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Researchers at the University of Toronto have found that sodium levels in Canadian chain restaurant meals have changed little since 2010, despite the food industry’s commitment to offer more meals with less sodium.

The researchers analyzed nutrition information from 61 sit-down and fast-food restaurants in 2013 and found that compared to levels in 2010, 54 per cent of foods did not change. In 30 per cent of foods, the amount of sodium decreased marginally and in 16 per cent of foods, levels increased.

Most important, the research showed that the number of foods exceeding the U.S. Institute of Medicine’s recommended daily intake did not change.

“Despite some improvements, the number of foods containing more than a day’s worth of sodium hasn’t changed,” said Mary Scourboutakos (pictured at left), a doctoral student in U of T’s department of nutritional sciences and lead author of the study. “The increases and decreases we observed in sodium in various foods and restaurants shows that the current voluntary approach to decrease sodium in restaurant foods has produced inconsistent results.”

Limiting salt intake is important because high dietary sodium is a risk factor for hypertension, which is the leading preventable risk factor for death worldwide. Some research has also linked salt consumption to stomach cancer, osteoporosis, kidney stones and other health conditions.

The researchers compared changes in sodium levels in more than 2,100 foods over the three years. They then compared those levels to the daily adult adequate intake of 1,500 milligrams (mg) and the tolerable upper limit of 2,300 mg per day. The average change among foods that decreased was 200 mg, a 19 per cent decline. The average increase in foods with more sodium was 251 mg, a 44 per cent increase.

There was some good news in the results. The researchers found that overall there was a slight decrease in sodium levels, both per serving (due to smaller portion sizes) and per 100 grams (i.e., sodium density). However, despite this progress, the increased levels in certain foods often offset the improvements. Furthermore, the number of foods containing a “healthy” amount of sodium did not increase, highlighting the need for further improvement.  

“This study is important because Health Canada has not yet set targets for restaurant foods — a major gap in our Canadian sodium reduction efforts,” said Professor Mary L’Abbé (pictured at right) chair of the department of nutritional sciences and senior author on the study.

“This study reinforces the importance of labelling sodium information on restaurant menus, as research in other jurisdictions has shown that labelling legislation that includes sodium has encouraged restaurants to reduce their sodium levels.”

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Recently, provincial politicians introduced two menu-labelling bills in Ontario. Ontario’s Associate Minister of Health and Long-Term Care, Dipika Damerla, introduced a bill that calls for calorie on restaurant menus. Another bill by New Democratic Party MPP France Gélinas calls for calorie labelling and warning labels for foods that are high in sodium.

The study was published by CMAJ Open, an online open-access offshoot of the Canadian Medical Association Journal.

Jim Oldfield is a writer with the Faculty of Medicine at the University of Toronto.