The Epidemiological Transition in India

Recent evidence has emerged suggesting that developing countries are experiencing significant increases in non-communicable diseases (NCDs), especially among the poor and low-income populations (Shetty, 2002).  In developing countries about 40% of all deaths can be attributed to NCDs (Shetty, 2002).  Urban development and industrialization in these countries facilitate lifestyle and diet changes that can have a serious impact on populations that did not previously suffer from NCDs (Shetty, 2002).  India is no exception to these changes as it undergoes huge demographic transformations that vary across the states and regions.  An epidemiological transition is occurring as “complex changes in patterns of health, disease, and mortality” promote a shift from infectious diseases to non-communicable illnesses as the major driver for morbidity and mortality (Shetty, 2002).  India is currently undergoing this epidemiological transition and thus is dealing with both infectious disease at the poorest levels of society and chronic, non-communicable diseases in the upper levels of society. 

Some interesting studies have been done with migrant populations to understand the impacts that genetics and environment can have on an individual’s development of NCDs.  It has been shown that as migrants adopt the social and cultural lifestyles of their new environment, they develop disease patterns that resemble those of the local people (Shetty, 2002).  These environmental and behavioral changes may also expose pre-existing genetic disposition to certain NCDs that was not evident in the migrant’s previous lifestyle and location (Shetty, 2002).  Therefore the change in environment can have a direct impact on people who are intrinsically predisposed to have the illness.  For example, populations that have migrated to the United Kingdom from India have developed a high risk for coronary heart disease.  Despite the fact that the South Asian populations studied have plasma cholesterol levels below the national average in the UK and that their total and saturated fat intakes are no different from the national average, these people are at an increased risk for heart disease (Shetty, 2002).  This propensity to develop coronary heart disease may be due to a change in diet, lifestyle, or physical activity that occurred upon their migration to the UK (Shetty, 2002).  When ethnic populations have a disease-risk pattern that deviates from the indigenous population, it is likely that this variation is due to environmental aggravation of genetic predisposition (Shetty, 2002).  The increased risk of NCDs associated with migration is not just limited to international transitions, but may also be found in internal migration or areas undergoing urbanization (Shetty, 2002). 

Obesity and its related problems like high cholesterol are increasing in India due to the changing lifestyles and standards of living brought about by urbanization.  It is possible that malnourished children may be more at risk for obesity.  If a child undergoes several episodes of nutrient deprivation followed by rehabilitation, there may be a “discordance between linear growth and adipocyte development” that encourages the growth of fat cells at the expense of the child’s height, which is limited by the lack of nutrients (Shetty, 2002).  In addition childhood obesity is affected by decreased physical activity, especially in urban Indian cities where there is increased food intake along with an increase in sedentary lifestyles (Shetty, 2002).  Although adult obesity is less well studied, the Nutrition Foundation of India found that there were higher rates of obesity among the higher socio-economic classes and very low rates among the population living in urban slums (Shetty, 2002). 

The changing food consumption patterns in India are contributing to increasing prevalence of NCDs.  Although there has not been a significant increase in energy intake, there has been an increase in the amount of energy from fat that Indians are consuming (Shetty, 2002).  Between the years of 1975 and 1995, there was a decrease in the intake of cereal grains that was offset by the intake of milk products and animal fats (Shetty, 2002).  Traditionally pulses and legumes have been the source of protein in the Indian diet, but these animal proteins have superseded these foods (Shetty, 2002).

Chadha, Gopinath, and Shekhawat conducted a study to understand how the lifestyle, dietary, and physical activity patterns that accompany urbanization affected the prevalence of coronary heart disease in India (1997).  The study found that the prevalence of clinical coronary heart disease was 31.9 per 1,000 in urban areas compared to 5.9 per 1,000 in rural areas (Chadha, et al., 1997).  An examination of the risk factors for heart disease – hypertension, diabetes, obesity, family history, and smoking – shows that they follow the same pattern of high prevalence in urban areas (Chadha, et al., 1997). Sodium and alcohol consumption were also higher in urban than rural areas (Chadha, et al., 1997). 

The high rates of coronary heart disease risk factors in urban areas are most likely due to a sedentary lifestyle (Chadha, et al., 1997).  In contrast, rural men and women are more likely to be involved in the physical labor of agriculture (Chadha, et al., 1997).  A study cited by Chadha et al. found that urban populations were 2.5 times more likely to have coronary heart disease than rural populations (1997).  Chadha et al. also attribute the prevalence of coronary heart disease in urban populations to the considerable air pollution present in cities.  Pollutants like oxides of nitrogen, sulfur dioxide, and suspended particles are strong inducers of the buildup of fats and cholesterol in arteries (Chadha, et al. 1997).  This study of the increased prevalence of heart disease in urban areas is one example of the epidemiological transition occurring in India.  As more of the country urbanizes and populations change their lifestyles, there will be an increasing number of individuals suffering from chronic, non-communicable diseases, like heart disease.  

References:

Chadha, S.L., Gopinath, N., & Shekhawat, S. (1997). Urban-Rural Differences in the Prevalence of Coronary Heart Disease and its Risk Factors in Delhi. Bull. World Health Org. 76(1): 31-38. 

 

Shetty, P.S. (2002). Nutrition Transition in India. Public Health Nutrition 5(1A): 175-182.