Less salt means lower risk of BP and heart attack, says study

Mankind has never been able to agree on whether salt consumption is good or bad, but the first long-term study of salt's impact on health has confirmed that eating less salt reduces the chances of a heart attack or stroke.

The results of the study have been published in the British Medical Journal.

Scientists say the results from a 15-year long study are the clearest proof yet that reduction in salt intake has a direct and positive bearing on cardiovascular disease.

The study showed that those who ate less salty food have as much as 25 per cent less chance of cardiac arrest or stroke, and consequently a 20 per cent lower risk of early death.

While it has been accepted that cutting down salt reduces blood pressure – and consequently a reduction in heart attacks and strokes – so far no study has conclusively linked up the two.

The findings reported by the BMJ are courtesy an American team from Harvard Medical School led by Nancy Cook. The team went into two trials conducted in the late 1980s and early 1990s that measured how much blood pressure fell on cutting salt intake, and reported that it was as much as 25-35 per cent.

'Our study provides unique evidence that sodium reduction might prevent cardiovascular disease and should dispel any residual concern that sodium reduction might be harmful,' the study concludes.

The first trial had 327 healthy men and women aged between 30 and 54 take part; they were compared to 417 who did not. The study found only a slight fall in the blood pressure of the 327, and the original authors of the study were not sure if the reduction would be sustained. According to their estimate, if the reduction in salt intake was sustained it would reduce death by stroke by six per cent, death by heart disease by four per cent.

Interestingly, Dr Cook's team, after following up on the trials, showed that those who cut down their salt intake did report a much lower risk of heart disease and stroke, and much more marked health benefits.

But the salt manufacturers are not buying these findings, and point out that how consumption of salt increases blood pressure is still a matter of dispute. The common explanation is that when intake of salt is too high, the kidneys are unable to eject it all through urine, with the result that some of it ends up in the blood stream. This leads to more water being drawn into the blood, which increases volume and hence pressure.

Again, since everyone has different levels of sensitivity to salt, the benefits from reducing salt consumption will also vary, manufacturers point out.