Optionally, the composition further includes ash. In some embodiments of the first and alternate first aspect of the invention, the composition or bagasse is about 20-25% w/w hemicellulose, about 45-55% w/w cellulose and about 18-24% lignin. Optionally, the composition or bagasse is also about 1-4% ash. Optionally, at least 3.5 g or at least 7 g of the composition or bagasse is consumed. Optionally, the Rosebuira was increased over 3-fold (eg about 3.5-fold) 80 hours following consumption of 3.5 g of the composition. Optonally, the Roseburia was increased over 7-fold (eg about 7.5-fold) 80 hours following consumption of 7 g of the composition. In some embodiments, the composition of the invention is sugar cane fibre or sugar beet fibre. Optionally, the composition further comprises probiotics. In some embodiments, the method is for the treatment of dysbiosis or diarrhoea (infectious, travellers’or antibiotic-associated diarrhoea). Alternatively, the method is for prevention of colon cancer. In another alternative first aspect, the present invention provides a method comprising: - selecting a mammal in need of treatment for dysbiosis or diarrhoea (infectious, travellers’or antibiotic-associated diarrhoea), or weight management; and - administering at least 3 g of bagasse or composition comprising two or more of hemicellulose, cellulose and lignin to that mammal; wherein the method increases the quantity of probiotic bacteria in the colon of the patient. Optionally, 7 g bagasse or composition is administered. Optionally, administration occurs at least once a day for 7 to 30 days. The bagasse or composition may be in the form of a capsule (eg similar to probiotic capsules) or in the form of a food. In a second aspect, the present invention provides a method of weight management for a mammal comprising consuming at least 3 g per day of a composition comprising two or more of hemicellulose, cellulose and lignin (such as sugar cane bagasse). The composition used in the second aspect of the invention is optionally as described in the first aspect of the invention.