The Role of Grapefruit Consumption in Cardiometabolic Health in Overweight and Obese Adults

Abstract

Atherosclerotic cardiovascular diseases (CVD) are the leading cause of death and often develop due to obesity-induced complications including hyperlipidemia, elevated blood pressure (BP), inflammation, and oxidative stress. Epidemiological, animal model, and cell culture studies indicate that citrus, and grapefruit specifically, exert cardiovascular health benefits, likely due to the high flavonoid content in citrus fruits. Grapefruit and/or isolated grapefruit flavonoids elicit cardiovascular benefits via improvements in lipid metabolism and endothelial reactivity, and by antioxidant and anti-inflammatory actions. The aim of this work was to determine the role of six-week daily consumption of grapefruit on weight, lipid, and BP control as well as inflammatory and oxidative stress markers in overweight/obese adults. Further, we sought to evaluate the acute, postprandial effects of grapefruit consumption on metabolic, inflammatory, and oxidative stress markers in response to a high fat, high calorie (HFHC) double meal challenge. Participants were randomized to either a grapefruit group (n=42) in which they consumed 1.5 grapefruit/day for six weeks or to a control condition (n=32). Ten participants who completed the feeding trial also participated in the postprandial study. On two test days participants consumed a HFHC meal for breakfast and again for lunch. A ruby red grapefruit was consumed with breakfast on the first test day. Blood samples were collected at baseline and for the subsequent eight hours on each day. In the feeding trial, grapefruit consumption resulted in reductions in waist circumference (p<0.001), systolic BP (p=0.03), total cholesterol (p=0.001), and LDL-cholesterol (p=0.021) compared to baseline values. F2-isoprostanes and hsCRP values were nonsignificantly lower in the grapefruit vs. control arm following the intervention (p=0.063 and p=0.073, respectively). In the postprandial evaluation, insulin concentrations were significantly higher 30 minutes (p=0.007) and 2 hours (p=0.025) post HFHC + grapefruit meal consumption vs. HFHC alone. HFHC + grapefruit intake resulted in lower IL-6 concentrations after two hours (p=0.017) and lower F2-isoprostanes after 5 hours (p=0.0125). These findings suggest that regular grapefruit consumption may reduce CVD risk by targeting many of the risk factors and pathogenic factors involved in endothelial dysfunction. However, this dietary change alone is unlikely to result in significant CVD risk reduction.