As food is digested and nutrients released, islet cells in the pancreas secrete insulin to usher blood sugar into the body’s cells to be used as energy. The major driver of insulin secretion is glucose, produced when carbohydrates are broken down. However, the effect that the other main classes of macronutrients – proteins and fats – have on insulin production remains relatively underexplored.
Now, researchers from the University of British Columbia (UBC) in Canada have conducted the first large-scale study comparing how different people produce insulin in response to each of the three macronutrients and found that for some, proteins and fats have a stronger effect than glucose.
“Glucose is the well-known driver of insulin, but we were surprised to see such high variability, with some individuals showing a strong response to proteins, and others to fats, which had never been characterized before,” said James Johnson, a professor of cellular and physiological sciences at UBC and co-corresponding author of the study. “Insulin plays a major role in human health, in everything from diabetes, where it is too low, to obesity, weight gain and even some forms of cancer, where it is too high. These findings lay the groundwork for personalized nutrition that could transform how we treat and manage a range of conditions.”
Between 2016 and 2022, the researchers measured insulin secretion in response to carbohydrates (glucose), proteins (amino acids), and fats (fatty acids) from pancreatic islet cells taken from 140 deceased male and female donors, who reflected the general population. Comprehensive protein and gene expression analysis was performed on the cells.
While, as expected, the majority of donor cells showed the highest insulin response to glucose, a surprising 9% of cells had amino acid responses, and 8% had fatty acid responses that were larger than their glucose-stimulated insulin responses.
“This research challenges the long-held belief that fats have negligible effects on insulin release in everyone,” said Jelena Kolic, a research associate in the Johnson Lab at UBC and the study’s lead and co-corresponding author. “With a better understanding of a person’s individual drivers of insulin production, we could potentially provide tailored dietary guidance that would help people better manage their blood sugar and insulin levels.”
The researchers also examined a subset of islet cells from donors with type 2 diabetes. Unsurprisingly, the cells had a low insulin response to glucose. However, the cells’ insulin response to proteins remained largely intact.
“This really bolsters the case that protein-rich diets could have therapeutic benefits for patients with type 2 diabetes and highlights the need for further research into protein-stimulated insulin secretion,” Kolic said.
In future, genetic testing could be used to determine whether someone’s insulin response is triggered by a particular nutrient, the researchers say. In the meantime, they hope to continue their research by conducting clinical studies in healthy people and those with type 2 diabetes to test the insulin response to macronutrients in a real-world setting.
The study was published in the journal Cell Metabolism.
Source: UBC