The consumption of sorghum products and phloretin: implications for health and metabolic syndrome

Metabolic syndrome is a precursor to non-communicable diseases including type 2 diabetes and cardiovascular disease. Diet and lifestyle choices are major contributors to the development and progression of metabolic syndrome. Adding functional foods and functional compounds into the diet of those at risk of developing metabolic syndrome will improve metabolic status and, in the long term, minimise the incidence of the disease. This research aims to identify and quantify the impacts that sorghum and phloretin have on diet-induced metabolic syndrome. Methods: A 16 week rat model of diet-induced metabolic syndrome was used to determine responses to 5% whole red sorghum, 20% red sorghum flour, 20% black sorghum flour, 20% wet cake sorghum, or phloretin at 50mg/kg/day or 200mg/kg/day. Cardiovascular, physiological, and metabolic variables were measured. Studies were conducted to determine whether there were changes in intestinal permeability caused by alterations in colonic tight junction proteins which would lead to reduced serum LPS concentrations and TLR4-mediated inflammation which is known to contribute to metabolic syndrome. Results: Phloretin, a glucose transporter 2 inhibitor, normalised post-prandial blood glucose responses when consumed at 200mg/kg/day showing potential for the prediabetes aspect of metabolic syndrome. On the contrary this dose increased total plasma cholesterol which is considered to be a risk factor for increased cardiovascular events in metabolic syndrome. Whole sorghum reduced total cholesterol concentrations in a rat model of diet-induced metabolic syndrome, showing potential for reducing risk of cardiovascular events. Black and red sorghum flour showed remarkably few changes in a high fat-high carbohydrate diet, and the implications for metabolic syndrome are low. Improvements were observed in the liver and gastrointestinal tract, with reduced steatosis and a modest reduction in small intestinal permeability. Wet cake sorghum, the waste product of ethanol fermentation, showed the greatest changes of all the sorghum products with normalisation of post-prandial glucose, improved liver morphology, reduction in left ventricular collagen, and a modest reduction in small intestinal permeability. A number of changes were seen when adding sorghum into the control diet which did not develop metabolic syndrome. The outstanding change was a distinct increase in lean mass. There was little evidence to suggest that changes in the gastrointestinal tract were major contributors to improving metabolic syndrome through reducing metabolic endotoxaemia. Conclusions: Overall both phloretin and sorghum products show benefits to their consumption for attenuation of metabolic syndrome, which can be used as leverage for further clinical studies and for promotion of sorghum as a health food