Psyllium Fiber and Postprandial Peptide Release!!!

An estimated 4 million Americans use psyllium products daily. Psyllium is rich in dietary fiber, which is the most satisfactory prophylactic and treatment for functional constipation. Dietary fiber increases the mass of stools, their water content, and the rate of colonic transit. Psyllium has traditionally been used as a bulk-forming laxative; however, recent research points to other uses including hypercholesterolemia, irritable bowel syndrome, and ulcerative colitis. In February, 1998, the FDA gave permission to allow food manufactures to make a health claim on the packaging of food products regarding psyllium. The claim reads: “Eating soluble fiber from foods such as psyllium as part of a diet low in saturated fat and cholesterol may reduce the risk of heart disease.” These findings make psyllium a potential agent for reducing the risk of cardiovascular disease.

Postprandial means after eating a meal and is pertinent to diabetes, endocrinology, gastroenterology, metabolism, pathology, and many other biomedical fields. It is used in relation to blood sugar levels which are measured 2 hours after eating.

Dietary fiber and protein are important parts of a healthy diet and have a high satiety impact, which can be very critical in weight management. A single-blind, randomized, cross-over study, published in the Journal of Nutrition, sought to investigate the effects of dietary fiber (psyllium fiber was used) and protein on postprandial peptide release and hunger ratings in 16 healthy, non-obese volunteers. The subjects were given 1 of 5 meals in randomized order in separate days and serum insulin and plasma glucose, ghrelin, glucagon-like peptide 1 (GLP-1), and peptide YY (PYY) concentrations were determined two hours following the meals. The test meals included one that was low in fiber and protein, the next was low in protein, but high in fiber, the third was high in protein, but low in fiber, the fourth meal was high in both protein and fiber and the last meal consisted of white wheat bread. The results revealed that meals containing high amounts of fiber decreased glucose, insulin, ghrelin, and PYY responses. It was determined that PYY secretion was longer after high fiber meals compared with the other meals. The researchers also discovered that postprandial GLP-1 concentration was significantly suppressed after a fiber- and protein-rich meal, in contrast to the initial increases following the other meals. However, they did not find any difference in satiety ratings between the different test meals. These results suggest that meals enriched with psyllium fiber seem to strongly modify postprandial signals arising from the GI tract.¹

¹ Karhunen LJ, Juvonen KR, Flander SM, et al. A psyllium fiber-enriched meal strongly attenuates postprandial gastrointestinal peptide release in healthy young adults. J Nutr. Apr2010:140(4):737-44.