Bioactive compounds in orange juice help control blood sugar, study suggests

This was the main finding of a study by scientists affiliated with a FAPESP-supported research center. The effect may be associated with a mechanism whereby the fruit increases expression of an insulin-related microRNA.

By Thais Szegö  |  Agência FAPESP – A study conducted at the University of São Paulo (USP) in Brazil suggests that bioactive compounds found in oranges help modulate blood sugar levels, potentially making the fruit an ally in combating diabetes. An article on the findings is published in the journal Clinical Nutrition ESPEN.

The study was conducted by a group of researchers affiliated with the Food Research Center (FoRC), a Research, Innovation and Dissemination Center (RIDC) funded by FAPESP and hosted at the School of Pharmaceutical Sciences (FCF-USP).

The study sample consisted of 12 healthy male and female volunteers. After fasting for a night, they consumed a high-fat high-carbohydrate meal worth 1,037 calories (kcals), with which each of three groups drank water, orange juice, or a glucose beverage with the same calorific value as the orange juice.

Blood sugar was measured one, three and five hours after the volunteers broke their fast. In the first measurement, as expected, it rose in all three groups. Curiously, all three measures of blood sugar and insulin levels in the group that drank orange juice did not differ significantly from those of the group that drank water.

“If it made no difference whether orange juice or water was ingested, we can conclude that the carbohydrate in orange juice didn’t produce a significant increase in blood sugar in our experimental model, in contrast with the glucose drink,” said Bruna Jardim Quintanilha, first author of the article. Quintanilha is studying for a PhD in nutrition at the School of Public Health (FSP-USP).

This result, she added, suggests that other components of orange juice such as fiber and bioactive compounds might have prevented a rise in blood sugar. The researchers next investigated how this could have happened by analyzing blood samples from the volunteers to see how they expressed microRNAs, which regulate gene expression by interacting with messenger RNA.

“We found orange juice to act above all on microRNA miR-375, a biomarker of pancreas beta-cell function,” said Franco Lajolo, Emeritus Professor at FCF-USP and a member of the FoRC team.

Beta cells, which account for more than half the cells in pancreatic islets, secrete insulin, the hormone that controls blood sugar.

The study, therefore, showed that orange juice can have a beneficial effect on insulin production and blood sugar regulation. “We concluded that miR-375 could be responsible, but this must be confirmed in further research, such as studies involving diabetic patients to understand exactly how the mechanism works,” Lajolo said.

The article “Ingestion of orange juice prevents hyperglycemia and increases plasma miR-375 expression” is at: clinicalnutritionespen.com/article/S2405-4577(21)01149-9/pdf#%20.