eMJA: The 100-year conflict: salt intake and cardiovascular disease

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The 100-year conflict: salt intake and cardiovascular disease

MJA 1998; 169: 174-180

The health effects of dietary salt have long been debated. As early as the beginning of the 20th century, salt restriction was used as a therapeutic measure, first for oedema and then for hypertension, particularly in France.¹ Later, in the United States, the benefits of low salt diets for patients with hypertension and renal disease were championed by Allen in the 1920s and 30s and by Kempner in the late 1930s and 40s.¹ However, not all investigators were convinced of the value of these diets, and the hazards of overzealous and prolonged salt restriction were also appreciated.¹
By the 1960s and 70s, studies linking an increase in blood pressure of indigenous populations with the introduction of salty Western diets persuaded government bodies to recommend reduced salt as part of healthy dietary guidelines. One of the eight Dietary Goals for Australia, announced in 1979 by the then Commonwealth Department of Health, was "Decrease consumption of salt".²
There are, however, many researchers who maintain that there is insufficient evidence of benefit to recommend universal salt restriction. A summary of this controversy, described as "a philosophical clash between the requirements of public health policy and the requirements of good science", appeared in Science last year.³
In the MJA the salt controversy is alive and well. A study by Beard et al published in 1997 showing a low level of conformity with the year 2000 dietary salt target for Australians (<100mmol/day)⁴ brought an immediate response from Kincaid-Smith, reminding readers of the possible dangers of low salt intake.⁵
Then, in March 1998, a study by Alderman et al in the Lancet, claiming to have found an inverse association between dietary salt intake and all-cause and cardiovascular disease mortality,⁶ revived the international controversy, to which the Lancet's letters columns attest.^7-10
Here, we present our own salt debate, with three views of the value (or otherwise) of salt restriction as part of a healthy diet.

Universal recommendations for sodium intake should be avoided
Restriction of salt intake is needed too ameliorate the cardiovascular disease epidemic
The salt dilemma: some answers, many questions
Link to salt debate references
Photo of chimpanzee
Dr Derek Denton showed unequivocally that increased salt intake causes a substantial rise in blood pressure in chimpanzees.¹¹

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