A recent study by researchers at the University of California’s David Geffen School of Medicine reveals that eating grapes may have more benefits than previously thought. Published in the journal Nutrients, the study shows that grape consumption can boost gut biome diversity and reduce cholesterol levels.
Building on prior research, which has shown that fruits like apples and grapes are rich in polyphenols—antioxidants that support heart health—the new study expands on these benefits. Polyphenols are known to lower blood sugar and blood pressure, and may even reduce inflammation, a key contributor to heart disease.
In this new experiment, 19 healthy adults participated in a four-week trial. Initially, they followed a low-polyphenol, low-fiber diet. In the second phase, they added grape powder (46 grams per day, equivalent to two servings of grapes) to their diet. Researchers collected stool, blood, and urine samples at both stages to measure any changes.
The results were promising: after four weeks of grape powder supplementation, participants showed significant improvements in gut biome diversity—an important factor linked to a stronger immune system. Notably, the study observed an increase in Akkermansia bacteria, known for its positive effects on glucose metabolism and lipid balance.
In addition, participants saw a 6.1% reduction in total cholesterol and a 5.9% decrease in LDL (the “bad” cholesterol). There was also a significant drop in steroid acids in bile—down by 40.9%. These acids are involved in cholesterol metabolism, suggesting that grape consumption may play a role in improving cholesterol levels.
This research highlights yet another reason to include grapes in your diet, showing that they can support not only heart health but also a more diverse and resilient gut microbiome.
