We propose to use Hi-maize 260 and polydextrose (PD) as our model resistant starch (RS) intervention agents. RS describes the fraction of dietary starch which is not digested in the small bowel and which flows to the colon where it is a substrate for bacterial fermentation. (Asp, 1996) PD is produced by the bulk melt polycondensation of glucose and sorbitol to produce an oligosaccharide with a mean degree of polymerisation of 12 which is resistant to mammalian GI enzymes and, like other RSs, is a substrate for bacterial fermentation. (Auerbach, 2007) Both Hi-maize and PD are fermented (to a greater or lesser extent) producing short-chain fatty acids (SCFA) including butyrate. (Asp, 1996) Butyrate has beneficial effects on gut physiology and immune function including anti-inflammatory effects. (Wächtershäuser, 2000; Dronamraju, 2009)