Wholegrain oat-based cereals have prebiotic potential and low glycaemic index

Population studies show a positive association between increased dietary intake of wholegrains and reduced risk of cardio-metabolic disorders. Consumption of wholegrain food has been associated with lower blood glucose and therefore may contribute to a low glycaemic-load diet. The ability to mediate a prebiotic modulation of gut microbiota has recently been suggested to have an inverse correlation to risk of cardio-metabolic disease. To date very little work has been carried out on the functionality of wholegrain breakfast cereals in terms of glycaemic response or impact on gut microbiota. Investigation into identifying wholegrain-based breakfast cereals demonstrating both low GI and prebiotic attributes was performed. After in vitro digestion, cereal samples were supplemented to pH-controlled anaerobic batch-cultures of the human faecal microbiota. Total bacteria populations increased significantly (P<0.05) in all treated cultures, and the fermentation of a wholegrain oat cluster cereal was associated with proliferation of the Bifidobacterium genus (P=0.02). Smaller, but significant increases in Bifidobacterium genus were observed for a further four oat-based cereals. Significant increases in Lactobacillus–Enterococcus group was observed for granola (P=0.01), 100% wholegrain aggregate (P=0.04) and 70% wholegrain loops (P=0.01). Cereals demonstrating prebiotic potential were selected for GI determination in twelve healthy subjects. The wholegrain oat aggregate cereal achieved the lowest GI value (40), three other cereals ranged between 44 and 74, with instant porridge resulting in a GI value similar to the standard glucose control. The current study suggests that wholegrain-oat-based breakfast cereals may be prebiotics and have the potential to have low GI.