GUEST BLOG: LINDSAY MCLAREN
Dr. Lindsay McLaren looks at the links between sodium and social inequalities:
It is well-documented that many populations worldwide consume too much sodium in their diet. Among Canadian adults, for example, over 85% of men, and over 60% of women consume sodium in excess of the recommended upper limit of 2,300 mg/day (1).
From a public health point of view, another, equally important, concern is whether social inequalities in sodium consumption exist. In other words, do those with fewer social and economic resources (e.g., income, educational attainment) consume even more sodium than those with more resources?
While it seems likely that social inequalities in sodium consumption exist (think of processed, ready-to-eat, salty foods that tend to be cheap), there has been surprisingly little research on the topic.
A new study(2) from the U.K. tackles the question. Using data from 2,105 adults from the 2000-01 British National Diet and Nutrition Survey, Ji and colleagues examine the relationship between socioeconomic position (educational attainment, and social class) and sodium intake. Sodium intake was measured using a diet survey, as well as by a 24-hour urine sample. Ji and colleagues found an association between lower socioeconomic position and higher sodium intake, even taking into account other factors such as age, sex, age, marital status, and geographical location.
The authors note that their data pre-date Britain’s national salt reduction strategy, which was introduced in 2003 and which has contributed to an average reduction in salt consumption of nearly 1.5g/day. They comment that “it would be important to repeat our analyses … to document whether the reduction in salt intake seen over the past few years has modified the social inequality in salt consumption observed previously”. In fact, another study, by Millet et al.(3) investigated that topic, and found that the reductions in salt intake tended to be “uniform” across social class and ethnicity. These findings speak to the importance and urgency of a national sodium reduction strategy in Canada, to reduce sodium consumption across the population in a way that does not worsen social inequalities in intake (see related post by Dr. Norm Campbell, Will Canada continue to ignore WHO sodium reduction guidelines?).
Do social inequalities in sodium consumption exist in Canada? Possibly. A challenge with answering this question in Canada is that the national nutrient database, which is used to estimate how much sodium individuals consume, is based on an “average product” for each food item. That means that person A who consumes “regular” brand x crackers, and person B who consumes “low-sodium” brand x crackers, would be assigned the same sodium value for that food item. To the extent that consumption of “low-sodium” products is related to SES, social inequalities in sodium consumption will be masked. Nonetheless, my research team(4) is currently in the process of doing the best we can to answer this important question – results coming soon!
1 Garriguet D. Sodium consumption at all ages. Health Reports 2007;18:47-52.
2 Ji C, Kandala N-B, Cappuccio FP. Spatial variation of salt intake in Britain and association with socioeconomic status. BMJ Open 2013;3:e002246.
3 Millett C, Laverty AA, Stylianou N, Bibbins-Domingo K, Pape UJ. Impacts of a national strategy to reduce population salt intake in England: serial cross-sectional study. PLoS ONE 2012;7: e29836
4 McLaren L, Lorenzetti D, McIntyre L, Tarasuk V, Emery JCH, Campbell N. Population-level prevention and implications for socioeconomic inequities in health: dietary sodium as a case example. Canadian Institutes of Health Research Operating Grant # 201103SOK-254910-PHI-CBBA-58728
Dr. Lindsay McLaren
Associate Professor and Alberta Innovates – Health Solutions Population Health Investigator
University of Calgary Department of Community Health Sciences, Faculty of Medicine
Dr. Lindsay McLaren’s research, which is presently funded by CIHR and Alberta Health & Wellness, focuses on conceptual and empirical questions related to population health and social inequalities in health, including the social determinants of body weight and related outcomes. She is also the President-Elect of the Alberta Public Health Association and the Associate Director of the Population Health Intervention Research Centre at the University of Calgary.