Intake of beta-glucan changes satiety and markers of gut microbiota in healthy, normal weight individuals
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Background: Obesity is one of today´s major public health issues, and understanding the mechanisms that control human appetite has gained increased attention. Certain dietary fibres, such as beta-glucan, has been shown to stimulate gut-derived peptides involved in the regulation of appetite, and gut microbiota has been hypothesised to be involved in the regulation. In the current project, we aimed to investigate whether consumption of cereals with various content of beta-glucan affect satiety measures, and if the effects may be related to changes in the gut microbiota. Methods: Fourteen healthy men and women were enrolled in this fixed order cross-over intervention study. The subjects consumed cereals containing different amounts of beta-glucan (0.5 g (control), 3.5 g and 8 g), for three consecutive days as an evening meal. After consuming the meal on day one and day three, the subjects filled out a visual analogue scale (VAS). Circulating gut peptides (PYY and GLP-2) and short chain fatty acids (SCFAs) were measured the following day after each of the three interventions (day 4). Breath H2 was measured as an indirect measure of colonic fermentation. Gut peptides, SCFAs and breath H2 were measured fasting and after an oral glucose tolerance test (OGTT). Results: A three-day intervention with 8 g beta-glucan increased the fasting levels of PYY (P=0.001) compared with the control meal, and fasting levels of the SCFA butyrate (P=0.041) compared with the 3.5 g meal. 8 g of beta-glucan also increased PYY after the OGTT when compared with the control, and a positive correlation between butyrate and PYY were observed (r=0.430, P=0.004). GLP-2 did not change after any of the inteventions. Subjective satiety sensation was significantly decreased after day one with the 8 g meal compared with day one with the control meal (P=0.011). In addition, subjective satiety sensation was increased from day one to day three after intervention with the 8 g meal (P=0.08). Furthermore, fasting breath H2 concentrations increased after intake of the 8 g meal compared with the control meal (P=0.048). Conclusion: The present study demonstrates increased concentrations of objective and subjective markers for appetite (PYY and VAS) after intake of beta-glucan in healthy normal weight subjects. Furthermore, the changes in satiety may be mediated through colonic fermentation of beta-glucan, illustrated by the elevated fasting H2 excretion and fasting butyrate. Although more studies are needed to clarify the relationship between fibre, gut microbiota and satiety, these findings suggest anti-obesogenic potential of foods rich in beta-glucan.
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