Effects of dietary medium-chain triglyceride on weight loss and insulin sensitivity in a group of moderately overweight free-living type 2 diabetic Chinese subjects

Abstract

Prior studies of medium-chain triglyceride (MCT) suggest that MCT might be a useful tool for body fat mass management in obese nondiabetic humans. We now report a pilot study that tests if MCT is beneficial for moderately overweight subjects with type 2 diabetes mellitus. The study was conducted in a group of 40 free-living subjects in an urban area of China. The subjects were randomized into 2 test groups, with one given MCT and the other corn oil as control for long-chain triglycerides (LCTs). The test oil (18 g/d) was administered as part of daily food intake for 90 days. All subjects completed the study with self-reported full compliance. Body weight, waist circumference (WC), and serum samples were analyzed on days 0, 45, and 90. The MCT group showed an across-time reduction in body weight and WC, an increase in serum C-peptide concentration, a reduction in homeostasis model assessment of insulin resistance, and a decrease in serum cholesterol concentration (P < .05, repeated measures). No significant across-time difference for the above parameters was detected for the LCT group. These changes were associated with an involuntary reduction in energy intake in the MCT group (P < .05, repeated measures). A between-group comparison also shows reduced body weight, WC, and homeostasis model assessment of insulin resistance in the MCT group compared with the LCT group at the end of the study. Collectively, our results suggest a link between moderate consumption of MCT and improved risk factors in moderately overweight humans in a low-cost, free-living setting.

Introduction

Dietary medium-chain triglyceride (MCT) has been shown to induce fat loss in animals and humans [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11] and reduces spontaneous energy intake [12], [13]. Many of these prior studies used high doses of MCT (80 g/d). Recent studies indicate that moderate doses of MCT (5-10 g/d) also increase postprandial energy expenditure and reduce body fat mass [3], [7], [14]. The effect of long-term dietary MCT on insulin sensitivity remains not well established and warrants testing. A second concern regarding the use of MCT is related to controversial reports of its effect on blood triglycerides and cholesterol [15], [16], [17], [18], [19], [3], [20]. Nevertheless, few studies, especially long-term studies, have been conducted using MCT in free-living human subjects [3], [7], [21]. In this work, we conduct a pilot study to test how MCT affects body weight (BW), insulin sensitivity, and serum lipid profile when administered at a moderate dosage to free-living moderately overweight (type 2) diabetic urban residents in China.