The idea that we should eat 30 different plants a week has gained traction, but experts caution that it is not a magic number for gut health. The claim stems from a 2018 study involving more than 10,000 participants in the US, UK and Australia, who submitted stool samples and reported their typical diets. Researchers found that those who consumed more than 30 different plant foods per week tended to have a more diverse gut microbiome than those who ate fewer than 10.
Arbitrary Threshold
However, Prof Daniel M Davis, head of life sciences at Imperial College London and author of Immune Health: A Myth-Busting Guide, says the number 30 is arbitrary. “It’s not as though researchers compared 10 plants, 20 plants, 30 plants and 35 plants and found a clear cut-off point,” he explains. The study does not prove that eating 30 plants directly improves health; while a diverse microbiome is linked to lower disease risk, scientists still do not know what a truly healthy microbiome looks like.
Lifestyle Factors and Supplements
Davis notes that people eating more than 30 plants a week likely have many other healthy habits, such as exercise, good sleep and stress management, which also affect the microbiome. He warns against those using the “30 plants” message for profit, particularly the growing market for expensive supplements promising to help hit the target. “It hasn’t been proven that reaching 30 plants a week will prevent illness or lead to specific health benefits,” Davis says. “What we do know is that eating a variety of fruits, vegetables, legumes, nuts and wholegrains is generally good for you.”
