High endogenous salivary amylase activity is associated with improved glycemic homeostasis following starch ingestion in adults

Abstract

In the current study, we determined whether increased digestion of starch by high salivary amylase concentrations predicted postprandial blood glucose following starch ingestion. Healthy, nonobese individuals were prescreened for salivary amylase activity and classified as high (HA) or low amylase (LA) if their activity levels perminute fell 1 SD higher or lower than the groupmean, respectively. Fasting HA (n = 7) and LA (n = 7) individuals participated in 2 sessions during which they ingested either a starch (experimental) or glucose solution (control) on separate days.Blood sampleswere collected before, during, and after the participants drank each solution. The samples were analyzed for plasma glucose and insulin concentrations as well as diploid AMY1 gene copy number. HA individuals had significantlymore AMY1 gene copies within their genomes than did the LA individuals.We found that following starch ingestion, HA individuals had significantly lower postprandial blood glucose concentrations at 45, 60, and 75 min, as well as significantly lower AUC and peak blood glucose concentrations than the LA individuals. Plasma insulin concentrations in the HA group were significantly higher than baseline early in the testing session, whereas insulin concentrations in the LA group did not increase at this time. Following ingestion of the glucose solution, however, blood glucose and insulin concentrations did not differ between the groups. These observations are interpreted to suggest thatHAindividualsmay be better adapted to ingest starches,whereas LA individualsmay be at greater risk for insulin resistance and diabetes if chronically ingesting starch-rich diets. © 2012 American Society for Nutrition.