A novel wheat variety with elevated content of amylose increases resistant starch formation and may beneficially influence glycaemia in healthy subjects

BACKGROUND Previous studies indicate that elevated amylose content in products from rice, corn, and barley induce lower postprandial glycaemic responses and higher levels of resistant starch (RS). Consumption of slowly digestible carbohydrates and RS has been associated with health benefits such as decreased risk of diabetes and cardiovascular disease. OBJECTIVE To evaluate the postprandial glucose and insulin responses in vivo to bread products based on a novel wheat genotype with elevated amylose content (38%). DESIGN Bread was baked from a unique wheat genotype with elevated amylose content, using baking conditions known to promote amylose retrogradation. Included test products were bread based on whole grain wheat with elevated amylose content (EAW), EAW with added lactic acid (EAW-la), and ordinary whole grain wheat bread (WGW). All test breads were baked at pumpernickel conditions (20 hours, 120°C). A conventionally baked white wheat bread (REF) was used as reference. Resistant starch (RS) content was measured in vitro and postprandial glucose and insulin responses were tested in 14 healthy subjects. RESULTS The results showed a significantly higher RS content (on total starch basis) in breads based on EAW than in WGW (p<0.001). Lactic acid further increased RS (p<0.001) compared with both WGW and EAW. Breads baked with EAW induced lower postprandial glucose response than REF during the first 120 min (p<0.05), but there were no significant differences in insulin responses. Increased RS content per test portion was correlated to a reduced glycaemic index (GI) (r=-0.571, p<0.001). CONCLUSIONS This study indicates that wheat with elevated amylose content may be preferable to other wheat genotypes considering RS formation. Further research is needed to test the hypothesis that bread with elevated amylose content can improve postprandial glycaemic response.