The ADA change probably has something to do with perceived fibre content. The idea of using fibre to help diabetics is based on the work of an English researcher called Dr David Jenkins many years ago now. Jenkins reported that guar gum added to bread and consumed with a meal could reduce postprandial blood sugar rises by up to 36 percent. Subsequently researchers have had variable results, to say the least, reproducing his experiment.
Jenkins additionally claimed that the continued use of guar gum resulted in a reduction of serum cholesterol levels. He claimed that cholesterol released into the intestines could be prevented from reabsorption by binding to the ‘fibre’. Subsequent research has given variable results, but it appears the it is soluble fibre found in beans and guar gum that make any kind of difference. Somehow fibre came to mean all fibre, not just the soluble variety. Grains do not contain soluble fibre.
Believe it or not Atkins was one of the biggest liars about the glycemic nature of some its food products.