GLOSSARY

Fermentable Fiber can be utilised and broken down to some extent by gut microorganisms. Extent and rate vary; fermentability differs from human enzymatic digestion and from demonstrated prebiotic status.

Large-intestinal microbes can convert some remaining carbohydrates into short-chain fatty acids and gases. This differs from direct glucose absorption and cannot be treated as equivalent rapid running fuel. Both the amount and rate of fermentation depend on the substrate's structure and the individual's microbial community.

Solubility, viscosity and fermentability are separate properties. Inulin can be soluble, low-viscosity and readily fermented; psyllium forms gels but is generally less fermented. Two ingredients described as soluble fibre therefore need not produce the same intestinal consistency, gas production or post-meal response.

Fermentation alone does not establish prebiotic status: selective utilisation by host microorganisms and a health benefit must be demonstrated. Increasing one bacterial group alone does not prove improved sport performance either. Evidence depends on ingredient, dose, studied population and actual outcome, rather than every fibre-containing product having the same effect.