Low carbohydrate and higher fibre diets independently alleviate type 2 diabetes and combining these two dietary approaches is most likely to be the most effective strategy in treatment and prevention of type 2 diabetes.
Outcome studies have documented improvement and remission of type 2 diabetes with carbohydrate restriction. Protection from diabetes has also been documented with increased dietary fibre. Nevertheless, important discoveries regarding the links between fibre, microbiota diversity, short chain fatty acids, intestinal barrier permeability, inflammation, metabolic homeostasis and appetite are widely underappreciated.
Cheap industrially produced foods based on high glycemic starches and sugars make up more than 50% of average food consumption and this is a major contributor to pre-diabetes and diabetes estimated to affect half of Americans. The increasing ratio of carbohydrates to fibre over the 20th century and best explains the increase in diabetes over the last 40 years.
Protective effects of fibre go way beyond the simple concept of bowel regularity: it is a powerful antidote to diabetes and many other diseases. Levels of short chain fatty acids (SCFAs) increase proportionately with fermentation of fibre by beneficial gut bacteria, mainly acetate, propionate and butyrate are essential nutrients for intestinal cells particularly butyrate which provides colonic epithelial cells their main energy source as well as cell signaling effects that improve the integrity, size and function of the whole hind gut increasing numbers of incretin producing L cells. Beneficial effects of SCFA are mediated through 2 types of free fatty acid receptors present in cells widely distributed in the body such as CNS, immune cells, fat cells, and insulin producing pancreatic islet cells and intestinal L cells which increase production of incretin hormones GLP1 and PYY on stimulation by SCFA. GLP1 and PYY suppress appetite and voluntary food intake (Spreckley, 2015). GLP1 has multiple beneficial actions across the body but particularly regulating glucose metabolism, pancreatic beta cell function and appetite suppression. GLP1 agonist drugs are widely used for the treatment of diabetes and obesity but endogenously produced GLP1 is largely responsible for the remarkable cure rate of type2 diabetes with gastric bypass surgery. Both GLP and SCFAs are involved with preserving intestinal permeability barrier function. Butyrate and propionate have powerful anti-inflammatory effects and may reduce autoimmune diseases, allergies and promote oral tolerance of potential food allergens. Furthermore, the ‘Leaky Gut’ hypothesis may be a triggering event in inflammatory conditions and autoimmune diseases such as colitis, arthritis, asthma, celiac disease and type 1 diabetes as well as a factor in age-related diseases that are thought to be increased by systemic inflammation such as heart attacks, strokes, cancer, and dementia.