Differential Effects of Chronic Ingestion of Refined Sugars versus Natural Sweeteners on Insulin Resistance and Hepatic Steatosis in a Rat Model of Diet-Induced Obesity.

Marion Valle,André Marette,Geneviève Pilon,Philippe St-Pierre

doi:10.3390/nu12082292

Abstract

While the detrimental effect of refined sugars on health has been the subject of many investigations, little is known about the long-term impact of natural sweeteners on metabolic disorders. In this study we compared the metabolic responses to chronic ingestion of refined sugars compared to various natural sweeteners in diet-induced obese rats. Wistar rats were fed a high-fat high-sucrose diet (HFHS) for 8 weeks and daily gavaged with a solution containing 1 g of total carbohydrates from refined sugar (sucrose or fructose) or six different natural sugar sources, followed by assessment of glucose homeostasis, hepatic lipid accumulation, and inflammation. While glucose tolerance was similar following treatments with refined and natural sugars, lowered glucose-induced hyperinsulinemia was observed with fructose. Consumption of fructose and all-natural sweeteners but not corn syrup were associated with lower insulin resistance as revealed by reduced fasting insulin and homeostatic model assessment of insulin resistance (HOMA-IR) compared to sucrose treatment of HFHS-fed rats. All-natural sweeteners and fructose induced similar liver lipid accumulation as sucrose. Nevertheless, maple syrup, molasses, agave syrup, and corn syrup as well as fructose further reduced hepatic IL-1β levels compared to sucrose treatment. We conclude that natural sweeteners and especially maple syrup, molasses, and agave syrup attenuate the development of insulin resistance and hepatic inflammation compared to sucrose in diet-induced obese rats, suggesting that consumption of those natural sweeteners is a less harmful alternative to sucrose in the context of obesity.

Highlights

Obesity is a worldwide epidemic associated with many metabolic disorders such as insulin resistance, increasing the risk of developing metabolic syndrome (MetS), non-alcoholic fatty liver disease (NAFLD), type 2 diabetes (T2D), and cardiovascular disease (CVD) [1,2]
While the vast majority of added sugars are consumed as sucrose, composed of equal parts of glucose and fructose, it is mainly the latter that is believed to represent the main culprit for the obesity and T2D epidemic
We evaluated the metabolic impact of the addition of only 4% of the total daily calories consumed as added sugar coming from natural sweeteners as compared to an equivalent amount of sucrose

Summary

Introduction

Obesity is a worldwide epidemic associated with many metabolic disorders such as insulin resistance, increasing the risk of developing metabolic syndrome (MetS), non-alcoholic fatty liver disease (NAFLD), type 2 diabetes (T2D), and cardiovascular disease (CVD) [1,2]. Obesity and associated metabolic disorders have arisen in parallel with the increased adoption of the Western lifestyle which is in part characterized by a diet rich in fat, refined carbohydrates, and generally low in fibers [3]. Among these dietary factors, added sugars—defined as sugars and syrups added to foods and beverages during preparation or processing—have been pointed out. Excessive consumption of added sugars (>10% of total energy intake) has been demonstrated to play a key role in the obesity pandemic [4,5]. Several public health organizations recommend limiting its intake [6].

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