Cereal fructan extracts alter intestinal fermentation to reduce adiposity and increase mineral retention compared to oligofructose.

ABSTRACT

PURPOSE: Intestinal fermentation of inulin-type fructans, including oligofructose, can modulate adiposity, improve energy regulation, and increase mineral absorption. We aimed to determine whether cereal fructans had greater effects on reducing adiposity and improving mineral absorption compared with oligofructose. METHODS: Thirty-two male Sprague-Dawley rats were randomly assigned to one of four dietary treatments that contained 0% fructan (control), or 5% fructan provided by oligofructose (OF), a barley grain fraction (BGF), or a wheat stem fraction (WSF). After 1 week on the diets, mineral absorption and retention was assessed. At 4 weeks, blood samples were collected for gut hormone analysis, adipose depots were removed and weighed, and caecal digesta was analyzed for pH and short-chain fatty acids (SCFA). RESULTS: The BGF and WSF, but not OF, had lower total visceral fat weights than the Control (p < 0.05). The fructan diets all lowered caecal pH and raised caecal digesta weight and total SCFA content, in comparison to the Control. Caecal propionate levels for OF were similar to the Control and higher for WSF (p < 0.05). Plasma peptide YY and glucagon-like peptide-1 levels were elevated for all fructan groups when compared to Control (p < 0.001) and gastric inhibitory peptide was lower for the WSF compared to the other groups (p < 0.05). The fructan diets improved calcium and magnesium retention, which was highest for WSF (p < 0.05). BGF and WSF in comparison to OF showed differential effects on fermentation, gut hormone levels, and adiposity. CONCLUSIONS: Cereal fructan sources have favorable metabolic effects that suggest greater improvements in energy regulation and mineral status to those reported for oligofructose.