Changes in low-density lipoprotein size phenotypes associate with changes in apolipoprotein C-III glycoforms after dietary interventions

Background The presence of small dense low-density lipoprotein (LDL) is associated with obesity, type II diabetes, and an increased risk for cardiovascular disease. Apolipoprotein C-III (apoC-III) is involved in the formation of small dense LDL, but the exact mechanisms are still not well defined. ApoC-III is a glycosylated apolipoprotein, with 3 major glycoforms: apoC-III 0 , apoC-III 1 , and apoC-III 2 that contain 0, 1, or 2 molecules of sialic acid, respectively. In our previous work, we reported an association among apoC-III 0 and apoC-III 1 , but not apoC-III 2 with fasting plasma triglyceride levels in obesity and type II diabetes. Objective The goal of this study was to determine the relationship between changes in the major apoC-III glycoforms and small dense LDL levels after dietary interventions. Methods Mass spectrometric immunoassay was performed on fasting plasma samples from 61 subjects who underwent either a high-carbohydrate diet ( n  = 34) or a weight loss intervention ( n  = 27). Results After both dietary interventions, changes in total apoC-III concentrations were associated with changes in LDL peak particle diameter ( r  = −0.58, P r  = −0.53, P  = .001), and decreases in apoC-III concentrations after weight loss were associated with increases in LDL peak particle diameter ( r  = −0.54, P  = .004). Changes in concentrations of apoC-III 1 and apoC-III 0 , but not apoC-III 2 , were associated with changes in LDL peak particle diameter in both the weight loss and high-carbohydrate interventions. Conclusions We conclude that apoC-III 0 and apoC-III 1 , but not apoC-III 2 are associated with the formation of small dense LDL.