Lokesh Khurana

CONTEXT: Prevalence of obesity and the metabolic syndrome is rapidly increasing in developing countries, leading to increased morbidity and mortality due to type 2 diabetes mellitus (T2DM) and cardiovascular disease. EVIDENCE ACQUISITION: Literature search was carried out using the terms obesity, insulin resistance, the metabolic syndrome, diabetes, dyslipidemia, nutrition, physical activity, and developing countries, from PubMed from 1966 to June 2008 and from web sites and published documents of the World Health Organization and Food and Agricultural Organization. EVIDENCE SYNTHESIS: With improvement in economic situation in developing countries, increasing prevalence of obesity and the metabolic syndrome is seen in adults and particularly in children. The main causes are increasing urbanization, nutrition transition, and reduced physical activity. Furthermore, aggressive community nutrition intervention programs for undernourished children may increase obesity. Some evidence suggests that widely prevalent perinatal undernutrition and childhood catch-up obesity may play a role in adult-onset metabolic syndrome and T2DM. The economic cost of obesity and related diseases in developing countries, having meager health budgets is enormous. CONCLUSIONS: To prevent increasing morbidity and mortality due to obesity-related T2DM and cardiovascular disease in developing countries, there is an urgent need to initiate large-scale community intervention programs focusing on increased physical activity and healthier food options, particularly for children. International health agencies and respective government should intensively focus on primordial and primary prevention programs for obesity and the metabolic syndrome in developing countries.

BACKGROUND: The prevalence of obesity and the metabolic syndrome is rapidly increasing in India and other south Asian countries, leading to increased morbidity and mortality due to type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD). METHODS: The literature search has been carried out using the key words "insulin resistance, the metabolic syndrome, cardiovascular risk, diabetes, obesity, Asian Indians, and South Asians" in the medical search engine Pubmed (National Library of Medicine, Bethesda, MD) from 1966 to September 2009. RESULTS: A high prevalence of the metabolic syndrome and associated cardiovascular risk factors has been observed not only in urban South Asian/Asian Indian adults and children but also in economically disadvantaged people residing in urban slums and rural areas. The main drivers are rapid nutrition, lifestyle, and socioeconomic transitions, consequent to increasing affluence, urbanization, mechanization, and rural-to-urban migration. Less investigated determinants of the metabolic syndrome include psychological stress in urban setting, genetic predisposition, adverse perinatal environment, and childhood "catch up" obesity. Data show atherogenic dyslipidemia, glucose intolerance, thrombotic tendency, subclinical inflammation, and endothelial dysfunction are higher in South Asians than Caucasians. Many of these manifestations are more severe and are seen at an early age (childhood) in South Asians than Caucasians. Metabolic syndrome and cardiovascular risk in South Asians is also heightened by their higher body fat, truncal subcutaneous fat, intra-abdominal fat, and ectopic fat deposition (liver fat, etc.). Further, cardiovascular risk cluster manifests at a lower level of adiposity and abdominal obesity. The cutoffs of body mass index and waist circumference for defining obesity and abdominal obesity, respectively, have been lowered and the definition of the metabolic syndrome has been revised for Asian Indians in a recent consensus statement, so that physicians could intervene early with lifestyle management. Data from a major intervention program conducted by us on urban adolescent schoolchildren in north India for prevention of obesity (the MARG project) has shown encouraging results, making it a model for any future intervention program in South Asians. CONCLUSIONS: Cardiometabolic risk is high in South Asians, starting at an early age. Increasing awareness of cluster of risk factors and how to prevent them should be emphasized in population-wide prevention strategies in South Asian countries, primarily focusing on children.

India is facing an "epidemic" of diet-related non-communicable diseases (DR-NCDs), along with widely prevalent undernutrition resulting in substantial socioeconomic burden. The aim of this paper is to review secular trends in food groups and nutrient intake, and implications for DR-NCDs in India so as to understand optimal choices for healthy diets for the prevention of DR-NCDs. The literature search was carried out in PubMed (National Library of Medicine, Bethesda, MD, USA) and Google Scholar search engines up to April 2011. A manual search for all other references, national and medical databases was also carried out. Nutrition transition over the past 30 years (1973-2004), has resulted in a 7% decrease in energy derived from carbohydrates and a 6% increase in energy derived from fats. A decreasing intake of coarse cereals, pulses, fruits and vegetables, an increasing intake of meat products and salt, coupled with declining levels of physical activity due to rapid urbanization have resulted in escalating levels of obesity, atherogenic dyslipidemia, subclinical inflammation, metabolic syndrome, type 2 diabetes mellitus, and coronary heart disease in Indians. Studies also suggest that adverse perinatal events due to maternal nutritional deprivation may cause low-birth weight infants, which, coupled with early childhood "catch-up growth", leads to obesity in early childhood, thus predisposing to NCDs later in life. In view of rapidly increasingly imbalanced diets, a multisectoral preventive approach is needed to provide balanced diets to pregnant women, children and adults, and to maintain a normal body weight from childhood onwards, to prevent the escalation of DR-NCDs in India.

Developing countries are undergoing rapid nutrition transition concurrent with increases in obesity, the metabolic syndrome, and type 2 diabetes mellitus (T2DM). From a healthy traditional high-fiber, low-fat, low-calorie diet, a shift is occurring toward increasing consumption of calorie-dense foods containing refined carbohydrates, fats, red meats, and low fiber. Data show an increase in the supply of animal fats and increased intake of saturated fatty acid (SFAs) (obtained from coconut oil, palm oil, and ghee [clarified butter]) in many developing countries, particularly in South Asia and South-East Asia. In some South Asian populations, particularly among vegetarians, intake of n-3 polyunsaturated fatty acids (PUFAs) (obtained from flaxseed, mustard, and canola oils) and long-chain (LC) n-3 PUFAs (obtained from fish and fish oils) is low. Further, the effect of supplementation of n-3 PUFAs on metabolic risk factors and insulin resistance, except for demonstrated benefit in terms of decreased triglycerides, needs further investigation among South Asians. Data also show that intake of monounsaturated fatty acids (MUFAs) ranged from 4.7% to 16.4%en in developing countries, and supplementing it from olive, canola, mustard, groundnut, and rice bran oils may reduce metabolic risk. In addition, in some developing countries, intake of n-6 PUFAs (obtained from sunflower, safflower, corn, soybean, and sesame oils) and trans-fatty acids (TFAs) is increasing. These data show imbalanced consumption of fats and oils in developing countries, which may have potentially deleterious metabolic and glycemic consequences, although more research is needed. In view of the rapid rise of T2DM in developing countries, more aggressive public health awareness programs coupled with governmental action and clear country-specific guidelines are required, so as to promote widespread use of healthy oils, thus curbing intake of SFAs and TFAs, and increasing intake of n-3 PUFAs and MUFAs. Such actions would contribute to decelerating further escalation of "epidemics" of obesity, the metabolic syndrome, and T2DM in developing countries.

A role of dietary nutrients in relation to insulin resistance has been suggested but conclusive evidence in human beings is lacking. Asian Indians and South Asians are prone to develop insulin resistance and the metabolic syndrome. In the present paper, data pertaining to nutrient intake, insulin resistance and cardiovascular risk factors in Asian Indians and South Asians have been reviewed. In these populations, several dietary imbalances have been reported: low intake of MUFA, n-3 PUFA and fibre, and high intake of fats, saturated fats, carbohydrates and trans-fatty acids (mostly related to the widespread use of Vanaspati, a hydrogenated oil). Some data suggest that these nutrient imbalances are associated with insulin resistance, dyslipidaemia and subclinical inflammation in South Asians. Specifically, in children and young individuals, a high intake of n-6 PUFA is correlated with fasting hyperinsulinaemia, and in adults, high-carbohydrate meal consumption was reported to cause hyperinsulinaemia, postprandial hyperglycaemia and hypertriacylglycerolaemia. Dietary supplementation with n-3 PUFA leads to an improved lipid profile but not insulin sensitivity. Inadequate maternal nutrition in pregnancy, low birth weight and childhood 'catch-up' obesity may be important for the development of the metabolic syndrome and diabetes. Even in rural populations, who usually consume traditional frugal diets, there is an increasing prevalence of cardiovascular risk factors and the metabolic syndrome due to changes in diets and lifestyle. Nationwide community intervention programmes aimed at creating awareness about the consequences of unhealthy food choices and replacing them by healthy food choices are urgently needed in urban and rural populations in India, other countries in South Asia and in migrant South Asians.