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Canadians consume a large amount of sodium. Although some sodium is needed to control blood volume and to help cells function properly,1 most Canadians consume far more than is necessary, or recommended. Results from the 2004 Canadian Community Health Survey (CCHS — Nutrition (see Data source) indicate that, among people aged 19 to 70, over 85% of men and 60% of women had sodium intakes exceeding the recommended upper limit beyond which health risks increase (Table 1).
Most sodium is consumed as sodium chloride, usually called “table salt.” In fact, a US study has estimated that 90% of sodium intake comes from sodium chloride.2 Processed foods are the main source, accounting for 77% of average daily sodium intake. Another 12% occurs naturally in foods, and salt added during cooking (6%) or at the table (5%) makes up the remainder.2
The Institute of Medicine (IOM)1 recommends the following “adequate intakes,” or AIs, per day:
The IOM has also established a “tolerable upper intake level,” or UL (see Definitions and Limitations), which ranges from 1,500 mg to 2,200 mg of sodium per day for children and adolescents aged 1 to 13, up to 2,300 mg per day for people aged 14 or older. Consumption exceeding these limits increases the risks of adverse health effects, especially those linked to hypertension.1
Information on Canadians’ sodium consumption was gathered as part of the 2004 CCHS — Nutrition 24-hour “dietary recall.” Respondents were asked to list everything they ate or drank the day before they were interviewed for the survey (see The questions). Information for children younger than 6 was collected from their parents, and interviews for children aged 6 to 11 were conducted with parental help. When parents were unable to provide the details (for example, foods/beverages eaten at daycare or at school), they were asked to get as much information as possible from those who had been in charge of their child(ren). The sodium content of food was taken from Health Canada’s Canadian Nutrient File 2001b, Supplement.9
In 2004, regardless of their age, Canadians’ average daily intake of sodium was far beyond the recommended UL (Chart 1). Males consumed more sodium than females, with intakes above 4,000 mg/day for those aged 14 to 30. Among people aged 9 to 70, over 85% of males and between 60% to 80% of females had usual sodium intakes that surpassed the recommended UL (Table 1).
Even young children consume too much sodium. Children aged 1 to 3 averaged close to 2,000 mg a day in 2004. In this age group, 77% of children exceeded the recommended daily UL. Among 4- to 8-year-olds, daily intake averaged 2,700 mg, and 93% had consumed more than the UL. For most of these children, adding salt at the table was not contributing to the high sodium intake levels. According to the CCHS, 69% of 1- to 3-year-olds and 52% of 4- to 8-year-olds “never” added salt to their food.
By age 9, children were beginning to adopt the adult habit of adding salt to their food. From this age onwards, the percentage of people saying they “never” salted their food at the table dropped to around 30% (Table 2).
The amount of salt people added to their food was not measured by the CCHS and it was not included in daily sodium intake. Yet it was the people who were already consuming the highest amounts of sodium in the foods they ate who reported most frequently (“very often”) adding salt (Chart 2). Respondents who said they “never” added extra salt were consuming much less sodium in a day. Even so, the percentage in this group with levels beyond the recommended UL was almost the same as that for the population as a whole (data not shown).
A number of studies have shown a link between sodium intake and hypertension.1 When sodium intake rises in susceptible individuals, blood pressure tends to increase. Hypertension is usually diagnosed sometime after age 31; in the 2004 CCHS — Nutrition, 6% of 31- to 50-year-olds reported having been diagnosed with high blood pressure. For the 51-to-70 and 70-or-older age groups, the estimates rose to 27% and 47%, respectively.
The results from the CCHS question about adding salt to food at the table suggest that people aged 31 or older who had been diagnosed with hypertension seem to be aware that they should reduce their salt consumption. They were significantly less likely to report salting their food either “occasionally” or “very often” (Chart 3).
Although it may be more visible, salt added at the table actually accounts for only a small amount (5%) of daily sodium intake.2 When the source of sodium was less obvious because it was already in the food, the intake of adults with hypertension was similar to that of people without the condition (data not shown). Excluding added salt, the usual sodium intake of adults with hypertension was well above the recommended UL.
Increased sodium intake has been linked with high blood pressure, but increased potassium intake can help reduce blood pressure.1 However, the CCHS results indicate that Canadians’ potassium intake, regardless of age and sex, is lower than recommended (data not shown).
Sodium consumption exceeds the recommended levels throughout the country, but two provinces stand out. In Quebec and British Columbia, the 2004 average daily intake for residents aged 1 or older was more than 3,300 mg versus 3,092 mg for Canadians overall. In Ontario, the only province where average daily sodium consumption was significantly below the Canadian figure, average intake was 2,871 mg (Chart 4) — still above the recommended daily UL. Provincial differences did not change when the sexes were considered separately (data not shown). (The CCHS — Nutrition did not cover the three territories.)
The Canadian diet — 10 main sources of sodium
Results from the 2004 CCHS — Nutrition indicate that the following 10 groupings of foods/beverages accounted for over half (55%) of all sodium tht Canadian consumed:
A comparison of estimates based on the 2004 CCHS and results based on the 2001-2002 National Health and Nutrition Examination Survey (NHANES) in the United States12 indicates that Canadians consume slightly less sodium than do Americans. Canadian levels were lower for children aged 1 to 8, men aged 31 to 70, and women aged 19 to 30. No Canada — US differences were observed for the other groups (Table 3).
These differences may have been slightly greater if the Canadian and US surveys had made the same adjustments when processing their data. The US approach adjusted the salt content of recipes downward, based on the frequency with which salt is added to foods during cooking, but the CCHS did not do so.