Convergence of obesity and high glycemic diet on compounding diabetes and cardiovascular risks in modernizing China: An emerging public health dilemma

Globalization and Health BioMed Central Review Open Access Convergence of obesity and high glycemic diet on compounding diabetes and cardiovascular risks in modernizing China: An emerging public health dilemma Eric L Ding* and Vasanti S Malik Address: Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts, USA Email: Eric L Ding* - ; Vasanti S Malik - * Corresponding author Published: 26 February 2008 Globalization and Health 2008, 4:4 doi:10.1186/1744-8603-4-4 Received: 3 August 2007 Accepted: 26 February 2008 This article is available from: http://www.globalizationandhealth.com/content/4/1/4 © 2008 Ding and Malik; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract As China is undergoing dramatic development, it is also experiencing major societal changes, including an emerging obesity epidemic, with the prevalence of overweight and obesity doubling in the past decade. However, the implications of a high glycemic index (GI) and glycemic load (GL) traditional Chinese diet are adversely changing in modern times, as a high-glycemic diet is becoming a greater contributor to diabetes and cardiovascular risks in a population with rising obesity and decreasing physical activity. Specifically, a high GI diet adversely impacts metabolism and appetite control regulation, and notably confers substantially greater risk of weight gain, type 2 diabetes, cardiovascular disease, and certain cancers among overweight and obese individuals (P<0.05 for all); leading to an emerging vicious cycle of compounding adverse health risks. Notably, while no elevated risk of cardiovascular disease and type 2 diabetes were observed with higher GL intake among normal weight individuals, among overweight individuals, higher GL was strongly associated with higher risk of coronary heart disease (RR=2.00, 95%CI: 1.31-2.96), stroke (RR=2.13, 1.283.53), and type 2 diabetes (RR=1.52, 1.22-1.89 among Chinese). Additionally, the influx of Westerndiets rich in saturated fats and high-glycemic sugar-sweetened beverages also threaten the health of the population. This review highlights the emerging adverse convergence of a high-glycemic Asian diet with a Chinese society experiencing an emerging obesity epidemic, and the important implications of these combined factors on compounding cardiometabolic risks. Potential policy directions in China are also discussed. Introduction Cardiovascular disease, diabetes, and cancer are not only leading causes of death in Western society, but have also recently become leading contributors of overall mortality in the People's Republic of China [1,2], where this is also a recent obesity epidemic [3-5]. From a nationally representative study, it is estimated that a large proportion of chronic disease mortality in China is attributable to physical inactivity, obesity, and obesity-related metabolic con- ditions [2]. Further exacerbating this problem is the convergence of a modernizing China and increasing obesity with a traditional high-glycemic Chinese diet, which together acts in tandem in increasing the risk of metabolic and cardiovascular diseases. Lifestyle factors, such as nutrition, are recognized to play important roles in metabolic conditions such as obesity, diabetes, hypercholesterolemia, and cardiovascular disPage 1 of 8 (page number not for citation purposes) Globalization and Health 2008, 4:4 eases [6-15], as well as risk of cancer [11,16-22]. Recently, the quality of dietary carbohydrates has gained wide recognition as an important risk factor for disease. Wholegrain carbohydrates are regarded as more favorable while refined carbohydrates are regarded as more adverse for cardiovascular risk [9,15,23], not only due to their cereal fiber content but also for their glycemic index properties. The glycemic index (GI) and glycemic load (GL = GI * grams of carbohydrate) reflect the nature of carbohydrates in causing rapid postprandial increase in blood glucose and insulin levels [24,25], which have been rather consistently recognized to contribute to adversely impact a variety of metabolic risk factors. Notably a high GI/GL diet has been positively associated in multiple studies with weight gain and obesity in both animals [26] and humans [25,27,28], as well as higher levels of serum triglycerides, LDL cholesterol levels, and serum coagulation factors [25,29]. Increased insulin, as result of a high GI/GL diet, may also stimulate ovarian secretion of androgens, which has adverse metabolic consequences on risk of type 2 diabetes in women [30,31]. All thes mechanisms consequently leads to a high GI/GL diet being repeatedly shown to adversely effect glycemic control in individuals with diabetes [32], as well as associated with greater risk of developing type 2 diabetes [33-36], coronary heart disease [9,37-39] and stroke [40,41] in prospective studies. Thus, an important risk factor relevant to Chinese society is the quality of dietary carbohydrate consumed as traditionally the Chinese diet consists of a variety of high-glycemic rice products as the staple grain, contributing as the primary source of caloric intake. While a high-glycemic Chinese diet did not formerly contribute to disease in an active and lean population, such a diet has important implications in a modernizing Chinese society characterized by increasing rates of adiposity, due an inherent biologic interaction in which high GI diet elicits significantly greater adverse effects in an overweight and obese population. This review highlights the emerging adverse convergence of a high-GI Asian diet with a Chinese society experiencing an emerging obesity epidemic, and the important implications of these combined factors on a series of compounding cardiometabolic risks and obesitydependent conditions. Discussion Obesity in China Like the rest of the world, China is experiencing an increased epidemic of obesity [3-5]. An estimated onequarter of the Chinese population is overweight or obese [5,42]. A national survey in 2002 found that the prevalence of Chinese adult overweight and obesity has nearly doubled in the last 10 years [3] to 23% [5], with another national study estimating the prevalence at 27–31% in Chinese adults [43]. More dramatically, childhood over- http://www.globalizationandhealth.com/content/4/1/4 weight and obesity has substantially increased in China [3,44], from 1–2% in 1985 to 7–13% prevalence in larger Chinese cities in 2002 [3]. Additionally, in 2000 a study of adolescent students in 6 large Chinese cities found that the prevalence of childhood overweight and obesity has dramatically increased to over 14% for girls and 25% for boys [45]. A recent nationally-representative study in China comparing p (...truncated)