Lifestyle diseases predominate in Western nations while immunity related diseases of the upper respiratory tract predominate in developing nations. The associations between poverty and disease has been suggested to result from the amount of animal protein in the diet. High incomes in Western nations allow the incorporation of greater intakes of animal protein which optimises the immunity of the individuals, but at the same time supplies an overabundance of energy which may lead to insulin resistance, weight gain and lifestyle diseases. In developing countries the dependence on vegetables as a protein source provides insufficient essential amino acids for correct immune function, but is energy poor and so decreases the risk of developing lifestyle diseases. Detailed cross section analysis within developing countries reveals associations between body mass index (BMI) and socioeconomic status, something that may mirror the situation within Western nations.
For example, researchers1 surveyed a representative sample of 547,056 non-pregnant women, aged between 15 and 49 years in 37 low and middle income countries. When the data was analysed, positive associations were found between BMI and wealth in all 37 countries included in the survey. In earlier studies positive associations between BMI and wealth were found in 36 of the countries, suggesting that little change had occurred over time. Those in the wealthiest quintile had a BMI that was on average 3.0 units (kg/m2) higher than those in the poorest quintile. Comparison to data collected in earlier studies showed that this difference has previously been 2.32 units, suggesting that over time, the associations between wealth and BMI had not improved. Accelerations in weight gain was only higher amongst the poorer compared to the wealthier in 6 of the 37 countries studied.
The association between socioeconomic status and BMI has been reported many times, and this study supports previous findings. Increased wealth can lead to increases in disposable income, and this can expand the food choices available to the individuals. As countries and regions develop, the availability of Western processed foods can increase, allowing greater choice of energy rich foods. Increased wealth may therefore allow increased consumption of high energy dense foods that provide an over abundance of calories while at the same time being devoid of useful micronutrients. This scenario is suspected to contribute to the development of insulin resistance, which ultimately leads to metabolic syndrome, obesity and cardiovascular disease. The association between socioeconomic status and BMI is interesting because it suggests that genetic factors are less important in the development of obesity than previously thought. Identification of the environmental factors are therefore key in reversing the rise in obesity.
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