The purified fiber used for the LGI breakfast and for 1 of the 2 HGI breakfasts was a preparation of nonfermentable purified cellulose from hazelnut shells (
ALSO, Zelbio, Italy), whereas, in the second HGI breakfast, the HGI - Lac meal, cellulose was replaced with 5 g of the undigestible and highly fermentable disaccharide
lactulose in crystalline form (INALCO, Milan, Italy).