• Polysaccharides, principally fructo-oligosaccharide made up of fructose units and galacto-oligosaccharide made from galactose units, which resist digestion in the stomach and small intestine and reach the colon intact. They are then selectively metabolized by the so-called beneficial bacteria, bifido bacteria and lacto bacilli. Now being added to foods as a selling point although they are of no use without the presence of these bacteria and increase flatulence.