Ileal starch digestibility and the postprandial glycemic response to faba beans in healthy humans.

Legumes are a sustainable protein source and a recommended starchy food in healthy diets. Resistant starch has shown beneficial effects on glycemic control. However, the digestibility of the starch, indicating the amount of resistant starch, in legumes has been poorly studied in humans. We aimed to assess the ileal starch digestibility from faba beans in healthy volunteers and the associated glycemic response. Nine healthy volunteers were equipped with a naso-ileal tube. They ingested 250 g of dehulled, cooked mashed faba beans as a test meal. Ileal contents, plasma and urine samples were collected regularly over an 8 h postprandial period. Respiratory exchanges were measured every hour. Residual starch in ileal effluents was measured after hydrolyzing samples with α-amylase. Intestinal and plasma glucose, plasma insulin as well as glucose oxidation were determined. The amount of starch ingested was 30.7 ± 1.7 g. In the terminal ileum, 6.4 ± 2.4 g of starch was recovered, resulting in starch digestibility of 79.1 ± 8.0 %. Postprandial glycemic response was weak, with a maximal value of 1.02 ± 0.11 g/L occurring at 1.5 h. Insulinemia slightly peaked at 84.2 ± 77.3 pmol/L at 1.5 h. Respiratory Quotient was stable (∼0.9) over time. Glucose oxidation was constant during the 8 h and amounted 80 ± 32 g. The observed low glycemic response after ingestion of faba beans, combined with their high resistant starch content, supports the established health benefits of legumes and aligns with the current public health policies that increasingly recommend the consumption of pulses.