Chockalingam on Global Challenges for Reducing Sodium Consumption
The relationship between salt and blood pressure has long been known. As early as 2000 BC the Chinese “Yellow Emperor” Huang Ti recorded salt’s association with a “hardened pulse.” As land-based creatures, humans do not require much sodium to sustain our physiology (no more than 50 milligrams of sodium a day) but today many people around the world are consuming 10-15 grams of salt a day. About 75% of this comes from processed foods; about 10% derives from the natural salt content of food; while about 15% is added during cooking or on the table.
Historically, salt was valued because it could preserve foods. With the advent of refrigeration, heavy use of salt has been rendered unnecessary but the taste for salt remains. For example, working in Newfoundland in the 1990s showed that the diet of Newfoundlanders was heavily laden with salt. Through much of its history, Newfoundland was a poor province and the only way to preserve meat was to salt it then dry it in the sun. A local delicacy called the “jigs dinner” contained meat, potatoes, and turnips which were boiled over 24 hours in salted water. Fish was prepared with a coating of animal fat drippings, bread crumbs, and salt, then deep-fried.
Even after refrigeration became commonplace, many populations around the world had acquired a taste for salt over several generations, and local diets remained extremely salty. Worldwide today, salt is used as an inexpensive way to enhance the flavour, texture, and shelf life of foods. Because salt and sodium phosphates increase the water-binding capacity of meat products, it increases the weight and thus the profit margin of food. Because salty snacks induce thirst, they also increase sales of beverages which are often also unhealthy.
In Newfoundland in the late 1980s, the study INTERSALT examined the salt intake, blood pressure, and other physiological parameters of 52 populations in 45 countries. Newfoundlanders consumed the highest amount of salt per day of any of the groups studied roughly 18.5 grams per day per person. They also demonstrated corresponding higher levels of blood pressure, CVD mortality, and stroke rates. While sodium had long been thought to be a risk factor for CVD mortality, INTERSALT was the first population-based comparative study to directly associate salt with hypertension. Its findings lent further support to recommendations for mass reduction of high salt intake for the prevention and control of adverse blood pressure levels ensuring cardiovascular complications in populations.
Over the past 20 years, community interventions and health promotion messages have demonstrated the efficacy of strategies to reduce salt consumption. The North Karelia Project promoted salt reduction by individuals and by manufacturers of widely consumed products like bread, resulting in a drastic reduction in cardiovascular mortality and morbidity. Finland was a small country and at the time was not experiencing any significant globalization, so it was feasible to influence food processing as well as individual behaviour.
The World Hypertension League works on a global scale to increase awareness of the relationship between salt, hypertension and stroke. The theme for World Hypertension Day on 17 May 2009 is salt reduction (www.worldhypertensionleague.org).
While local and national advocacy are critical to creating change, a global approach to salt reduction is essential. Consider these examples of lower sodium content in UK versions of some common food products, compared with the sodium content of the same foods in Australia: Kellogg’s Coco Pops in the UK have 25% less salt than those sold in Australia; Burger King onion rings have 150% less salt and a McDonalds cheeseburger in Australia contains 21% more salt than the same burger in the UK.
This demonstrates the global implications of national policy. The Policy Framework Statement developed by the National Forum’s Regional and Global Collaboration Implementation Group recommends that “US institutions should follow guidelines that help ensure effectiveness in reducing the cardiovascular disease epidemic not only in the US but also globally. As far as possible, these guidelines should become the basis for US policy with regard to global cardiovascular health.” Clearly, these recommendations should be extended to other countries that dominate the global marketplace.
Much can be and must be done to reduce population burden of high blood pressure and associated heart diseases, stroke, kidney, and other vascular diseases. Labeling, if it exists, is frequently confusing. Daily sodium limits on food labels are sometimes higher than recommended levels, and serving size information can be deceptive. Public education on how to read food labels should be undertaken by health professionals and NGOs. Prevention should start at a very early age. Parents can be educated on the importance of not exposing children to excessive salt. People can remove salt shakers from the table and minimize what they use while cooking. At local and national levels community coalitions can find ways to promote salt reduction and encourage food manufacturers to reduce the dependence on salt as a preservative and use healthful spices to enhance flavour.
A December 2007 article in The Lancet (Lancet 2007; 370:2044-52) examined two interventions to reduce salt intake in the population by 15%, and to implement four key elements of the WHO Framework Convention on Tobacco Control. Based on a mathematical modeling on 23 lower- and middle-income countries that account for 80% of chronic disease burden in developing countries, the study showed that over 10 years (2006-2015) 13.8 million deaths could be averted by implementing these two simple interventions, at a cost of US$0.40 per person per year in low-income and lower-middle income countries; and less than US$1.00 per person per year in the upper-middle-income countries. These two interventions are achievable and all it takes is the collective public and political will. (Arun Chockalingam)
Asaria, P., Chisholm, D., Mathers, C., Ezzati, M., Beaglehole, R. 2007. Chronic disease prevention: health effects and financial costs of strategies to reduce salt intake and control tobacco use. Lancet 370:2044-52.
World Health Organization. Reducing salt intake in populations: Report of a WHO forum and technical meeting. Geneva: WHO. 2007.