Research shows that 26% of individuals have experimented with juice cleanses or detox products. However, short-term juice consumption may impact the composition of gut and oral microbiota.

In a new dietary intervention study published in Nutrients, researchers from Northwestern University recruited 14 participants (7 males, and 7 females; mean age = 22.7 years). The participants followed one of three diets for 3 days: an exclusive juice diet (800 to 900 kcal/day of cold-pressed juice), a juice plus food diet (cold-pressed juice with an unrestricted diet), or a plant-based whole-food diet (800 to 900 kcal/day). Saliva, cheek, and stool microbiota samples were collected at baseline, after a preintervention elimination diet, postintervention, and 14 days later.

The saliva microbiome exhibited the most pronounced changes, with the exclusive juice diet associated with an increase in Proteobacteria and a decrease in Firmicutes. Similar trends were observed in the juice plus food group, which showed increased Proteobacteria and decreased Firmicutes and Actinobacteria. The researchers noted that these shifts may have reflected changes in bacterial communities that metabolize simple sugars; however, the clinical significance remained uncertain.

Gut microbiota changes were less pronounced. Although no significant shifts in overall composition were observed, the exclusive juice diet group exhibited trends toward increased relative abundances of Porphyromonadaceae and Rikenellaceae, bacterial families previously linked to gut permeability and inflammation in separate studies. The findings of this study did not reach statistical significance.

"These findings suggest that short-term juice consumption may negatively affect the microbiota, likely [as a result of] reduced fiber and the higher sugar and carbohydrate content," the study authors concluded, noting that their research may have implications for "redefining dietary recommendations and improving food production."

The study was limited by its small sample size and short intervention period. The researchers recommended larger, longer-term studies to validate the findings.

The authors declared no conflicts of interest.