Natalie Riediger is an adviser with EvidenceNetwork.ca, an assistant professor in the Departments of Community Health Sciences and Human Nutritional Sciences and at the Manitoba First Nations Centre for Aboriginal Health Research, University of Manitoba.

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There has been increasing interest in the use of a sugar-sweetened-beverage tax to curb the burden of obesity in Canada – call it a "pop tax" if you like. A recent Senate report on obesity in Canada recommends assessing the possibility of a sugar-sweetened-beverage tax and points to the high rates of taxation on tobacco products as a successful example worth imitating.

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But have taxes on tobacco products been as successful as is often claimed?

While the prevalence of smoking has gone down considerably since the introduction of various smoking policies across Canada – taxation being just one of the major ones – upon closer inspection, the decrease in smoking has not been uniform across the population as a whole.

Over the last 30 years, more individuals of high socioeconomic status have quit smoking or not started smoking in Canada. However, during the same time period, the prevalence of smoking has decreased very little among populations of low socioeconomic status.

This gap is particularly evident for heavy smoking – 29 per cent of women with less than a high-school education were heavy smokers in 1974. This number dropped to only 24 per cent in 2005 – an improvement, but a very modest one.

In comparison, 18 per cent of women with a university degree were heavy smokers in 1974 and this number dropped to fewer than 3 per cent in 2005. This is despite the fact that individuals with lower income are disproportionately burdened by the tobacco tax.

The same pattern has been observed in the United States where, between 1996 and 2012, counties in the top income brackets experienced faster declines in smoking rates compared to counties with lower income levels. This pattern is not unique to North America either. European countries have observed the same socioeconomic disparities in changes in smoking prevalence over time.

So why didn't tobacco taxes work for people of lower socioeconomic status? Well, people don't smoke because it's cheap, just as people don't drink pop because it's cheap.

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Smoking makes people feel good in the short-term, as do sugar-sweetened beverages. Who doesn't enjoy an ice-cold cola? Ultimately, tobacco tax contributed to a societal change in the way smoking was viewed, which in turn pushed more people, especially people with resources and support, to quit or not smoke at all.

The effect of smoking policies, like taxation, have likely widened the health equity gap.

Smoking-related diseases – lung cancer, chronic obstructive pulmonary disease, diabetes and cardiovascular disease – disproportionately affect those with lower socioeconomic status. Using Canadian census mortality data, researchers have recently reported that death due to these specific diseases is substantially higher for individuals of lower income and education.

So back to the idea of a "pop tax." Will taxing sugar-sweetened beverages reduce obesity across Canada?

I predict a similar societal change in the way we view sugar-sweetened beverages if a tax is implemented. People with resources, support and education will be better situated to identify, afford, prepare and ultimately care about the food they eat. People of lower socioeconomic status, however, including the more than four million food-insecure Canadians, will more likely continue to focus on adequate access to food instead, as well as a home to prepare their food in.

Like the tobacco tax, the ultimate goal of a pop tax would be to improve health outcomes. Already we know that the burden of obesity, diabetes and cardiovascular disease are greater among populations of low socioeconomic status.

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In other words, a sugar-sweetened-beverage tax alone would likely do very little to improve population health outcomes if it fails to change behaviour among low socioeconomic populations. Unfortunately, there is currently no research that indicates otherwise and, unless there is, we should refrain from implementing the tax.

So what should be done instead? Policies geared to improve eating habits and, ultimately, public health, should focus on food security. Emerging evidence suggests that food insecurity results in greater health-care costs in comparison to overweight/obesity.

We need to look for solutions to benefit low-income and marginalized Canadians. These solutions will need to be developed in partnership with marginalized populations and will need to include roles for both government and industry. Slapping a pop tax on sugar-sweetened beverages looks like a quick fix, but is more Band-Aid than solution.