These 5 vegetables are the best sources of prebiotics, research shows

With the growing importance of gut health in nutrition, a new study has uncovered specific foods that provide the highest prebiotic content. The study also highlights the benefits of prebiotic intake in maintaining a healthy gut microbiome.

Presented at Nutrition 2023, the flagship meeting of the American Society for Nutrition, the study used existing literature to estimate the prebiotic content of thousands of food types, highlighting the foods with the highest prebiotic content.

Prebiotics, a type of fiber found in certain plant-based foods, stimulate beneficial bacteria in the gut, promoting overall wellness.

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These foods are not only beneficial for gut microbes but are also rich in fiber, an essential nutrient lacking in the diets of many Americans.

“Consumption of prebiotic-dense foods has been indicated by previous studies to have health benefits,” San Jose State University graduate student Cassandra Boyd, Ph.D., who led the study with assistant professor John Gieng, said in a statement.

“Eating in a way that promotes microbiome health while increasing fiber intake may be more achievable and accessible than you think.”

Prebiotics vs Probiotics

The distinction between prebiotics and probiotics is crucial to understanding their role in gut health. Prebiotics are food for the microbiome, while probiotics contain live microorganisms. Both can positively affect gut health but work differently.

Previous studies have linked higher prebiotic intake to better blood glucose control, improved mineral absorption (such as calcium), and better digestive and immune markers. Although current Dietary Guidelines do not specify a recommended daily allowance for prebiotics, the International Scientific Association for Probiotics and Prebiotics recommends consuming 5 grams per day.

To conduct the study, researchers analyzed the prebiotic content of 8,690 foods using the Food and Nutrition Database for Dietary Studies, a widely used resource in nutrition and health research. They found that about 37 percent of the foods in the database contained prebiotics. Top prebiotic-rich foods, including dandelion greens, Jerusalem artichokes, garlic, leeks, and onions, contain about 100 to 240 milligrams of prebiotics per gram of food (mg/g).

Other foods with significant prebiotic content include onion rings, creamed onions, cowpeas, asparagus, and Kellogg’s All-Bran Cereal, each containing about 50 to 60 mg/g.

“Findings from our preliminary literature review suggest that onions and related foods contain multiple types of prebiotics, leading to a greater total prebiotic content,” Boyd said.

“Multiple forms of onions and related foods appear as flavoring and main ingredients in a wide variety of dishes. These foods are commonly consumed by Americans and thus would be a potential target for people to increase their prebiotic consumption.”

Based on the team’s findings, Boyd says a person would need to eat about half a small (4-ounce) onion to get 5 grams of prebiotics.

And, notably, wheat-containing items ranked low on the list, while foods with little or no prebiotic content were dairy products, eggs, and animal products such as meat.

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The researchers hope that their study will lay the foundation for evaluating the health effects of prebiotics and formulating future dietary guidelines. However, they emphasized the need for more research to understand how cooking affects prebiotic content and to better evaluate multi-ingredient foods.

Plant protein for good gut health

As gut health continues to gain prominence in nutrition, the results of this study may pave the way for more personalized and effective dietary recommendations—and the importance of consuming plant-based foods—to support overall wellness and a healthy gut microbiome.

Another study published in a scientific journal Proceedings of the National Academy of Sciences A specific carbohydrate attached to plant protein has been found to be a prebiotic food source for our gut bacteria.

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While fruits and vegetables are the best sources of nutrients for a healthy gut microbiome (the collection of microbes that naturally live inside us), research has shown that one species of gut bacteria uses plant N-glycan—a type of complex carbohydrate found in plant foods—as nutrients.

“The gut microbiome is an incredibly important feature of human health, and this finding will enable us to better understand the microbiome,” study lead author Lucy Crouch said in a statement. “By identifying the specific enzymes these microbes use to digest their food, we may be able to develop future diets that promote a healthy gut and consequently improve our general health.”