THE EFFECTS OF OAT β-GLUCAN CONSUMPTION ON THE ENERGY INTAKES OF HEALTHY INDIVIDUALS

Abstract

Overweight and obesity are disease states of a huge public health concern, therefore strategies to impede or reverse the current detrimental overweight and obesity epidemic are of fundamental importance. It is important to understand dietary factors that affect appetite and food intake both in short- and long-term, as energy intake can lead to positive energy balance. Following the discovery of the bioactivity of cereal soluble fibre, (1→3,1→4)-β-ᴅ-glucan, there has been extensive attention among researchers, the food industry and consumers since the 1980s. Several authorities, including the U.S Food and Drug Administration (FDA) and European Food and Safety Administration (EFSA) have acknowledged the cardiovascular (CV) health benefits of β-glucan consumption by broadcasting ratified health claims based on robust scientific evidence. Yet despite evidence to suggest that cereal β-glucan can beneficially impact on appetite, the underpinning mechanisms whereby β-glucan influences energy intakes remain elusive. Given that there is no ratified health claim for β-glucan consumption and satiety, the aim of this work was to investigate the impact of oat β-glucan consumption on energy intakes of healthy individuals over both short- and medium-term. β-glucan enrichment of a semi-solid, viscous breakfast (4 g oat β-glucan) had no effect on subsequent eating (p=0.388) in 33 normal-weight subjects (22 female/11 male, mean age (y): 27.0 ± 1.0, BMI (kg/m2): 23.5 ± 0.4), however there was a significant increase in subjective feelings of satiety (p=0.034) and fullness (p=0.048). Additionally, attenuation of glucose (p<0.001) and insulin (p=0.001) were reported alongside a decreased response in GLP-1 after 90 minutes (p=0.021) in study A. A novel β-glucan-enriched oatcake snack (4.46 g β-glucan) had no effect on daily energy intakes of healthy overweight and obese subjects (11 female/2 male, mean age (y): 34 ± 9, BMI (kg/m2): 29.8 ± 4.4) when consumed daily for six weeks when compared to a control snack group during week 3 (p=0.39) or week 6 (p=0.58) of the study. Moreover, there were no significant improvements in markers of abdominal obesity, waist circumference (WC, p=0.67), sagittal abdominal diameter (SAD, p=0.38), BMI (p=0.99) or body fat percentage (BF%, p=0.54) between groups in study B following 6 weeks of β-glucan-enriched snack consumption. To conclude, evidence reported in this thesis supports evidence that oat β-glucan consumption does not influence short- or medium-term energy intakes in healthy individuals, however, in the short term β-glucan does increase subjective ratings of appetite and attenuates postprandial glucose, insulin and GLP-1 responses. Keywords: oat β-glucan, energy intake, appetite, GLP-1, body composition