Kyoto University Researchers Find Olive Oil Blunts Blood Sugar Spikes in Mice

Researchers at Kyoto University discovered that administering olive oil before carbohydrates blunts early blood sugar spikes in mice by slowing gastric emptying and triggering a coordinated hormone and nerve response. The findings offer physiological insights into meal-sequencing strategies for managing post-meal glucose levels.

Controlling post-meal glucose spikes remains a primary therapeutic target in managing diabetes. While previous clinical studies suggest that eating vegetables, protein, or fat ahead of carbohydrates can moderate these glycemic surges, the underlying biological mechanisms—particularly involving neural pathways and gut hormones—have stayed largely unclear. An international team of researchers set out to clarify how the timing of fat intake influences hormone secretion, gastric emptying, and blood sugar levels.

Our group has long been interested in practical dietary approaches that people can continue in everyday life, said Daisuke Yabe, corresponding author from Kyoto University, pointing out that meal-sequencing changes how people eat rather than forcing them to banish entire food groups. Yabe further noted that meal-sequencing is appealing because it merely changes how a meal is consumed rather than requiring people to avoid entire food groups.

Kyoto University Researchers Find Olive Oil Blunts Blood Sugar Spikes in Mice — Photo: kyoto-u.ac.jp

How the Kyoto University Experiment Was Conducted in Mice

One group received plain water followed by glucose, a second group received olive oil followed by glucose fifteen minutes later, and a final group received glucose followed by olive oil fifteen minutes later. Following these feedings, the investigators tracked blood glucose alongside plasma levels of insulin, glucagon, GIP, and GLP-1.

To estimate gastric emptying rates, the team administered acetaminophen orally and measured subsequent blood acetaminophen concentrations. Additional experiments tested mice with type 2 diabetes, mice lacking GLP-1 receptors, subjects with inhibited glucagon or GLP-1 signaling, and animals that underwent bilateral sub-diaphragmatic vagus nerve ligation. Researchers also tested alternative dietary fats to confirm whether the observed metabolic responses were unique to olive oil.

Olive Oil Before Carbs Shock: What REALLY Happens To Your Blood Sugar

Hormonal and Neural Pathways Behind Lower Glucose Levels

The experiments showed that providing olive oil before carbohydrates rather than afterward successfully reduced the early rise in blood glucose while slowing down gastric emptying. Giving fats first also triggered an early release of glucagon, GIP, and GLP-1. Crucially, these beneficial effects were retained even in subjects with type 2 diabetes and severe insulin deficiency.

When the team tested signal inhibitions, they found that blocking either glucagon or GLP-1 signaling alone did not weaken the glucose-lowering benefit of the olive oil preload; only combined inhibition attenuated the response. This demonstrated that glucagon signaling—traditionally known for raising blood sugar—actively contributes to lowering glucose when paired with an olive oil preload. Vagus nerve ligation experiments indicated that vagal pathways are necessary to facilitate these metabolic shifts.

Our findings suggest that the order in which nutrients reach the gut can engage a coordinated hormone-nerve response that changes how quickly the stomach delivers glucose to the intestine, Yabe explained regarding how olive oil administered before carbohydrates elicits early glucagon and GLP-1 responses that act in a partially redundant manner and, with involvement of vagal pathways, slow gastric emptying and attenuate the early post-meal glucose. Daisuke Yabe, Kyoto University

By establishing a physiological baseline for how food order alters post-meal metabolism, the study strengthens the scientific backing for clinical trials evaluating practical meal-sequencing approaches in human populations with and without diabetes.