Low-carbohydrate diets reduce lipid accumulation and arterial inflammation in guinea pigs fed a high-cholesterol diet

Introduction: Low-carbohydrate diets (LCD) efficiently induce weight loss and favorably affect plasma lipids, however, the effect of LCD on atherosclerosis is still argued. Objective: To evaluate the effect of LCD on the prevention of atherosclerosis. Methods: Twenty guinea pigs were fed either a LCD or a low-fat diet (LFD) in combination with high-cholesterol (0.25 g/100 g) for 12 weeks. The percentage energy of macronutrient distribution was 10: 65: 25 for carbohydrate: fat: protein for the LCD, and 55: 20: 25 for the LFD. Plasma lipids were measured using colorimetric assays. Plasma and aortic oxidized (oxLDL) were quantified using ELISA methods. Inflammatory cytokines were measured in aortic homogenates using an immunoassay. H&E stained sections of aortic sinus and Schultz stained sections of carotid arteries were examined. Results: LDL cholesterol was lower in the LCD compared to the LFD group (71.9 +/- 34.8 vs. 81.7 +/- 26.9 mg/dL; p = 0.039). Aortic cholesterol was also lower in the LCD (4.98 +/- 1.3 mg/g) compared to the LFD group (6.68 +/- 2.0 mg/g); p < 0.05. The Schultz staining method confirmed less aortic cholesterol accumulation in the LCD group. Plasma oxLDL did not differ between groups, however, aortic oxLDL was 61% lower in the LCD compared to the LFD group (p = 0.045). There was a positive correlation (r = 0.63, p = 0.03) between oxLDL and cholesterol concentration in the aorta of LFD group, which was not observed in LCD group (r = -0.05, p = 0.96). Inflammatory markers were reduced in guinea pigs from the LCD group (p < 0.05) and they were correlated with the decreases in oxLDL in aorta. Conclusion: These results suggest that LCD not only decreases lipid deposition, but also prevents the accumulation of oxLDL and reduces inflammatory cytokines within the arterial wall and may prevent atherosclerosis. (C) 2009 Elsevier Ireland Ltd. All rights reserved.