Dietary Salt Restriction May Be Detrimental to One’s Health (and a rebuttal in the journal Lancet)

For years the conventional medical wisdom has been to reduce salt intake for improved cardiovascular health and reduced hypertension risks.

Now it seems that limiting dietary salt may not only not work as advocated, but also be detrimental to one’s health.

From the 3 May  News@JAMA site (Journal of the American Medical Association)

May 3, 2011
Author Insights: Questioning the Benefits of Salt Restriction
Filed under: Cardiovascular Disease/Myocardial Infarction,Diet,Hypertension,Stroke — Mike Mitka @ 4:09 pm

Research by Jan A. Staessen, MD, PhD, of the University of Leuven in Belgium and colleagues, raises questions regarding whether population-wide sodium restriction will actually lower cardiovascular risks. (Image: University of Leuven)

Research by Jan A. Staessen, MD, PhD, of the University of Leuven in Belgium and colleagues, raises questions regarding whether population-wide sodium restriction will actually lower cardiovascular risks. (Image: University of Leuven)
National policies that advise restricting sodium (salt) intake to reduce the risk of hypertension might not provide the anticipated cardiovascular benefits and may even be detrimental to health, report researchers in an article in today’s JAMA.
In the study, the researchers categorized the 3681 study participants according to sodium intake, using a procedure that measures sodium in the urine over a 24-hour period, considered the gold standard for such assessment. At a median of nearly 8 years later, participants in the group with the lowest sodium intake at the beginning of the trial were significantly more likely than the other 2 groups to die of cardiovascular disease.

The researchers also found that these 3 groups had the same risk of developing hypertension, regardless of initial sodium intake. They did find in a subgroup of 1499 study participants who had sodium intake measured at the beginning and at the end of the study that an increase in sodium intake was associated with an increase in systolic (but not diastolic) blood pressure. However, this relationship did not result in a higher risk of complications from hypertension or cardiovascular disease, such as heart attack or stroke.

Jan A. Staessen, MD, PhD, professor of medicine at the University of Leuven in Belgium and one of the study’s authors, discusses his team’s findings:

news@JAMA: Are you surprised by your results?

Dr Staessen: Not so much. We started this research more than 25 years ago, and in all our studies, it was almost impossible to find an association between blood pressure and 24-hour sodium excretion. We were a bit surprised to see an inverse relationship between sodium intake and cardiovascular death.

news@JAMA: Why would lowering sodium intake possibly increase cardiovascular risk?

Dr Staessen: Ours is an epidemiological study so we cannot be sure of the underlying mechanism. But if you decrease sodium intake a lot, you activate some of the systems that conserve sodium and they are known to have a negative influence on cardiovascular outcomes. This may be an underlying mechanism.

news@JAMA: Where does your study fit into the discussion of mandating sodium restriction in foods to improve health, as advocated by some public health officials and government agencies?

Dr Staessen: One should be very careful when one wants to implement [sodium restriction], as it is based on short-term studies mainly in hypertensive populations. Whether one can extrapolate these short-term results over the long term remains to be seen, especially as our study and 2 previous studies have shown an inverse association between sodium intake and mortality.

news@JAMA: What is needed to provide a clearer picture of the benefits and risks of controlling sodium consumption?

Dr Staessen: What one needs is a long-term interventional study to look at cardiovascular complications. Reducing blood pressure is not what one is in this for. You want to show that it actually changes cardiovascular outcomes.

Related articles

• The Science Is Settled (maxredline.typepad.com)

• Less Salt, Less Strokes, Says New Research (Science Daily, August 11, 2011)

• To Salt Or Not To Salt, That Is The Question (Medical News Today, June 2011)
• Eat Less Salt – and Die? (psychologytoday.com)
• Is the war on salt justified? (macleans.ca)
• Heart Benefits From Cutting Back on Salt? (webmd.com)

        “A new eight year long European study concludes that salt consumption is not dangerous and may in fact be beneficial. This is certainly contrary to advice from American Medical Association, American Heart Association and the Center for Disease Control and Prevention, which says higher sodium consumption can increase the risk of heart disease. It’s not unusual to see differing opinions, but what are we ordinary folks to make of the controversy? The study followed 3,681 middle-aged Europeans who did not have high blood pressure or heart disease at the start of the study…”

• High Potassium-To-Sodium Ratio May Reduce Risk Of Cardiovascular Disease (Medical News Today, 6 May 2011)
• False Assumption That Salt is “Bad” For Us Is Creating Iodine Deficiency (Health and Well-Being Blog)
• High salt diet ‘lowers heart disease risk’ (news.bioscholar.com)
• ‘Salt intake drop could increase chances of heart disease’ (dailymail.co.uk)
• Cochrane Salt/Blood-Pressure Message Blasted in the Lancet “July 28, 2011 (London, United Kingdom) — Two preventive-medicine experts in the UK are crying foul over a recent and controversial meta-analysis that concluded cutting salt consumption would have no clear health benefits [1]. In a Comment published in the July 30, 2011 issue of theLancet, Dr Feng J He (Queen Mary University, London, UK) and Dr Graham A MacGregor(Wolfson Institute of Preventive Medicine, Barts, London, UK) say that the meta-analysis published simultaneously by Taylor and colleagues in the Cochrane Review [2] and the American Journal ofHypertension [3] and press release that accompanied it “reflect poorly on the reputation of the Cochrane Library and the authors.””…….
• Eat Less Salt – and Die? (psychologytoday.com)
• Is the war on salt justified? (macleans.ca)
• Heart Benefits From Cutting Back on Salt? (webmd.com)