Effects on cardiovascular risk factors of a low- vs high-Glycemic Index Mediterranean Diet in high cardiometabolic risk individuals: The MEDGI-Carb Study

Abstract

Background The role of dietary Glycemic Index (GI), independently of fiber intake, in modulating cardiovascular disease (CVD) risk among non-diabetic individuals has not been fully elucidated. Objective To evaluate the effects of a low- versus a high-GI diet, based on a Mediterranean dietary pattern, on cardiometabolic risk factors in individuals at high CVD risk, participating in the MEDGI-Carb intervention study. Subjects and methods : 160 individuals, aged 30–69 years, BMI 25–37 kg/m2, with a waist circumference > 102 cm (males) or > 88 cm (females) and one feature of the metabolic syndrome, participated in a multi-national (Italy, Sweden, USA) randomized controlled parallel group trial. Participants were assigned to a low GI (< 55) or high-GI MedDiet (> 70) for 12 weeks. The diets were isoenergetic and similar for available carbohydrate (270g/d) and fiber (35g/d) content. Fasting metabolic parameters were evaluated in the whole cohort, while an 8-hour postprandial triglyceride profile was evaluated only in the Italian cohort. Results Blood pressure and most fasting metabolic parameters improved at the end of MedDiet intervention (time effect, p < 0.05 for all); however, no differences were observed between the low- and the high-GI MedDiet groups (time x group effect; p > 0.05 for all). Conversely, the low-GI diet, compared with high-GI diet, significantly reduced postprandial triglycerides (iAUC) after lunch (-80%; p = 0.013). Conclusions Consuming a low-GI in comparison with a high-GI MedDiet does not differentially affect any of the cardiometabolic risk factors at fasting in individuals at increased cardiometabolic risk. Conversely, the low-GI diet reduces the postprandial plasma triglyceride profile. Clinical Trial Registry Number: NCT03410719, (https://clinicaltrials.gov).