Research links NAFTA to Canada’s increasing obesity and diabetes rates

By Douglas Yu

- Last updated on GMT

Tariff reductions in NAFTA coincided with a 41.6 kcal per capita daily increase in the supply of caloric sweeteners including HFCS in Canada.  Photo: ©iStock/Darwel
Tariff reductions in NAFTA coincided with a 41.6 kcal per capita daily increase in the supply of caloric sweeteners including HFCS in Canada. Photo: ©iStock/Darwel

Related tags North american free trade agreement International trade Corn syrup

Research published on Canadian Medical Association Journal suggests the North American Free Trade Agreement (NAFTA) is associated with a significant rise in high-fructose corn syrup (HFCS) consumption in Canada. 

HFCS is a form of sugar that has been linked to the development of noncommunicable diseases and health risk factors, including obesity and diabetes, and it is often used in confectionery and bakery products such as biscuits, main author of the research, Pepita Barlow said.

Barlow is a Ph.D. student at the University of Oxford, and has a background in sociology and economics.

Removing HFCS-related tariffs

The research pointed out when NAFTA superseded an earlier trade agreement between the US and Canada, CUSFTA (the Canada-US Free Trade Agreement), in 1994, it removed tariffs on food and beverage syrups containing HFCS, making it cheaper for Canadian food manufacturers to use the commodity imported from the US.

Source: Canadian Medical Association Journal

“The daily per capita supply of caloric sweeteners including HFCS rose from 21.2 kcal in the pre-NAFTA period to 62.9 kcal post-NAFTA,”​ said researchers. “The rise in caloric sweeteners persisted for each year that tariffs were reduced, stopping after the final reduction in 1998.”

“The rise in HFCS consumption was correlated with a large rise in obesity rates, from 5.6% in 1985 to 14.8% in 1998,”​ researchers added. “Rates of obesity among Canadians now rank among the highest of advanced industrialized nations that do not have trade agreements with the US.”

Additionally, the period after NAFTA also corresponded with a rise in the prevalence of diabetes from 3.3% (1998/1999) to 5.6% (2008/2009), according to the research.

Research methods

Pepita said the research team used a “synthetic control”​ model to estimate the HFCS supply in Canada against a control group, including specific countries and a weighted combination of comparison control nations.

Those control countries did not enter a US free trade agreement during the study period, she mentioned.

Results showed that the trend in supply of sweetener syrups was very similar in Canada and its control before NAFTA, but after the trade agreement went took effect, supply of caloric sweeteners was 43.7 kcal/capita daily higher in Canada compared with the control in the post-NAFTA period.

Researchers said no ethics approval was required for the study, as they used publicly available, pre-anonymized data from the Food and Agriculture Organization of the United Nations Statistics Office.

However, they said their analysis has several limitations. For example, the study only analyzed changes in one specific product category in a developed country, and the corn and soft drink industries may distort evidence of the harms from HFCS.

Implications for post-Brexit UK

NAFTA has been held up as a blueprint for future free trade agreements including a potential new deal between the US and UK following its decision to leave the European Union, the research said.

“Our analysis of the effects NAFTA raises concern that new trade deals could harm population health should lower tariffs lead to increased supply and potential consumption of unhealthy food items,”​ Pepita said.

“Potential harms may be counteracted partially by targeted public health policies,”​ she said.


CMAJ July 4, 2017 vol. 189 no. 26 
doi: 10.1503/cmaj. 161152
'Impact of the North American Free Trade Agreement on high-fructose corn syrup supply in Canada: a natural experiment using synthetic control methods'
Authors: Pepita Barlow, Martin McKee, Sanjay Basu, David Stuckler

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