PhD research reveals potential role of Stevia in inducing satiety hormones
20 June 2016 – Rebaudioside-A, responsible for the sweetness of Stevia, might induce the release of gut hormones involved in feelings of satiety. This is just one of the conclusions from Dr Nikkie van der Wielen’s PhD research. Her results provide future directions to investigate the role of Stevia in preventing or treating obesity and (pre-)diabetes.
Secretion of gut hormones, such as satiety-inducing GLP-1, is usually influenced by nutrient ingestion. Dietary components interact with receptors and transporters in the enteroendocrine cells of the intestinal tract, inducing the release of these hormones – a process called nutrient sensing.
Van der Wielen examined these processes, studying hormone release in vitro. “Cell lines are not always representative of how the intestine works in vivo; cell lines usually represent only one cell type, whereas in the intestine different cell types are present, possibly interacting with each other”, she says. The PhD fellow developed an alternative approach, using organoids. “These are miniature, cultured intestines more similar to normal intestines”, she explains. “We have developed an organoid method that allows easy stimulation with nutrients and measurement of their hormone secretion.”
Van der Wielen observed that gene expression of receptors, transporters and peptides involved in nutrient sensing, showed a distinctive distribution pattern along the small intestine. “In mice, pigs and humans, similarity was highest in the distal intestine”, she says. In people who had lost weight after bariatric surgery, the nutrient sensing-related gene expression in the proximal (upper) part of the gastrointestinal tract saw only minimal changes. There was, however, considerable reduction in inflammatory pathways.
Van der Wielen’s work confirmed that rebaudioside-A from Stevia induces the release of GLP-1, an intestinal hormone that induces feelings of satiety and increases insulin release. “The effects appeared not to be mediated via the sweetness receptor”, she stresses, “we still aim to discover the receptor involved and are currently looking at some bitter-taste receptors.”
Van der Wielen, currently working as a post-doc scientist at Wageningen University, is happy to have worked for TiFN. “It is a very stimulating environment, with a lot of opportunities for extra courses and training, and close collaboration with other PhD fellows and food industries.”