Effect of Grapefruit Intake on Postprandial Plasma Glucose

Abstract

Objective: Previous epidemiological surveys of diet indicated a potential relationship between fruit intake and the pathogenesis of lifestyle-related disease. Recent reports indicate grapefruit (GF) may affect sugar metabolism. The present study measured glucose, triglyceride and insulin levels in human blood after GF ingestion with and without other foods. Methods: Twelve healthy, non-smoking female volunteers, non-obese (age 40.5 ± 4.2 years old, BMI 22.0 ± 0.9) were provided with five different breakfasts on successive days: GF, bread or fried vegetables alone, GF + bread, GF + fried vegetables. In meals that included GF, the GF was eaten before the bread or fried vegetables. Blood samples were taken after meals to measure plasma glucose, immuno reactive insulin (IRI), triglyceride and vitamin C. Results: Plasma glucose following a meal of bread or fried vegetables or a meal of bread and fried vegetables with GF was similar. Insulin secretion was slower after a meal of GF alone compared to bread alone (p < 0.001) and the area under curve (AUC) of glucose per carbohydrate intake was lower when GF was eaten prior to bread or fried vegetables than after a single intake of bread or fried vegetables alone (p < 0.001). The AUC of triglyceride after a prior intake of GF before fried vegetables was slower than that after an intake of fried vegetables alone (p < 0.05). Blood vitamin C concentration increased after GF intake (p < 0.001). Conclusion: GF contains saccharides and a variety of dietary elements, including fiber, vitamins, citric acid, naringenin and bergamottin. It is possible that these compounds may affect sugar and lipid metabolism.