Abstract
Background: The removal of fibre from wholegrain foods may have contributed to the diabetes epidemic. Functional fibres may be an effective alternative to intrinsic food fibres for helping individuals add more fibre back into their diet. However, inconsistent results combined with underpowered studies in this field, in particular for insoluble and mixed functional fibres, have made its association with glycaemia and hence potential health benefits unclear.
Objective: To determine the effects of a predominately insoluble functional fibre, fruit fibre (FF), and a mixed functional fibre containing different soluble and insoluble polysaccharides, FibreMaxTM (FM), on postprandial glycaemia.
Methods: In a double-blinded design consisting of a pair of randomised crossover trials, 80 participants consumed a control bread, and either a bread enriched with 10g of FF (n=37), or a bread enriched with 10g of FM (n=43). Capillary blood glucose was measured at 0, 30, 45, 60, 90, and 120 minutes.
Results: The consumption of FF bread reduced postprandial glucose incremental area under the curve (IAUC) by 35% (95% CI 13, 51), P=0.004. The FM bread reduced postprandial glucose IAUC by 43% (95% CI 17, 61), P=0.004. Compared to their controls, both fibre-enriched breads significantly decreased incremental peak blood glucose, which appeared to occur at 45 minutes, by 0.5mmol/l (95% CI 0.2, 0.9), P=0.004 for FF and 0.9mmol/l (95% CI 0.5, 1.3), P≤0.001 for FM.
Conclusion: If the glycaemic results are more generalisable to a population with impaired glucose tolerance, then enriching bread with supplemental fibre may be a useful strategy to help manage blood glucose.