Dietary fibre content and nutrient claims relative to the faecal bulking efficacy of breakfast cereals.

The correspondence between the dietary fibre contents of 28 breakfast cereals and their faecal bulking efficacies was measured and used to assess criterion values controlling nutrient claims for dietary fibre. A valid, standardised rat assay was used to measure faecal bulking efficacy as the content of wheat bran equivalents for faecal bulk (WBEfb) in the cereals. Regression analysis of WBEfb content against dietary fibre content allowed the adequacy of criterion fibre values for claims of 'source of fibre,' 'high in fibre' and 'very high in fibre' to be assessed relative to a daily reference requirement of 63 WBEfb, based on human data. Faecal bulking by breakfast cereals was much lower than implied by the dietary fibre claims associated with them. Many more were claimed to be 'high' or 'very high' in dietary fibre (n = 13) than were 'high' or 'very high' in faecal bulking efficacy (n = 4). Conversely, dietary fibre requirements per serving predicted from WBEfb requirements, as necessary to maintain adequate faecal bulk in the current Australian diet, were much higher (4.4 g) than the criterion fibre content (1.5 g) for the most modest claim, 'source of fibre'. After removing four high-bran cereals (>15% dietary fibre) from the analysis, a modest correlation of r = 0.62 between dietary fibre content and faecal bulk was obtained. It is concluded that, with respect to breakfast cereals, fibre values specified for nutrient claims are too low, dietary fibre content is not a reliable guide to faecal bulking efficacy and direct measures of faecal bulking capacity would be more useful than dietary fibre content in describing faecal bulking efficacy for evidence-based food choice.