Polyphenols are a group of bioactive compounds found in plant-based foods that have beneficial effects in the body. Bacteria in the human gut break down polyphenols into smaller compounds to increase their absorption. Authors of a recent study aimed to measure the relationship between gut health and the absorption of beneficial polyphenols in older adults.
As humans age, the quality of the population of microbes that comprise the gut microbiota decreases, leading to poor gut barrier integrity and causing contents of the gut to leak into the bloodstream, a condition commonly referred to as “leaky gut.” This leaking of toxins, viruses, and bacteria is associated with increased inflammation and disease risk. In addition to causing a leaky gut, poor microbiota quality may decrease the beneficial effects of polyphenol-rich plant foods.
The authors tested the effects of a polyphenol-rich diet in 51 adults (greater than 60 years of age) residing in an assisted living setting. Participants consumed either the normal menu prepared by their facility for eight weeks or a menu that included three servings of polyphenol-rich fruits, teas, and cocoa for eight weeks and then switched to the opposite diet. The researchers collected blood samples to measure serum zonulin, a marker of gut barrier integrity, and urine samples to analyze polyphenol metabolite content before and after each diet period.
Overall, serum zonulin decreased following eight weeks of a polyphenol-rich diet, meaning that gut barrier integrity improved. Participants who started the trial with better gut barrier integrity had a significantly greater increase in blood levels of polyphenol metabolites compared to participants with leakier guts. The metabolites found in the group with greater gut barrier integrity were microbial-derived, suggesting these participants had a more health-promoting gut microbiota.
Based on these results, the authors hypothesize that changes in the gut microbiota damage the gut barrier and cause a subsequent reduction in the absorption of dietary polyphenol compounds. They conclude that personalized diet plans could be effective for managing leaky gut in older adults.