Lard: Healthy or not? Lipids hold the answer

I. Background of the Study

Obesity and obesity-associated diseases, such as type 2 diabetes mellitus and cardiovascular diseases, have reached pandemic levels worldwide and are major threats to human life. Lipid species within adipose tissue, such as plasmalogen, cardiolipin, lysophosphatidic acid and fatty acid esters of hydroxy fatty acids (FAHFAs), play crucial roles in regulating thermogenesis and energy balance. Recent studies have mainly focused on physiological lipid function as a component of adipose tissue for maintaining metabolic homeostasis. However, whether the lipid composition and nutritonal quality of adipose tissue relates to its “beigeing” capacity (the ability of white adipocytes to acquire thermogenic properties similar to brown adipocytes) is worth being studied in detail.

Recently, Prof. Shan Tizhong's team at Zhejiang University discovered that lard derived from subcutaneous adipose tissue (SAT), as a dietary fat, offers better health benefits. They identified phosphatidylserine (PS), a differential lipid, which can regulate mitochondrial function and energy metabolism in adipocytes. Their findings, titled "Dietary 'Beigeing' Fat Contains More Phosphatidylserine and Enhances Mitochondrial Function while Counteracting Obesity", were recently published in Research.

 II. Progress of the Study

In this study, the researchers investigated the function of fats extracted from adipose tissues with different “beigeing” properties in the ketogenic diet and identified lipid profiles of lards that facilitate energy expenditure. They discovered that the anti-obesity effect of ketogenic diets was potentiated by using “beigeing” fat (SAT) as major energy-providing ingredient. Through lipidomic analyses, PS was identified as functional lipid activating thermogenesis in adipose tissue. Moreover, in vivo studies showed that PS induces adipose tissue thermogenesis and alleviates diet induced obesity of mice. In vitro studies showed that PS promotes UCP1 expression and lipolysis of adipocytes. Mechanistically, PS promoted mitochondrial function in adipocytes via ADCY3-cAMP-PKA-PGC1α pathway. In addition, PS-PGC1a binding may affect the stability of the PGC1α protein, which further augments PS-induced thermogenesis.

III Future Directions

These findings provide new insights into the metabolic consequences of lipid compositional heterogeneity and the regulatory role of exogenous PS supplementation for mitochondrial function, suggesting that lard derived from porcine SAT provides greater health benefits than that from VAT (Visceral adipose tissue), and that PS could serve as a promising nutritional therapy to counteract obesity and related metabolic diseases.