Ideally, therefore, grain foods should be a source of energy that
is obtained without inducing an acute glycaemic response, and in a
sustained manner, and should make some contribution to nourishing
the colonic biota. Translated into terms of carbohydrate fractions
they should make a small contribution of rapidly digested
starch (RDS) or of rapidly digested starch plus soluble sugar (rapidly
available carbohydrate; RAC), a substantial proportion should
be slowly digested starch (SDS), and there should be a proportion
of starch (inaccessible digestible starch; IDS) that is undigested
in the time allowed by gut transit