These five foods help boost prebiotics and maintain good gut health

Garlic, leeks, onions, dandelion greens and Jerusalem artichokes are the most prebiotic-rich foods available and could help boost gut health.

Prebiotics are a type of fibre that functions as a food source for probiotics – bacteria that help to maintain a healthy community of microbes in the gastrointestinal tract, which has been linked to the health of the immune system and even protection against some medical conditions.

To uncover the richest prebiotic food sources, Cassandra Boyd at San José State University, California, and her colleague John Gieng combed through 70 scientific papers on prebiotics in foods, nine of which contained a sufficient amount of data to be included in their analysis. From these, they analysed the prebiotic content of 8690 types of food.

The researchers found that the top five prebiotic-containing foods were, in descending order: dandelion greens, Jerusalem artichokes, garlic, leeks and onions, each of which contain between 100 and 240 milligrams of prebiotics per gram, as presented at Nutrition 2023 in Boston, Massachusetts, the annual meeting of the American Society for Nutrition.

The International Scientific Association for Probiotics and Prebiotics, in California, recommends a daily prebiotic intake of around 5 grams a day. This could be achieved by eating just half a small onion, said Boyd in a statement.

Other rich prebiotic sources include foods that contain these vegetables, such as onion rings and creamed onions, as well as asparagus and black-eyed beans, also known as cowpeas. But about 37 per cent of the foods analysed contain no prebiotics, with low scorers including wheat, dairy, eggs, oils and meats.

As well as potentially benefiting gut health, prebiotics are also a type of dietary fibre, which is good for digestion. Data shows fibre intakes are insufficient across every region of the world. “By consuming more prebiotic fibre, one is also consuming more fibre in general,” says Boyd.