Mixed Fruits and Berries Improve Gut Microbiota and Attenuate Liver Alterations Induced by a Cafeteria Diet in Adolescent Rats
A 6-week controlled animal feeding study investigated whether a mixture of fruits and berries could reduce gut microbiome disruption and liver damage caused by a cafeteria-style diet, a high-fat, high-sugar diet designed to mimic ultra-processed human eating patterns, in adolescent male rats. Animals were divided into groups receiving a standard control diet, a cafeteria diet alone, or the cafeteria diet supplemented with mixed fruits and berries at two doses (3% or 6% of total diet). Supplementation was introduced either before, at the same time as, or after exposure to the cafeteria diet.
Researchers measured body weight gain, gut microbiome composition, short-chain fatty acids (beneficial compounds produced by gut bacteria), and markers of liver health, including fat accumulation, inflammation, and liver enzyme activity. Structural indicators of gut health, such as colon length, were also assessed.
The results showed that the cafeteria diet led to excess weight gain, reduced microbial diversity, and clear signs of liver fat accumulation and inflammation. Supplementation with mixed fruits and berries partially reversed these effects, reducing liver fat content, inflammatory markers, and histological signs of liver damage. The fruit-and-berry groups also showed improvements in gut microbiota composition, including higher relative abundance of beneficial bacteria such as Bifidobacterium and Akkermansia, along with increased production of short-chain fatty acids, particularly butyrate, which supports gut barrier integrity and anti-inflammatory signaling.
Importantly, benefits were observed even when fruit and berry supplementation was introduced after the cafeteria diet had begun, suggesting some capacity to mitigate ongoing diet-induced damage, not just prevent it. Higher doses generally produced stronger effects, though timing and dose both influenced outcomes.
These findings support the conclusion that polyphenol-rich fruits and berries can help protect gut health and reduce liver damage associated with poor dietary patterns, likely through combined effects on gut microbes and microbial metabolites that influence liver metabolism. The study also highlights limitations, including its animal model design and focus on adolescent rats, meaning results may not fully translate to humans.
Future research should examine similar dietary strategies in human populations, particularly during adolescence, and clarify optimal dosing and timing. Overall, this study reinforces the idea that whole-food, plant-based interventions can meaningfully influence the gut–liver axis, even in the context of highly processed diets.
