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Starchy foods are digested faster and produce higher postprandial glycemia in people with higher α-salivary amylase gene copy number.
Salivary α-amylase gene (AM1) copy number (CN) correlates with the amount of salivary amylase. Researchers tested the hypotheses that people with higher AM1 CN would digest starchy foods faster and show higher post prandial response and lower breath hydrogen excretion compared to those with low CN1. Four linked studies were conducted examining glucose tolerance, insulin sensitivity, BMI and macronutrient intake. Results found AMY1 CN did not correlate with BMI, glucose tolerance or insulin sensitivity. It was, however, strongly correlated with normalised glycemic responses to all starchy foods, but not to sucrose (sugar) or fruit. Individuals with the highest AMY1 CN produced modestly higher glycemia but not insulinemia after eating two starchy foods. Individuals with low AMY1 CN showed >6 fold higher breath methane after starch ingestion than high-CN individuals (suggesting starch maldigestion or malabsorption).
Atkinson F, Hancock D, Petocz P, Brand-Miller J. The physiological and phenotypic significance of variation in human amylase copy number. The American Journal of Clinical Nutrition, Volume 108, Issue 4, 1 October 2018, Pages 737–748. https://doi.org/10.1093/ajcn/nqy164