Bariatric surgery improves atherogenic LDL profile by triglyceride reduction.

Background: Small dense low-density lipoprotein (LDL) are atherogenic particles frequently observed in obese patients. Fatty acids modulate LDL. Objective of this study was to determine the relations between plasma phospholipid fatty acid composition and the presence of small dense LDL particles in morbidly obese patients treated with laparoscopic gastric banding (LAGB).

Methods: Small dense LDL, plasma lipids, lipoproteins, apoproteins, and phospholipid fatty acid composition (a marker of dietary fatty acid intake) were quantified before and 12 months after surgery in four men and 11 women who were morbidly obese and (BMI > 40 kg/m(2)) eligible for surgery, consecutively treated with LAGB at the Department of Medical and Surgical Sciences of the University of Padova.

Results: BMI was 48.3 +/- 4.8 kg/m(2) before and 36.1 +/- 5.5 kg/m(2) after LAGB. Plasma triglycerides and apoprotein E levels significantly decreased, while HDL cholesterol significantly increased after LAGB. A reduction of small dense LDL with an increase of LDL relative flotation (0.34 +/- 0.04 before vs 0.38 +/- 0.03 after LAGB, p < 0.001) was also observed. These modifications were neither related to weight reduction nor to changes in phospholipid fatty acid composition, but they were associated to triglyceride reduction, which explained 76.7% of the LDL relative flotation variation.

Conclusion: Weight loss obtained by LAGB in morbidly obese subjects was accompanied by triglyceride reduction, high-density lipoprotein increase, and an improvement of the atherogenic LDL profile. Triglyceride reduction, but not the extent of weight loss or dietary fatty acid modifications, is the determinant of modifications of LDL physical properties in these patients.