Background: High fruit intake is known to be associated with reduced risk of coronary heart disease. Our objective was to determine the effects of acute and chronic juice [grapefruit, orange, and pineapple] intake on plasma lipid profile and lipoprotein metabolism in normolipidemic rats.
Material/methods: The effects of acute juice intake were studied after three hours of a single juice-lipid load instilled intragastrically. In the chronic study, blood samples from fasted animals were subjected to analyses after six months of either water [control] or water-juice [1:1] intake.
Results: In the acute study, pineapple and grapefruit significantly decreased plasma triacylglycerol [TAG], and chylomicron [CM] TAG and cholesterol concentrations concomitantly with delayed gastric emptying. Plasma cholesterol levels and very-low-density lipoprotein [VLDL] secretion and metabolism were not affected. In the chronic study, only grapefruit significantly decreased plasma and VLDL TAG concentrations and relative VLDL particle size with respect to other groups. All juices significantly increased VLDL apolipoprotein B [apoB] secretion, but plasma total apoB concentrations were highest in the grapefruit group and lowest in the orange and pineapple groups. No effect on blood cholesterol levels was observed.
Conclusions: The cardioprotective benefit of chronic juice intake in normolipidemic rat may be chiefly through mechanisms independent of a direct effect on blood lipid profile, although orange and pineapple, but not grapefruit, relatively improved the metabolism and clearance of blood lipoprotein particles. As a result of delayed gastric emptying, grapefruit and pineapple juices may moderate sharp increases in postprandial plasma TAG concentrations accompanying peak digestion and absorption.