Acute effect of equicaloric meals varying in glycemic index and glycemic load on arterial stiffness and glycemia in healthy adults: a randomized crossover trial.

BACKGROUND/OBJECTIVES: Dietary carbohydrate quality and quantity fluctuate but it is unknown which attribute takes precedence in vascular health preservation. We investigated all four permutations of glycemic index (GI) and glycemic load (GL) on acute vascular and glycemic responses.

SUBJECTS/METHODS: Twenty-one healthy adults were screened for this crossover trial. Seventeen (8 M:9 F; 26.7 ± 12.3 y; BMI 22.2 ± 2.8 kg/m2 ) entered randomization and completed the study, receiving four isocaloric meals, varying in GI and GL, in random order at least 3 days apart. The four meals included either chickpeas (GI = 28, GL = 14, 50 g available carbohydrates (CHO)), a small potato portion (GI = 85, GL = 14, CHO = 17 g), pasta (GI = 45, GL = 42, CHO = 94 g) or a large potato portion (GI = 85, GL = 42, CHO = 50 g) as the source of carbohydrate. Augmentation index (AIx) and central and peripheral blood pressure were measured fasting, 1, 2, 3, and 4 h post-consumption. Capillary blood glucose was analyzed fasting, 15, 30, 45, 60, 90, 120, 180, and 240 min.

RESULTS: A reduction in AIx from baseline was observed 4 h following the chickpeas (low GI-low GL) (p = 0.046). The incremental area under blood glucose curves were significantly higher 2 h post-consumption following high compared with low GL meals (p < 0.001). Despite doubling carbohydrates, there was no difference in glycemic response between the large potato (high GI-high GL) and the pasta (low GI-high GL) meals. No significant differences in AIx or blood pressure were seen between meals.

CONCLUSIONS: Low GI, low-carbohydrate meals may support a healthy vascular tone. Varying meal GI and GL results in different glycemic profiles, which are not necessarily predicted by carbohydrate content. Further investigations on cardiometabolic profiles to meals varying in GI and GL are warranted.