The prevalence of chronic non communicable diseases (NCDs) is now reaching epidemic proportions in the developing countries. Indeed, India already has the highest number of diabetic patients in the world (50.8 million) and this is projected to increase to 87 million by the year 2030 (1). Indians have an increased susceptibility to diabetes which can, at least partly, be explained by genetic factors (2). However, genetic factors alone cannot explain the rapid rise in diabetes prevalence in urban India within a period of three decades (3). This strongly suggests the role of environmental factors.
Economic progress is inevitably associated with increasing urbanization. In addition to several features of urban life such as physical inactivity and unhealthy dietary practices, outdoor and indoor air pollution tend to increase the prevalence of diabetes and cardiovascular disease (CVD) also in urban India (4). The association between physical inactivity and obesity and the prevalence of diabetes has been established (5,6).
Cereals are staple diet in India, and carbohydrate consumption constitutes the bulk of the total calorie intake. Since 1980, the percentage of carbohydrate intake in Indian diets has remained relatively constant (55-65% of total calories), which is not much higher than that recommend by the WHO guidelines for the prevention of chronic diseases (7). However during this period, the prevalence of diabetes has increased from 8 per cent (1980) to 16 per cent (2006) in urban India, specifically in Chennai (3). We hypothesize that this could reflect changes in the quality of grains consumed today i.e., use of refined (e.g., highly polished rice) instead of the whole grains (less polished, hand pounded rice) consumed earlier.
Consumption of whole grains is beneficial while refined grains, which contains only the endosperm (starch) have an adverse effect on cardio-metabolic risk factors including glucose intolerance and diabetes (8). Also high carbohydrate diets raise plasma glucose, insulin, triglycerides and non-esterified fatty acids leading to insulin resistance (9). The quality of the carbohydrate i.e., glycaemic index (GI) and glycaemic load (GL) has also gained importance as a risk factor for development of chronic NCDs, particularly diabetes. Foods with higher GI and GL can cause rapid postprandial increase in blood glucose and insulin (10) and have been shown to increase the risk of type 2 diabetes and CVD in western (11,12) as well as in Asian populations, specifically in China (13) and India (14).
The traditional cereal-based Asian Indian diets were not only rich in dietary fibre, but also in other micro and phytonutrients. Use of unrefined carbohydrates, derived mainly from whole grains (unpolished / brown rice or whole wheat) could possibly explain the lower rates of CVD (15) and type 2 diabetes mellitus in India in the 1960s-70s (16). Unfortunately, for better shelf life, and consumer appeal, rice underwent a high degree of refining and milling (8-12%). As a result, the outer bran and germ portions of intact rice (i.e., brown rice) grains were removed to produce white rice that primarily consists of starchy endosperm (17). As the unrefined cereals were...