Relatively few prebiotics substances are known and the identification of a new prebiotic is significant. In addition, the sugar compositions of the invention have been found to have reduced sugar bioavailability. This is of particular interest as the sugars are suitable for substitution for traditional white sugar, lowering the risk of diabetes upon consumption. Further, when testing the bioavailability of the sugar compositions of the invention, the sugar compositions of the invention were found to have prebiotic effect. The negative impact of white sugar on the gastro-intestinal microbiome means it is very surprising that a sugar, which is still largely sucrose, can have a positive impact on the gastro- intestinal microbiome. This is of particular value where the sugar remains palatable and/or substitutable for traditional white sugar. Prebiotic composition with two or more of hemicellulose, cellulose and lignin (eg bagasse) In a first aspect, the present invention provides a method of increasing the quantity of probiotics in the colon of a mammal comprising consumption by the mammal of at least 3 g of a composition comprising two or more of hemicellulose, cellulose and lignin (such as sugar cane bagasse). Optionally, the probiotic bacteria increased is one or more of lactic acid bacteria, Bifidobacteria, Bacteroidetes, Baciullus, Streptococcus, Escherichia, Enterococcus, Anaeropstipes, Bacillus, Odoribacter, Victivallis (phylum Lentisphaerae) and unclassified Lentisphaerae, unclassified Marinilabiaceae and Anaerophaga (family Marinilabiaceae), Anaerophaga, Cerasicoccus, Roseburia, and/or Shigella species. In an alternative first aspect, the present invention provides a method of increasing the quantity of probiotics in the colon of a mammal comprising consumption by the mammal of at least 3 g of a bagasse. Sugar cane, sugar beet and sorghum stalk bagasse is suitable. In preferred embodiments the bagasse is sugar cane bagasse. Ammonia is a metabolite produced by the microbial fermentation of nitrogen containing molecules (such as protein, peptides, peptone and urea). Optionally, the increase in probiotic bacteria is measured by increase in ammonia. Optionally, the increase in ammonia in the colon following consumption of the composition is significant when compared to the ammonia following consumption of cellulose at 32, 56 or 80 hours. It is difficult to test the increase in bacteria and/or ammonia in the colon in vivo. Instead, testing is conducted using in vitro models such as the model used in Example 8.