Olive oil before carbs blunts blood sugar rise in mice, Japan study finds

Kyoto University researchers say eating olive oil before carbohydrates slowed gastric emptying and reduced glucose spikes in mice, but human trials are still needed.

Researchers in Japan have found that olive oil may blunt sharp rises in blood sugar when it is consumed before carbohydrates, although the evidence so far comes only from animal studies. The work, reported by Kyoto University and published in the journal Diabetes, suggests that the order in which foods are eaten may matter as much as the foods themselves when it comes to early glucose control.

In the experiments, mice were given olive oil before glucose. That sequence appeared to slow gastric emptying, the process by which the stomach passes food into the small intestine, and in turn reduced the initial surge in blood sugar that followed. The researchers also saw the effect in mice with type 2 diabetes, which points to a possible role for meal sequencing in people with impaired glucose regulation.

The underlying biology appears to involve several overlapping pathways. According to the researchers, the response was linked to gut hormones including GLP-1 and glucagon, as well as the vagus nerve, which carries signals between the digestive system and the brain. Together, these mechanisms seem to slow the movement of food out of the stomach and alter how quickly glucose enters the bloodstream.

The findings fit with earlier evidence that extra-virgin olive oil can soften the blood sugar rise after a meal. A randomised controlled trial published in Diabetes Care found that adding extra-virgin olive oil to high-glycaemic-index meals reduced post-meal glucose levels in patients with type 1 diabetes. Separately, nutrition researchers have long noted that fats in a meal can slow digestion and moderate the speed of glucose absorption.

Still, experts say the new results should be treated with caution. Both Kyoto University’s study and the related reporting by ScienceDaily stress that the effect has only been shown in mice, not in humans. That means any practical advice for people with diabetes or pre-diabetes will need to wait for clinical trials designed to test whether olive oil eaten before carbohydrates produces the same benefit in everyday diets.