In an embodiment, the Streptococcus is Streptococcus thermophiles. In embodiment, the Escherichia is beneficial strain of Escherichia coli. In an embodiment, the Enterococcus is Enterociccus faecium. In an embodiment, the non-beneficial bacteria is a pathogenic strain of bacteria. In an embodiment, the non-beneficial bacteria is a pathogenic strain of bacteria selected from one or more of: Escherichia coli, Enterococcus, Helicobacter pylori, Clostridium, Vibrio cholerae, Bacteroides fragilis, Clostridium, Fusobacterium, Staphylococcus (e.g. pneumoniae), Legionella, Haemophilus, Pseudomonas, Prevotella, Salmonella, Campylobacter, and Shigella, Listeria. In an embodiment, non-beneficial bacteria is a pathogenic strain of Escherichia coli. In an embodiment, promoting gut health comprises modulating microbial diversity in the gastrointestinal tract of a subject. In an embodiment, modulating microbial diversity comprises increasing microbial diversity. This may occur, for example after a disturbance which reduces the microbial diversity of the gastrointestinal tract. The present invention has a number of specific forms. Additional embodiments of these forms are as discussed elsewhere in the specification. Preferred forms of the sugar compositions of the invention and the methods of their use include the following. A food grade sugar composition comprising sucrose, at least 16 mg to 800 mg GAE polyphenol / 100 g carbohydrate and about 0 to 0.3% w/w ash, wherein the sugar is prebiotic. A food grade sugar composition comprising sucrose, at least 16 mg to 800 mg GAE polyphenol / 100 g carbohydrate and about 0.05 to 0.3% w/w ash, wherein the sugar is prebiotic. A prebiotic food grade very low glycaemic sugar comprising at least about 90% w/w or 95% w/w sucrose. Alternatively, the present invention provides an edible very low glycaemic prebiotic sugar comprising at least about 98% w/w sucrose or 99% w/w sucrose. The sugars of this embodiment optionally comprise: (i) about 37 mg GAE polyphenols/1 00 g carbohydrates to about 80 mg GAE polyphenols/1 00 g carbohydrates, (ii) 0 to 1.5 % w/w reducing sugars, wherein the sugar is not more than 0.5% w/w fructose and not more than 1% w/w glucose, and/or (iii) a moisture content of 0.02% to 0.6%.