It is well known that poorer Americans are more likely to be obese or suffer from diabetes; there is a strong negative correlation between household income and both obesity and diabetes. This negative correlation, however, has only developed in the past 30 years, according to researchers in Tennessee and London. Since 1990, the rise of obesity and diabetes has been the fastest among the poorest U.S. regions, says Alexander Bentley of the University of Tennessee in the US. The timing also fits with the generations exposed to high fructose corn syrup in food and drinks, says Bentley, who is the lead author of a study in the journal Palgrave Communications, which is published by Springer Nature.
Experts describe the unprecedented rise in obesity in recent history as the most rapid change ever seen in human physiology. Only a century ago, obesity was a phenomenon almost unknown to citizens of the US and other developed countries.
In this study, Bentley and his colleagues analyzed the data made available by the Center of Disease Control and Prevention of obesity levels, leisure activities, income rates and incidence of diabetes. In most cases, this data was compiled for around 3000 US counties. The researchers also drew on data collected by the Food Access Research Atlas project. These documented person's access to vehicles and proximity to supermarkets and large grocery stores where they could buy affordable and nutritious food.
The analysis shows that in 1990, when population-scale obesity rates in the US were about a third of what they are today, there was no link between income and obesity or diabetes. By 2015, there was a strong likelihood that obesity or diabetes would be typical in lower income households. In states like Alabama, Mississippi and West Virginia, where the average household income was below 45,000 US dollars a year, 35 percent of people were obese. In more affluent states such as Colorado, Massachusetts or California, where households earned on average 65,000 US dollars a year, one in four citizens was obese.
"The data point to a developing trend that was not present in 1990. This negative correlation has evolved steadily over the last decades," explains Bentley. "By 2015, the situation was such that members of lower-income households had a much greater chance of suffering from obesity and diabetes."
Bentley and his colleagues speculate that oversupply and ready access to foods containing high fructose corn syrup may be driving obesity levels. In the past, people's diets contained very little sugar and no refined carbohydrates. Total sugar consumption in the American diet has risen gradually in the 20th century, from 12 per cent of US food energy in 1909 to 19 per cent by the year 2000.
"The timing is suggestive, with the generations of young Americans consuming high fructose corn syrup in foods predicting a similar increase in obesity as they became adults," Bentley notes.
High fructose corn syrup has been used in US foods since 1970. By the year 2000, every person in the US consumed on average about 27 kilograms of it per year, which is about half of their annual total sugar intake. Corn syrup is the main sweetener in soft drinks. In 2016, the average US household spent 7 percent and low-income households spent 9 per of their income on soft drinks.
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