Letters Reducing population salt intake

The sodium phantom

BMJ 2011; 343 doi: http://dx.doi.org/10.1136/bmj.d6119 (Published 27 September 2011) Cite this as: BMJ 2011;343:d6119
  1. Niels Graudal, senior consultant1,
  2. Gesche Jürgens, MD2
  1. 1Department of Rheumatology, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark
  2. 2Department of Clinical Pharmacology, Bispebjerg University Hospital, Copenhagen
  1. graudal{at}dadlnet.dk

Cappuccio and colleagues’ analysis is unbalanced.1 Firstly, the mean sodium intake in population studies that found a lowering effect of sodium reduction on blood pressure was above 250 mmol. Therefore these results cannot be applied to most of the world’s populations, which have a mean intake of about 150 mmol.2 In a population with a normal sodium intake, sodium reduction had no effect on blood pressure.3

Secondly, the fall in blood pressure and increased survival in Finland probably have nothing to do with reduced sodium intake, because in other parts of the world a 50% increase in sodium intake was associated with a fall in hypertension prevalence from 30% to 15%.4

Thirdly, “healthy physiological requirements of salt” may not be 1 g per day. Populations on minimal salt intake have extreme activation of the renin-aldosterone system and an increase in lipids and catecholamines.5

Fourthly, Strazzulo and colleagues’ meta-analysis did not report an analysis of all cause mortality, which would have shown an increased trend with low sodium intake.1

Fifthly, the calculations of lives to be saved by sodium reduction are based on dubious assumptions from selected studies and contradicted by new population studies,6 which show increased all cause mortality with low sodium intake.

Blood pressure is normal in 85% of the population,4 so it is essential to determine whether sodium reduction significantly affects blood pressure in normotensives before advising general sodium reduction. Given the possible side effects of sodium reduction,5 6 this effect is not sufficient to recommend general sodium reduction. It is surprising that many countries have uncritically adopted sodium reduction, which probably is the largest delusion in the history of preventive medicine.

Notes

Cite this as: BMJ 2011;343:d6119

Footnotes

  • Competing interests: None declared.

References