High glycemic index breakfasts affect heart health, a new study suggests

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A new study assessing the effects of high and low glycemic index (GI) breakfasts on the cardiovascular system found that the former can lead to increased arterial stiffness.
Arterial stiffness is an important determinant of heart function and atherosclerosis, a complication that may affect overweight adults and those with type 2 diabetes.
The study, conducted by scientists at the Biomedical Research Institute of Salamanca (IBSAL), in Spain, was a crossover trial that included 40 young healthy adults aged 20 to 40 years old.
These individuals didn’t have a history of cardiovascular disease, nor did they have high blood pressure, dyslipidemia or type 2 diabetes prior to starting the experiment.
The participants consumed three different breakfasts: the low GI (LGI) breakfast, the high GI (HGI) breakfast and a water only fasted meal in the control group.
Breakfast composition wise, the HGI breakfast (72 g of carbs) consisted of 200 mL of grape juice, two slices of white bread and 29 g of strawberry jam with a GI totalling 64.0.
The LGI breakfast (31.5 g of carbs) contained a 150 g apple, 125 g of low-fat natural yogurt, three walnuts and 17.5 g of 72% dark chocolate, which amounts to an overall GI of 29.4.
Blood glucose and insulin levels were measured after each breakfast, as were vascular parameters like heart rate (HR), (arterial) pulse pressures (PPs) and what’s known as the Augmentation index (AIx), which is simply a measure of arterial stiffness.
In the findings, published in the journal Nutrients, researchers report a trend toward increased AIx, HR and PPs with the HGI versus the LGI breakfast.
Furthermore, blood glucose values at 60 min after the HGI breakfast were significantly higher than those after the LGI breakfast. Insulin concentrations over 120 min were also greater with the HGI breakfast compared to the LGI breakfast.
The results are in line with previous research showing an association between GI and arterial stiffness in 1553 subjects who did not have heart disease.
For every increase of five GI units in the hitherto study, there was a 0.11% increase in AIx which, coupled with other factors, can be the sign of a deteriorating vascular function.
In contrast, LGI diets can help reduce cardiovascular risks by decreasing blood sugars, improving insulin sensitivity and lipids and promoting good vascular function.