Is it worth cutting salt for heart health?

By Anna Sayburn

BMJ Group News

What do we know already?

A low-salt diet can help to lower your blood pressure, which is why doctors recommend it, especially for people with high blood pressure who are at risk of having a heart attack or stroke.

But studies show that most people can only lower their blood pressure by a small amount - about 1 point - through a low-salt diet alone. Reducing your risk of heart attack or stroke usually requires a reduction of 2 to 3 points.

So is it worth cutting down on salt? A review of all the evidence looked at whether eating less salt resulted in fewer heart attacks, strokes or deaths, both for people with high blood pressure and those with normal blood pressure.

What does the new study say?

The review didn’t find any evidence that cutting salt from the diet made any difference to how long people lived, whether they had high blood pressure or not.

Neither did cutting down on salt make any difference to people’s chances of having a heart attack or stroke.

Worryingly, for people with heart failure, cutting down on salt actually seemed to increase their chances of dying. However, this finding came from just one fairly small study, so we need more evidence to be sure that it was not just a chance finding.

How reliable is the research?

The researchers looked at seven good-quality studies, which looked at almost 6,500 people in total. Pooling data from several studies tends to give very reliable results.

However, the researchers themselves say there is not enough evidence to rule out a benefit from cutting back on salt. They say more research is needed to find out whether a low-salt diet is harmful for people with heart failure.

What does this mean for me?

If you have high blood pressure, your doctor will probably recommend a low-salt diet. This study suggests that reducing salt alone may not be enough to make a difference to your chances of avoiding a heart attack or stroke. Blood pressure medicines may be needed as well.

Although the researchers didn’t find a big benefit from reducing salt, they do say that it’s likely that cutting salt would be beneficial for most people. Most of us eat much more salt than we need.