Letter: Pinch of salt

I was interested to read your report that reducing "excessive" salt in food can reduce heart disease by 20 per cent (2 November). This would be astonishing, in view of the fact that the level of salt in the body is regulated by a very efficient servomechanism.

Salt is a an essential component of any healthy diet. Losses in blood, sweat and tears are made good from dietary salt and if we ingest too much salt, we become thirsty, drink more water and excrete more salt. I have encountered reports of agricultural research work in which it was found to be impossible to harm pigs fed on salt-rich swill, as long as they were provided with access to an adequate supply of fresh water.

It is quite unnecessary for a healthy human being to attempt consciously to regulate dietary salt intake on a formulaic basis.

(Dr) David Purves

Strathalmond Road

Edinburgh