Effects of resistant starch on blood pressure and autonomic function in women with the risk of metabolic syndrome: A randomized double-blind pilot study

ObjectiveResistant starch is associated with metabolic benefits, but whether autonomic regulation links resistant starch intake to cardiovascular outcomes remains unclear. This study examined the effects of resistant starch on heart rate variability and blood pressure in women with features of metabolic syndrome.MethodsIn this 8-week randomized, double-blind pilot trial, 30 women (aged ≥ 40 years) with ≥2 metabolic syndrome components were assigned to a high-resistant starch or low-resistant starch group. The primary outcome was the change in systolic blood pressure from baseline to week 8. Secondary outcomes included heart rate variability-related autonomic parameters, whereas other blood pressure and metabolic syndrome-related variables were evaluated as exploratory outcomes.ResultsSystolic blood pressure decreased significantly within the high-resistant starch group (p = 0.037), although the baseline-adjusted between-group difference was not statistically significant. This change occurred without corresponding improvements in body mass index or triglyceride levels. Group-level heart rate variability differences did not reach statistical significance; however, exploratory analyses suggested a favorable directional pattern in global heart rate variability composite scores among participants with lower baseline autonomic activity (p = 0.06).ConclusionsHigh-resistant starch intake demonstrated exploratory signals of reduced systolic blood pressure and heart rate variability-related autonomic adaptation, particularly among participants with lower baseline autonomic activity. These findings warrant confirmation in adequately powered randomized controlled trials.