lot of existing research to support that these foods are excellent prebiotic sources, you can never have enough large studies over long periods of time to support what we may already suspect.

“More research into the benefits of a healthy microbiome — promoted by these foods — are also warranted, especially how altering the microbiome might help cancer patients and patients who suffer from autoimmune diseases,” he added.

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