03 Apr Too Little and Too Much Salt Associated with Increased Mortality
MedicalResearch.com Interview with:
Niels Graudal, MD, DrMSc
Department of Internal medicine/Infectious Medicine/Rheumatology IR4242
Copenhagen University Hospital, Rigshospitalet
Dr. Graudal: There are no studies, which show what happens with the risk of cardiovascular death or mortality if you change your sodium intake. Our study shows the association of sodium intake as it is with cardiovascular disease and mortality, which is only the second best way to consider the problem, but as the best way does not exist we have accepted this approach. There have been two different assumptions concerning the risks of sodium intake. One is that there is an increasing risk of heart disease, stroke and death of salt intake above 2300 mg, and one is that salt is not dangerous at all. Our study shows that both positions partially may be true, as a salt intake above 4900 mg is associated with increased risk of cardiovascular disease and mortality, whereas the present normal salt intake of most of the world’s populations between 2300 mg and 4900 mg is not associated with any increased risks. In addition our study shows that a low sodium intake below 2300 mg is also associated with increased risk of cardiovascular disease and death.
Dr. Graudal: I was not surprised that the risk of a high sodium intake starts at a much higher level than the arbitrary 2300 mg suggested by CDC, WHO and AHA, which in my opinion always has been unrealistically low, and never verified by scientific evidence. 500 mg of sodium is sufficient for the body to function, but at that dose the kidneys and the adrenal glands pumps out large amounts of salt conserving hormones (renin and aldosterone) into the blood stream, strongly indicating that although functioning, the body is not satisfied. “Sufficient” is not the same as “optimal”. This pumping out of hormones does not stop before the dose of sodium intake is about 2300 mg. Therefore the increased risk below 2300 mg is also not surprising.
Dr. Graudal: I have been a clinician for 35 years, but I have never met a colleague, who recommended their patients to reduce sodium intake unless the patient suffered from hypertension or heart insufficiency. With modesty this strategy could be continued. I do not think that clinicians should recommend general sodium reduction for everybody. Individuals could consider whether they would follow the public recommendations to reduce salt intake to the level recommended, i.e. below 2300 mg, since this level is associated with increased mortality. Finally, both clinicians and individuals could consider that our study also showed that compared with many other risks of everyday life the increased risks of a low and a high sodium intake are not big. So maybe they should just consider more important aspects of their lives than the sodium intake.
Dr. Graudal: In reality, the issue of sodium intake is a storm in a glass of water, but it has become an industry for bureaucrats in health organizations, who eagerly-but not with reason-defend their positions. It is about time that some politicians with sense and power stop this circus and maybe associate this with an upper tolerable sodium intake level of about 4900 mg. One might consider clinical trials in patients with hypertension and heart disease to find out whether sodium reduction (but not necessarily below 2300 mg) in these selected groups might have a favorable effect on morbidity and mortality.
N. Graudal, G. Jurgens, B. Baslund, M. H. Alderman. Compared With Usual Sodium Intake, Low- and Excessive-Sodium Diets Are Associated With Increased Mortality: A Meta-Analysis. American Journal of Hypertension, 2014; DOI: 10.1093/ajh/hpu028