Toddlers in the UK obtain almost half of their calories from ultra-processed foods, rising to 59% by the age of seven, according to the largest study of its kind.

The first comprehensive review of dietary intake at such an early age comes amid rapidly rising global consumption of UPF such as cereals, protein bars, fizzy drinks, ready meals and fast food. The findings were published in the European Journal of Nutrition.

Researchers from UCL in London used data from the Gemini twin cohort study and the Nova classification to assess the food consumed. UPFs were typically industrially produced and contained ingredients not used or very rarely used in home cooking, such as emulsifiers, colourings and sweeteners, they said.

Toddlers in the UK obtain 47% of their calories from UPFs, and this grew to 59% by the age of seven, the researchers said. The study looked at data from 2,591 children born in the UK in 2007 and 2008 whose parents recorded what their children ate and drank over three days.

The most common UPFs consumed by toddlers – who were 21 months old when their parents recorded their diets – were flavoured yoghurts and wholegrain breakfast cereals, products typically seen as healthy. By the age of seven, the most common UPFs were sweet cereals and puddings.

There were several limitations of the study, including that people of white ethnicity and a higher socioeconomic status were over-represented in their sample compared with the UK population. The research also relied on data from some children born 17 years ago.

However, the study’s senior author, Prof Clare Llewellyn of UCL, said there were no other contemporary datasets that had measured dietary intake in great detail at this early age in a large, representative sample, with repeated measures in the same children.

“It is extremely unlikely that children now consume less UPFs than in 2008/9 or 2014, or that dietary patterns of children have changed markedly,” she said. “So, these are likely to be conservative estimates of UPF consumption.”

She added: “Eating patterns in the early years are important, as they help set habits that can persist through childhood and into adulthood.

“This was reflected in our findings, with 21-month-olds who ate more ultra-processed foods also likely to be higher consumers of ultra-processed foods at the age of seven.”

The UCL team called for policies to “redress the balance of children’s diets toward a lower proportion of UPF, such as adding warning labels to products, inclusive school food policies and subsidies on fresh and minimally processed food”.

Lead author Dr Rana Conway, also of UCL, said: “It’s not easy to feed children healthily in our current food environment. Highly processed foods are often cheaper than the foods parents would like to give their children, such as fresh fruit and vegetables.

“Also, despite labels suggesting they’re a healthy choice, ultra-processed foods marketed for children often contain too much sugar and salt. This makes it harder for parents to make healthy choices.”