Adding probiotics and vitamin D3 to daily 100% orange juice did not give people at high cardiometabolic risk a significant glucose-metabolism advantage over unfortified orange juice in an eight-week randomized trial, the authors concluded.
The finding is narrower than a claim that orange juice improves blood sugar. Both groups received orange juice, so the study tested whether fortification changed the results rather than what would happen without juice. The authors suggested that orange juice, with or without fortification, may be favorable for glycemic fluctuations, while concluding that the enriched drink did not significantly change glucose metabolism compared with the unfortified drink.
The comparison was between two juices
Fifty people completed the trial. Twenty-four were in the unfortified-orange-juice control group and 26 were in the FunJuice group. The report gives 17 males, or 34%, a reported age of 48.7 years and a reported BMI of 32 kg/m2.
Participants assigned to FunJuice drank 250 mL each day of orange juice containing 2,000 IU of vitamin D3 and the reported probiotics Lacticaseibacillus rhamnosus GG and Lacticaseibacillus casei Shirota. The control group drank 250 mL of unfortified orange juice daily. The double-blinded intervention lasted eight weeks.
Researchers assessed glucose with an oral glucose tolerance test, or OGTT, and continuous glucose monitoring, or CGM, which records glucose over time. The OGTT was performed at baseline and at eight weeks. CGM covered 14 days before the intervention and the final two weeks, giving the researchers a baseline window and a short end-of-trial window rather than readings across the entire intervention.
What the glucose readings showed
On the main between-group comparison, OGTT measures and most CGM-derived indices remained comparable. The reported result was p > 0.05, and the analysis did not report a statistically significant separation between the fortified and unfortified groups on those measures.
Some differences appeared in pairwise, before-and-after comparisons within groups. In the FunJuice group, the high blood glucose index fell by 0.06, with a reported interval from -0.1 to -0.02 and p = 0.010. That was a change within the enriched-juice group, not evidence that it outperformed the control.
Both groups also had reported decreases in 24-hour glucose AUC, a summary measure of glucose readings across a day. The change was -9 for the control group, with a reported interval from -14.5 to -3.5, and -8.9 for FunJuice, with an interval from -14.2 to -3.6. The reported p-value was 0.002 for each comparison.
At the same time, the control group's 30-minute glycemic response rose by a reported 20, with an interval from 5.6 to 34.4 and p = 0.007. Taken together, these results show that the reported glucose measures did not all move in one direction within the trial.
The boundaries of the finding
The authors' overall reading was that adding the probiotics and vitamin D3 did not produce significant changes in glucose metabolism relative to unfortified orange juice. Their more tentative suggestion about favorable glycemic fluctuations applied to orange-juice intake with or without fortification.
The findings have a limited reach. They describe 50 people who completed an eight-week, two-arm orange-juice trial, so they do not establish what would happen after longer use or in people outside the high-cardiometabolic-risk group.
Because both groups drank orange juice, the within-group declines and rises cannot establish that either drink caused them. The design can speak to the difference between fortified and unfortified juice, not to a no-juice alternative.
Uncertainty also remains around the reported statistics. The results give p-values and ranges for several pairwise comparisons, but the paper does not specify what type of interval those ranges represent, and it does not provide full estimates for the between-group effects.
Funding and access
The FunJuice project was co-financed by the EU and Greek National Funds through the RESEARCH CREATE-INNOVATE program. The authors declared no competing interests and reported that funders had no role in the study's design, data collection, analyses, interpretation, manuscript writing or publication decision.
The version of record was published on 20 August 2026. The study datasets are available from the corresponding author on reasonable request.
Paper data and sources
Original title: Effects of orange juice enriched with probiotics and vitamin D3 on glucose metabolism in high-cardiometabolic risk individuals: secondary outcomes of a randomised controlled trial.
Authors: Sofia Tsitsou, Nikolaos Zacharodimos, Stamatia Vitsou-Anastasiou et al.
Journal/Repository: European journal of clinical nutrition
Status: Peer-reviewed
First online: 2026-08-20
DOI: 10.1038/s41430-026-01808-0
Original paper · Full text