The order in which we eat different parts of a meal may affect how quickly blood sugar rises afterward.
A new mouse study offers one possible reason why.
Researchers at Kyoto University found that mice given olive oil before glucose had a smaller early rise in blood sugar than mice given the oil afterward. The olive oil also slowed how quickly the stomach emptied.
The study, published in Diabetes, does not show that people should take olive oil before eating carbohydrates. It was done in mice and used glucose rather than a typical meal.
Still, the findings build on earlier human studies suggesting that eating vegetables, protein or fat before carbohydrates may help reduce post-meal blood sugar spikes.
“Meal-sequencing is appealing because it merely changes how a meal is eaten rather than requiring people to avoid entire food groups,” said corresponding author Daisuke Yabe of Kyoto University.
In the experiment, mice received either water followed by glucose, olive oil followed by glucose 15 minutes later or glucose followed by olive oil.
When the oil came first, blood sugar rose less sharply early on.
The researchers found that slower stomach emptying appeared to be part of the explanation. Hormone and nerve signals also seemed to contribute.
The effect was not limited to healthy mice. Researchers saw similar patterns in mice with type 2 diabetes and severe insulin deficiency, and other dietary fats produced similar results.
“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 said.
That helps explain how meal order might influence blood sugar, but it does not tell us how large the effect would be in people eating ordinary meals.
The study also did not test whether eating fat before carbohydrates improves long-term blood sugar control or leads to better health outcomes.
For now, the findings are best viewed as a closer look at why meal order may matter, not a new rule for how to eat.
The study was supported by KAKENHI and the Japan Society for the Promotion of Science, the Japan Association for Diabetes Education and Care, the Suzuken Memorial Foundation and the Japan Agency for Medical Research and Development.