Would switching to a salt substitute reduce stroke, heart attacks and deaths?

This study was one of the largest to look at changes to the diet ever conducted. It was carried out by researchers at The George Institute for Global Health and published in The New England Journal of Medicine.

We already know there is a link between a diet high in salt, raised blood pressure and heart and circulatory diseases. The researchers wanted to understand the impact of switching to a salt substitute on people’s health. Salt substitutes contain less sodium chloride and have added potassium chloride, are already available in supermarkets, and taste like normal salt.

This study followed 21,000 Chinese adults from 600 villages, who had either a history of stroke or poorly-controlled blood pressure, over almost five years. People in some of the villages were given a salt substitute to cover their daily needs. People in the other villages continued using regular salt.

During the study, 3,000 people had a stroke. Researchers found that the stroke risk of those using the salt substitute was reduced by 14 per cent. Their wider risk of stroke, heart attack or other major cardiac and circulatory events was reduced by 13 per cent, and death from any cause by 12 per cent.

Lead investigator, Professor Bruce Neal, said that if the low-cost salt substitute was widely adopted, it could prevent millions of deaths globally. He said that, while patients with serious kidney disease should avoid both regular salt and salt substitutes: “We saw no indication of any harm from the added potassium in the salt substitute."

The researchers said the results confirmed an earlier study which suggested 400,000 premature deaths might be prevented a year in China if there was a national switch to salt substitute.

The researchers made the following recommendations:

• salt manufacturers and retailers worldwide should switch to producing and marketing salt substitute
• governments worldwide should design policies to promote salt substitute and discourage regular salt use
• consumers worldwide should cook, season and preserve foods with salt substitute, not regular salt.

How good was the research?

A major strength of the study was the large number of people taking part over a long period of time.

While the study looked at an important health issue, it’s hard to know whether results would be similar in different locations, such the UK, where the diet is very different to that of people in rural China.

Chinese villagers consume less processed food and are more likely to cook from scratch, meaning much of the salt they eat is added by the cook. In the UK, with a diet higher in processed foods that already contain high levels of salt, it is harder to control the amount of salt we eat.

The study also followed a very specific group of people with similar health problems. It’s unclear whether similar results would be seen in younger individuals or those with blood pressure in the normal, healthy range.

The BHF view

Victoria Taylor, Senior Dietitian at the British Heart Foundation, said:

“This research is a helpful reminder to cut the amount of salt we have in our diets and to look for alternatives. However, it’s not necessarily applicable to the UK population. The group of people studied were from rural China, and so diets, lifestyle, and salt intakes are probably different. They also only included people with a previous history of stroke or people who were 60 years or older and had poorly-controlled high blood pressure.

Low salt alternatives have less sodium than regular salt, so they can be useful for eating less sodium, but they won’t help you kick the habit of salty foods. It’s still better to eat less of it. The salt alternatives contain potassium which aren’t suitable for some people with existing health conditions, therefore it’s best to check with your doctor before using them. Why not try using other flavourings for your food such as herbs, spices, black pepper, chilli or lemon.”

How accurate was the media coverage? 

The story was covered by The Times, The Daily Mail, The Evening Standard and The Independent.

Coverage was broadly accurate and balanced and gave the key details of the study, along with its findings. All the newspapers chose to report similar facts and quotes from The George Institute for Global Health’s press release.

The only difference between articles was that, while most reported that the use of salt substitute could prevent thousands of strokes and heart attacks, The Independent in its headline stated that it “would prevent millions of deaths”. Taken alone this could be misleading. The article by The Independent accurately reported on the study. But it didn’t highlight the difference between the diet of rural Chinese people compared to UK citizens and how this might lead to less significant decreases in heart attacks and strokes.

All the newspaper coverage mentioned the importance of reducing salt in the diet and the fact that the food industry and individuals need to look at using a substitute as well as reducing the quantity of normal or substitute salt in their food.