Fresno, CA – A new clinical study published in the scientific journal Nutrients found that consuming grapes significantly increased the diversity of bacteria in the gut which is considered essential to good health overall. Additionally, consuming grapes significantly decreased cholesterol levels, as well as bile acids which play an integral role in cholesterol metabolism. The findings suggest a promising new role for grapes in gut health and reinforce the benefits of grapes on heart health.
In the intervention study, conducted at the University of California, Los Angeles, and led by principal investigator Zhaoping Li, M.D., Ph.D., healthy subjects consumed the equivalent of 1.5 cups of grapes per day – for four weeks. The subjects consumed a low fiber/low polyphenol diet throughout the study. After four weeks of grape consumption there was an increase in microbial diversity as measured by the Shannon index, a commonly used tool for measuring diversity of species. Among the beneficial bacteria that increased was Akkermansia, a bacteria of keen interest for its beneficial effect on glucose and lipid metabolism, as well as on the integrity of the intestinal lining. Additionally, a decrease in blood cholesterols was observed including total cholesterol by 6.1% and LDL cholesterol by 5.9%. Bile acids, which are linked to cholesterol metabolism, were decreased by 40.9%.
“We found that grapes have a beneficial effect on gut bacteria, which is great news, since a healthy gut is critical to good health,” said Dr. Li. “This study deepens our knowledge and expands the range of health benefits for grapes, even as the study reinforces the heart health benefits of grapes with lowered cholesterol.”
 Yang, J., Kurnia, P., Henning, S.M., Lee, R., Huang, J., Heber, D., & Li, Z. (2021). Effect of standardized grape powder consumption on the gut microbiome of healthy subjects: a pilot study. Nutrients, 13(11), 3965.
 Whole grape powder used for research purposes.