This blog is intended to go along with Population: An Introduction to Concepts and Issues, by John R. Weeks, published by Cengage Learning. The latest edition is the 13th (it will be out in January 2020), but this blog is meant to complement any edition of the book by showing the way in which demographic issues are regularly in the news.

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Saturday, March 7, 2015

Global Dietary Patterns--Generally Getting Worse Not Better

Historical data suggest that improving diets--especially more calories--helped raise life expectancy in Europe up to about 40 years at the beginning of the 19th century. Public health improvements such as clean water, sewerage, validation of the germ theory, and vaccinations, helped push life expectancy up into the 60s. It takes medical advances to get much beyond the 60s and we are headed that way globally, except for the fact that diets are now holding us back. This idea was first put forward by Barry Popkin at UNC Chapel Hill and his colleagues as the natural consequence of the nutrition transition. Finding data to track trends has not been easy, however, which is why the paper just published in The Lancet Global Health is so informative (this is open access so it is available to everyone). A group of researchers associated with the Global Burden of Diseases Nutrition and Chronic Diseases Expert Group tracked down every national level survey they could find that included dietary intake data collected at the individual levels. This way they could evaluate differences not only by country, but also by age and sex. The results suggested that age and sex were less important than overall national differences, based especially on overall levels of income.
Nations with higher incomes had larger improvements in diet patterns based on healthy items than did nations with lower incomes; for example, by 2·5 points (95% UI 0·5–4·6) comparing high-income to low-income countries. By contrast, middle-income nations showed the largest worsening in diet patterns based on unhealthy items: compared with high-income nations, greater worsening by 2·5 points (95% UI 0·5–4·5) and by and 2·8 points (95% UI 0·9–4·8) was noted in upper-middle nations and lower-middle income nations, respectively. Although most world regions showed modest improvements in dietary patterns between 1990 and 2010 on the basis of more healthy items, such improvements were generally not noted in the poorest regions, including in sub-Saharan Africa and the Andean states of Latin America. Conversely, most regions of the world showed substantial declines in diet quality based on increased consumption of unhealthy items. The exceptions included many of the wealthiest regions including the USA and Canada, western Europe, Australia, and New Zealand, where consumption of these unhealthy items modestly decreased. Of note, for these world regions and nations, this improvement was superimposed on a poor starting score in 1990 (appendix pp 47–49 figure S24). Thus, despite some improvement by 2010, dietary scores for unhealthy items in wealthy countries remained among the worst in the world.
The map below shows the global pattern when good and bad dietary elements are balanced against one another. The best diets at the moment are actually in the poorer countries that have not yet moved into the income categories where they can afford the less healthy, but obviously desirable, diets. We have to hope that we can alter that trajectory and keep them on better diets even as incomes improve.

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