Dietary Fruit and Vegetable Supplementation Suppresses Diet-Induced Atherosclerosis in LDL Receptor Knockout Mice

Abstract

Background: Epidemiologic studies suggest that fruit and vegetable (F&V) consumption is inversely associated with incidence of cardiovascular disease (CVD). However, evidence for causality is lacking, and the underlying mechanisms are not well understood.

Objectives: We aimed to determine whether there is a causal relation between consuming high levels of F&V and prevention of atherosclerosis, the hallmark of CVD pathogenesis. Furthermore, the underlying mechanisms were determined.

Methods: Six-week-old male LDL receptor-knockout mice were randomly assigned to 3 diet groups (12 mice/group) for 20 wk: control (CON, 10% kcal fat, 0.20 g/kg cholesterol), atherogenic (Ath, 27% kcal fat, 0.55 g/kg cholesterol), and Ath supplemented with 15% F&V (Ath + FV) (equivalent to 8-9 servings/d in humans). F&V was added as a freeze-dried powder that was prepared from the 24 most commonly consumed F&Vs in the United States. Body weight, aortic atherosclerotic lesion area, hepatic steatosis area, serum lipid profile and proinflammatory cytokine TNF-α concentrations, gut microbiota, and liver TNF-α and fatty acid synthase (Fasn) mRNA concentrations were assessed.

Results: F&V supplementation did not affect weight gain. Mice fed the Ath + FV diet had a smaller aortic atherosclerotic lesion area (71.7% less) and hepatic steatosis area (80.7% less) than those fed the Ath diet (both P < 0.001) independent of impact on weight, whereas no difference was found between Ath + FV and CON groups in these 2 pathologic markers. Furthermore, F&V supplementation prevented Ath diet-induced dyslipidemia (high concentrations of serum TG and VLDL cholesterol and lower concentrations of HDL cholesterol), reduced serum TNF-α concentration (by 21.5%), suppressed mRNA expression of liver TNF-α and Fasn, and ameliorated Ath-induced gut microbiota dysbiosis.

Conclusions: Our results indicate that consuming a large quantity and variety of F&Vs causally attenuates diet-induced atherosclerosis and hepatic steatosis in mice. These effects of F&Vs are associated with, and may be mediated through, improved atherogenic dyslipidemia, alleviated gut dysbiosis, and suppressed inflammation.

Keywords: LDL receptor knockout mice; atherosclerosis; dyslipidemia; fruits and vegetables; gut microbiota; hepatic steatosis; inflammation.