Quality versus quantity of fat in the diet affects development of diabetes

A new study examines the role of palmitic acid and oleic acid—among the main fatty acids in the diet—in the development of type 2 diabetes mellitus, a chronic condition associated with high morbidity and mortality worldwide. The research, published in Trends in Endocrinology & Metabolism, is led by teams from the CIBER Area for Diabetes and Associated Metabolic Diseases (CIBERDEM) at the University of Barcelona.

“Palmitic acid, a saturated fatty acid widely found in foods, is associated with impaired insulin sensitivity, whereas oleic acid, abundant in olive oil, may have a protective effect against these metabolic disorders,” says Professor Manuel Vázquez-Carrera, from the UB’s Faculty of Pharmacy and Food Sciences, the UB Institute of Biomedicine (IBUB), the Sant Joan de Déu Research Institute (IRSJD) and CIBERDEM.

Also contributing to the study are experts Ricardo Rodríguez-Calvo, a researcher at CIBERDEM at the Pere Virgili Institute for Health Research (IISPV); Marta Tajes, a researcher at the CIBER Area for Cardiovascular Diseases (CIBERCV) at the Bellvitge Biomedical Research Institute (IDIBELL), and Walter Wahli, from the University of Lausanne (Switzerland).

“This review highlights the significant role of the quality of dietary fat, rather than the total amount consumed,” notes Professor Manuel Vázquez-Carrera, who is a group leader at CIBERDEM at the UB.

As Xavier Palomer (UB-IBUB-CIBER-IRSJD), the article’s first author, says, “at the molecular level, palmitic acid promotes the accumulation of potentially toxic bioactive lipids, fosters low-grade chronic inflammation, and contributes to the dysfunction of cellular organelles, such as the endoplasmic reticulum and the mitochondria.” The researchers add that these processes “are closely linked to impaired insulin action and the progression of metabolic disease.”

A protective profile associated with oleic acid

Oleic acid, on the other hand, has a more favorable metabolic profile. As the article notes, this fatty acid, which is abundant in olive oil, promotes the storage of lipids in more metabolically inert forms—with minimal impact on physiological processes—and helps to preserve proper insulin signaling in key tissues such as the liver, muscle and adipose tissue.

Furthermore, oleic acid may counteract many of the adverse effects caused by palmitic acid, which would explain why dietary patterns rich in monounsaturated fats, such as the Mediterranean diet, are consistently associated with a lower risk of type 2 diabetes and other metabolic diseases.

Towards more precise nutritional strategies

The article highlights the need to move towards more targeted studies that can shed light on discrepancies observed in epidemiological studies. “It is important to consider variables such as the source of fatty acids, their dietary context, interactions with other nutrients, and different food processing methods,” says Manuel Vázquez-Carrera.

The team argues that a better understanding of these factors will enable a more accurate assessment of the actual impact of different types of fat on metabolic health and will help develop more effective nutritional strategies for the prevention and management of type 2 diabetes.