A Californian population based study has found that if everyone in the US reduced their daily salt intake by 3 grams – half a teaspoon – the annual number of deaths could be slashed by up to 92,000. In addition, the number of new people who get cardiovascular disease each year could drop by up to 120,000 – that’s equivalent to the population of Cambridge!
In fact, cutting dietary salt intake by as little as 1 gram a day could reduce the number of deaths from any cause by 15,000 to 32,000 and the number of new cases of cardiovascular disease by 20,000 to 40,000.
US regulations recommend that people consume less than 5.8 g of salt a day, yet the average American man gets through almost double that – 10.4 g of salt daily. This is bad news – high salt intake is associated with an increased risk of stroke and cardiovascular disease.
In this study, published in the New England Journal of Medicine, the authors used computer modelling to simulate heart disease and stroke in US adults aged 35-84 years.
They found that a population wide reduction in dietary salt of 3 g per day could potentially reduce the annual number of cases of cardiovascular disease by 60,000 to 120,000, stroke by 32,000 to 66,000, and heart attack by 54,000 to 99,000. The annual number of deaths from any cause could be cut by by 44,000 to 92,000.
Even a modest reduction of 1 g of salt per day could cut the yearly rates of cardiovascular disease, stroke, and heart attack by at least 20,000, 18,000, and 11,000, respectively. “It was a surprise to see the magnitude of the impact on the population, given the small reductions in salt that we were modeling,” Kirsten Bibbins-Domingo, lead author of the study, told Science Daily.
The effects seemed greater in black people – a population with high rates of hypertension and cardiovascular disease – and women would benefit in particular from a reduction in stroke incidence. The number of events related to cardiovascular disease – such as heart attack – would drop in older adults, whereas young people would benefit from lower overall mortality rates.
The public health benefits of a drop in salt intake of 3 g a day would be equivalent to half of all smokers quitting or a 5% reduction in body fat among obese adults, and would save $10 billion to $24 billion a year in healthcare costs.
“Reducing dietary salt is one of those rare interventions that has a huge health benefit and actually saves large amounts of money,” said senior author Lee Goldman. “At a time when so much public debate has focused on the costs of health care for the sick, here is a simple remedy, already proven to be feasible in other countries.”
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Bibbins-Domingo K et al. (2010) Projected Effect of Dietary Salt Reductions on Future Cardiovascular Disease. New England Journal of Medicine DOI: 10.1056/NEJMoa0907355
1 Comment
Interestingly, the Journal of the American Medical Association has just published a commentary urging caution in recommending reducing dietary salt:
http://jama.ama-assn.org/cgi/content/short/303/5/448?home
Elizabeth Loder, a BMJ research editor, writes of the article: “This commentary in JAMA suggests we should be cautious in urging universal sodium reduction. The author points out that the data in support of this strategy come from observational studies and are conflicting.”
http://blogs.bmj.com/bmj/2010/02/05/what-were-reading-5-february-2010/
The NEJM study I’ve discussed in this blog post is only a modelling study, not one that looked at actual patients, so doesn’t add any concrete evidence to the current knowledge. Modelling study + observational study = not a solid evidence base. As the author points out, “skeptics of the benefits of limiting dietary sodium argue that a recommendation to reduce sodium intake should be based on solid direct evidence that universal salt reduction will lower morbidity and mortality, be safe, and prevent otherwise dire consequences.”