By Annabel RackhamBBC News
Getty ImagesThe current, "traffic-light" system may provide insufficient information for consumersLabelling foods as ultra-processed might not be so helpful for consumers who want to know how healthy a product is, UK experts say.
Currently, packs must show whether a food item is high in fat, salt and sugar but not how processed it is.
Scientists who analysed different products say it is too simplistic to brand all ultra-processed foods (UPFs) as very bad.
Technically, sliced bread is ultra-processed, for example.
Though many UPFs are clearly unhealthy, some could fall into the "healthy" green category of the "traffic-light" system.
This was the case for meat-alternative products, the University College London team said, and some people may be unaware what they were buying was ultra-processed.
Five ingredients
UPFs have been linked to obesity and heart disease.
They are defined by how they are made and what they contain.
They often have more than five ingredients, with examples including cakes, biscuits and yoghurts.
At the other end of the scale are unprocessed foods such as fruits, vegetables and fresh meat - and in the middle, processed foods such as cheeses and tinned products.
Getty ImagesUltra-processed food items contain more than five ingredients and are often high in fat, saturated fat, sugar and saltOf nearly 3,000 food and drink items popular in the UK the researchers looked at:
- 55% were ultra-processed and labelled red, containing significantly more fat, saturated fat, sugar, salt and energy per 100g than the minimally or unprocessed, which tended to be labelled green
- But some UPFs were green and some minimally processed, such as nuts, seeds and whole milk, red
Getty ImagesThe researchers looked at nearly 3,000 food items popular in the UKUCL senior research fellow and weight-management specialist Dr Adrian Brown told BBC News he had looked at a "meat alternative", for example.
"Generally, it can be considered highly processed - but if you look at front-of-package labelling for energy, fat, saturated fat and sugar, they're all green, which would be considered healthy," he said.
And there was too little research into the effect of UPFs on general health.
"There's a bit of a grey area [with UPFs] as, at this present time, we only have association data between ultra-processed food and health outcomes such as diabetes and heart disease," Dr Brown said.
Getty ImagesMany meat-free alternatives appear healthy under the traffic-light systemThe government's Scientific Advisory Committee on Nutrition (SACN) also described "uncertainties around the quality of evidence available".
Dr Brown's team at UCL have now begun a trial to see how healthy a UFP-only diet can be, compared with a minimally processed one, and whether guidance should be given to consumers.
"We're putting people on an eight-week diet which meets the government's recommendations for salt, fat, sugar and energy - what is considered healthy - and we're comparing the outcomes of them, related to weight and other changes in terms of health as well," he said.
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