Consuming twice the maximum daily salt recommended by the NHS may be safe, a controversial new study has claimed.

A major review published in the Lancet suggests that salt is not as damaging to health as previously thought and that official campaigns should focus only on those consuming the most.

The NHS and World Health Organization say adults should not have more than a teaspoon of salt a day, because of the risk of heart attacks and strokes.

But the new study indicates that up to two and a half teaspoons of salt may be safe, and that more than this may still be acceptable as part of a broader healthy diet comprising lots of fruit and vegetables.

The study analysed the data of 94,000 people in 18 countries, whose sodium levels was measured using urine tests.

However, experts have said the method used to estimate salt intake is not reliable and that a preponderance of Chinese participants in the study may be prejudicing the results.

“Our study adds to growing evidence to suggest that, at moderate intake, sodium may have a beneficial role in cardiovascular health, but a potentially more harmful role when intake is very high or very low,” said Professor Andrew Mente, who led the study at McMaster University.