The effect of flaxseed powder on insulin resistance indices and blood pressure in prediabetic individuals: A randomized controlled clinical trial

BACKGROUND: Designing the effective and early interventions can prevent progression of prediabetes to diabetes. Few studies have shown the effect of flaxseed on glycemic control. This study aimed to assess the effect of flaxseed powder on insulin resistance (IR) indices and blood pressure in prediabetic individuals. MATERIALS AND METHODS: In a randomized clinical trial, 99 prediabetic individuals were randomly divided into three groups: two groups received 40 g (FG40) and 20 g (FG20) flaxseed powder daily for 12 weeks and the third group was the control (CG). Before and after the intervention, anthropometric measurements, blood pressure, fasting serum glucose (FSG), insulin, homeostasis model assessment IR index (HOMA-IR), beta-cell function, and insulin sensitivity were measured. RESULTS: FSG significantly declined overall in all groups compared to the baseline (P = 0.002 in CG and FG20 groups and P = 0.001 in FG40). In contrast, mean of the changes in FSG was not significantly different between groups. Insulin concentration did not change significantly within and between the investigated groups. Although HOMA-IR reduced in FG20 (P = 0.033), the mean of changes was not significant between the three groups. Mean of beta-cell function increased in CG and FG40 groups compared to the baseline (P = 0.044 and P = 0.018, respectively), but mean of its changes did not show any difference between the three groups. The mean of changes in IR indices was not significant between the three groups. FG40 group had significantly lowered systolic blood pressure after the intervention (P = 0.005). CONCLUSION: Daily intake of flaxseed powder lowered blood pressure in prediabetes but did not improve glycemic and IR indices.