A low-glycaemic index (GI) diet, based on a Mediterranean dietary (MedDiet) pattern, provides no substantial impact on major cardiometabolic risk factors at fasting in individuals at high cardiometabolic risk when compared with a high-GI MedDiet, a study has shown.
On the other hand, a low-GI MedDiet may help lower postprandial plasma triglycerides.
This randomized controlled parallel group trial was conducted in Italy, Sweden, and the US and included 160 participants (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.
Participants were randomly assigned to either a low-GI (<55) or a high-GI (>70) MedDiet for 12 weeks. These diets were isoenergetic and similar for available carbohydrate (270 g/d) and fibre (35 g/d) content. The investigators assessed the fasting metabolic parameters in the entire cohort and examined the 8-h triglyceride profile (after standard breakfast and lunch) in the Italian cohort only.
Improvements were observed in blood pressure and several fasting metabolic parameters at the end of the dietary intervention (time effect, p<0.05 for all), but no differences were seen between the low- and the high-GI MedDiet groups (time x group effect, p>0.05 for all).
In contrast, the low-GI MedDiet resulted in a significant decrease in the 8-h triglyceride profile (time x group effect, p<0.017) that was measured in the Italian cohort. However, this prompted a decrease in plasma triglycerides after lunch, with only a borderline statistical significance (p=0.065).