In their recent paper in PLoS Medicine, Ezzati et al compared body mass index (BMI), cholesterol and blood pressure with national income, share of income spent on food and degree of urbanization across more than a hundred countries. The goal is to explore the link between development and the appearance of cardiovascular diseases.
Some observations from the paper:
Average BMI and cholesterol increase, then level off and finally decline with increasing national income except in the United States. BMI declines more rapidly at higher incomes for females than males again, except in the United States. I've cobbled together this figure from a much larger one to illustrate this point:
The first graph is men, the second women. Notice how at higher GDPs BMI in women drops off more rapidly than in men, but in both genders mean BMI is equal (and high) in the United States. As anyone who's traveled could tell you, only in the States are we both wealthy and enormous.
There's a strong positive correlation between urban living, BMI and cholesterol. Thus, as populations shift to urban living, they gain weight and have increased cholesterol. Indonesia and Nigeria buck this trend, having substantial urbanization without the same degree of increase in BMI and cholesterol.
There was no good correlation between anything and high blood pressure. The authors attribute this to regional differences in diet, which can directly influence blood pressure independent of other cardiovascular concerns.
The final paragraph:
The division between the diseases of poverty and affluence has provided a convenient tool for targeting policies towards risks such as undernutrition that affect the poor [56]. Demographic and technological change, however, are increasingly modifying the income patterns of cardiovascular risk factors and shifting their burden to the developing world. As a result, low-income and middle-income countries increasingly face the double burden of infectious disease and cardiovascular risk factors. Unless the research and intervention needs described earlier are pursued, this will create a world in which all major diseases are the diseases of the poor.
Both the authors of this paper and Thomas E. Novotny, in his review, infer from these results that we need to intervene with developing nations before they climb the slope of increasing BMI and related issues. A salient question, though, is whether we expect the developing world to act like us and just keeping getting larger, or act like the rest of the developed world and come back down to a healthier steady state.
An added thought: I'd really like to see a longitudinal version of this study.
Ported comments:
(Anonymous)
2005-06-14 11:17 pm UTC (link) DeleteFreezeScreen Select
Could you clarify the bit on "urban living"....? Where is the line between shifting to "urban living" and suburban living? Smart Growth members (and the new urbanists) constantly point out the better health and lower weight of individuals who live in cities or pedestrian communities, as opposed to suburbs. What are the suburbanization rates (or housing density/pedestrian access rates) for the countries included in the study? -d
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[info]parakkum
2005-06-15 12:11 am UTC (link) DeleteFreezeScreen Select
They make no distinction in the paper between urban and suburban. The sole distinction is between urban and rural, as defined in a UN report -- World Population Prospects: the 1998 Revision. I could only find the 2002 and 2000 revisions online. The 2002 didn't appear to address this issue.
Here's what the authors have to say about the rural/urban distinction as it applies to their study:
The proportion of the population living in urban areas is a proxy indicator of a number of environmental and lifestyle variables, such as physical activity in occupational and transportation domains, and of access to specific food types. For example, people living in rural areas often have higher levels of physical activity, reflecting their agricultural occupations and the need to walk longer distances for day-to-day activities [15]. Similarly, rural and urban populations may have differential access to various food types, possibly with seasonal variations. Urban populations are also likely to have higher access to screening and treatment for risks such as high blood pressure and cholesterol.
The cite there [15] was this paper that I have not read:
Levine JA, Weisell R, Chevassus S, Martinez CD, Burlingame B, et al. (2001) The work burden of women. Science 294: 812.