Effects of the dietary carbohydrate–fat ratio on plasma phosphatidylcholine profiles in human and mouse

Abstract

Phosphatidylcholines (PCs), a major class of human plasma phospholipids, are composed of highly diverse fatty acids. Because the dietary carbohydrate–fat ratio alters the hepatic fatty acid metabolism, plasma fatty acids that bind PCs, which are secreted as lipoproteins from the liver, may be affected by long-term consumption of a high-carbohydrate diet or a high-fat diet. Therefore, in this study, we profiled the plasma PC species comprehensively in formulated dieting conditions to identify those phospholipid molecules that reflect the dietary carbohydrate–fat ratio. C57BL6J mice were fed diets containing different amounts of fat for 8 weeks, and plasma PC species were analyzed under fasting conditions using liquid chromatography–mass spectrometry. In addition, a cross-sectional study of 78 middle-aged Japanese men, who participated in health checkups, was conducted. Nutrient intakes were estimated by a brief self-administered diet-history questionnaire. The plasma PC profiles changed depending on the dietary carbohydrate–fat ratio. Especially, PC (16:0/16:1) and PC (16:0/18:1) levels increased as the dietary carbohydrate–fat ratio increased in human and mouse, suggesting that these PC species reflected the increase in de novo lipogenesis and might become useful biomarkers of the dietary carbohydrate–fat ratio. Since these PCs act as ligands for peroxisome proliferator-activated receptor α, PC species reflecting the dietary carbohydrate–fat ratio may influence metabolism of glucose and lipids.