For decades experts have peppered people with warnings about the amount of salt being consumed.
Scientists agree too much of it can raise blood pressure , which is linked to a higher risk of heart disease and stroke.
The NHS and World Health Organisation say adults should not have over a teaspoon of salt per day – but a controversial study has suggested up to two-and-a-half teaspoons is not a danger.
The researchers also concluded eating a lot of fruit and veg may eliminate the risk of heart attacks and strokes from more than two-and-a-half teaspoons.
Study author Professor Andrew Mente, of McMaster University in Canada, said: “Only in the communities with the most sodium intake… did we find a direct link between [it] and major cardiovascular events like heart attack and stroke.” Sodium is the active ingredient in salt.
They found cardiovascular problems were lower in places with a high level of potassium consumption. Foods high in potassium include fruit and veg.
One problem is many processed foods are high in salt but rarely eaten with a lot of veg. The findings, published in The Lancet, involved a study of 94,000 people in 18 countries including China. Salt intake was measured with urine tests.
Tam Fry, of the National Obesity Forum, said Prof Mente has been criticised in the past for his advice, so “you would be best to stay within the UK’s official guidelines for the time being”. Exeter University health expert Prof Rod Taylor said: “The findings were observational so cannot claim cause and effect.
“[And] they were limited to a mostly Asian population, so we don’t know how widely applicable they might be.”
‘Take research with a pinch of salt’
Comment by DR GUNTER KUHNLE , nutrition expert
This large observational study has confirmed what is already known about high salt intake – it results in higher blood pressure and an increased risk of cardiovascular diseases.
It also confirms very low salt intake can affect health badly, which is the case for most nutrients. The main limitation of the study is how salt intake was measured.
The method used in the research is not suitable to estimate salt intake reliably. It is therefore not possible to identify an optimal range of intake based on the data or to assess whether the current WHO recommendation is sufficient.
The accurate assessment of salt intake is notoriously difficult because there are many dietary sources. An alternative is to measure salt excretion in urine. There are methods to estimate 24-hour salt excretion from morning or spot urine samples, such as those used in this study, but they are known to be unreliable.
- Dr Kuhnle is a professor in nutrition and health at the University of Reading.
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