Resistant starch supplementation does not improve glycaemic control in prediabetic adults
Supplementation with resistant starch for 12 weeks decreases the inflammatory marker tumour necrosis factor [TNF]-α and heart rate but does not significantly improve glycaemic control and other cardiovascular disease risk factors in prediabetic adults, suggests a study.
A total of 68 overweight adults (body mass index [BMI], ≥27 kg/m2) aged 35–75 years with prediabetes were randomly assigned to consume either 45 g/d of high-amylose maize (RS2) or an isocaloric amount of the rapidly digestible starch amylopectin (control) for 12 weeks.
The investigators measured ectopic fat depots (visceral adipose tissue, intrahepatic lipids and intramyocellular lipids) by magnetic resonance imaging/spectroscopy, energy metabolism by respiratory chamber, and carbohydrate metabolism by glycated haemoglobin, an intravenous glucose tolerance test and a meal tolerance test at baseline and postintervention.
The following cardiovascular risk factors were also measured: serum lipids, blood pressure, heart rate, and inflammatory markers (high-sensitivity C-reactive protein [hs-CRP], interleukin-6 and TNF-α).
Insulin sensitivity, insulin secretion, ectopic fat and inflammation markers were the primary endpoints. The investigators analysed data primarily as treatment effects via a linear mixed model both with and without the addition of covariates.
RS2, as compared to the control group, reduced HbA1c by a clinically insignificant 0.1±0.2 percent (Δ, −1±2 mmol/mol; p=0.05) but did not affect insulin secretion, insulin sensitivity, the disposition index, or glucose or insulin areas under the curve relative to baseline (p≥0.23).
Relative to patients in the control group, those in the RS2 had reduced heart rate by 5±9 beats/min (p=0.02) and TNF-α concentrations by 2.1±2.7 pg/mL (p=0.004). Ectopic fat, energy expenditure, substrate oxidation and all other cardiovascular risk factors were not affected (p≥0.06).