Oral Presentation Australian Diabetes Society and the Australian Diabetes Educators Association Annual Scientific Meeting 2017

Impact of dietary carbohydrate composition on metabolic benefits of low protein-high carbohydrate diets.      (#103)

Jibran A Wali 1 2 , Tamara Pulpitel 1 , Melkam Kebede 1 , Timothy Dodgson 1 , Gabriela Pinget 1 , Belinda Yau 1 , Ian Matthews 1 , Devin Wahl 1 , Glen Lockwood 2 , Samantha M Solon-Biet 1 , Gregory J Cooney 1 , Victoria C Cogger 1 2 , David G Le Couteur 1 2 , Stephen J Simpson 1
  1. Charles Perkins Centre, The University of Sydney, Sydney, NSW, Australia
  2. Biogerontology Laboratory, Ageing and Alzheimer’s Institute and ANZAC Research Institute, Concord Hospital., Sydney, NSW, Australia

Nutrition is the major modifiable factor that influences health-span. Recent research using Geometric Framework (GF), a state-space nutritional modelling method, showed that ‘low protein-high carbohydrate’ (LPHC) diets generate the best cardio-metabolic health and lifespan. This seems at odds with advice to reduce intake of simple carbohydrates because there is evidence that they promote metabolic disease. Therefore, we aimed to evaluate which types of carbohydrate contribute to the benefits of LPHC diets.

Male C57BL/6 mice (n=300) were fed ad-libitum one of 15 isocaloric LPHC diets for 18 weeks composed of differing percentages of low protein (5-15%), high carbohydrate (65-75% with five different sucrose-starch ratios), and 20% fat. This array allows examination of the impact of each individual food component (protein, sucrose and starch) and their interactions using GF methodology. Metabolic health was assessed after 5-6 and 13-14 weeks on diets.

GF analysis showed that mouse weights and adiposity were markedly affected by protein intake and peaked on a combination of increased protein-high starch consumption, but high sucrose ingestion reduced fat mass. In contrast, energy intake increased on lower protein-high starch diets and declined with an increase in dietary protein and sucrose content. Similarly, lower protein consumption increased energy expenditure and circulating FGF-21, and lower protein-high carbohydrate ingestion yielded peak FGF-21 levels. Glucose tolerance and insulin concentrations were adversely affected by protein intake, but surprisingly, moderate sucrose intake did not impair glucose homeostasis, while extreme consumption paradoxically improved insulin sensitivity due at least in part to decreased food intake. Triglyceride levels increased while liver fat decreased with increasing protein consumption, but increased sucrose intake did not induce dyslipidaemia or hepatic steatosis.

Overall, in the setting of LPHC diets, protein intake is the major determinant of the metabolic phenotype, while compared to starch, very high sucrose intake paradoxically improves parameters of metabolic health.