Children’s yoghurts are packed with sugar, experts have found, warning that manufacturers and retailers need to do more to tackle the problem.

Although yoghurt has long been considered a healthy food, experts warn that many of the products sold in supermarkets could contribute to child obesity, tooth decay and other health problems due to their high sugar content.

To be classed as “low sugar” and earn a green label on their packaging, food products must contain a maximum of 5g of sugar per 100g. But a new study, which looked at almost 900 yoghurt products available on British supermarket shelves in autumn 2016, has revealed that those aimed at children had on average more than twice this level.

In 2016 Public Health England set the food industry a target to cut sugar in various food product categories by 5% in the first year and 20% by 2020. PHE revealed in May that the industry had largely missed the targets, although the yoghurts category did achieve a 6% reduction.

However, despite the progress, the researchers behind the latest study say there is a long way to go.

“If we are talking about children’s products, so 10.8 [g of sugar per 100g], then 5% less we are talking 10.2g/100g … there is definite room for the industry to do more, and I know that they are doing it, but it is not enough,” said Dr Bernadette Moore, first author of the research from the University of Leeds, adding that she was “shocked and surprised” by the levels of sugar the study revealed.

The researchers note that yoghurt is an important source of nutrients including calcium, protein and vitamin B12, and is linked to digestive benefits. But they warn that what many consider a healthy food could also play a part in various health problems due to its sugar content.

Moore recommends parents of young children introduce them to natural yoghurt with fruit mashed up, and let older children add nuts, granola or other healthy items into the mix.

But, she added, “If you are deciding between a Coca-Cola, a Snickers bar, those little icicle biscuits that children love at parties, and a yoghurt, then the yoghurt is the best of those choices.”

Writing in the journal BMJ Open, Moore and colleagues describe how they looked at nutritional data for 898 products by searching the online grocery websites of five major UK supermarkets.

The team sorted the products into eight groups including desserts, organic yoghurt, natural or Greek yoghurt, dairy alternatives and yoghurts aimed at children, including fromage frais.

The results reveal that the mid-value for almost all categories was far higher than the “low-sugar” benchmark, with a median of 16.4g of sugar per 100g for desserts and 10.8g/100g for children’s products. Only 2% of children’s products would have earned the green label indicating low sugar. However natural or Greek yoghurt hit the mark, with a median of 5g of sugar per 100g.

Moore noted that the values only reflect the total sugar content, as labels do not separate naturally occurring sugars such as lactose from added sugars, but said the research suggests approximately 5g of sugar per 100g can be thought of as largely being lactose, with levels above that coming from added sugar.

The team also note that many products marketed as being good for cholesterol were found to be high in sugar while the “health halo” of organic yoghurts might have slipped, with the category found to have the second highest median sugar content after “dairy desserts” with about 13g of sugar per 100g.

Dr Alison Tedstone, chief nutritionist at Public Health England, said that the food industry is a critical player in reducing how much sugar the public consumes.

“Based on more recent data than in this study, we have seen positive steps – yoghurt and fromage frais was the only category to exceed the first year sugar reduction ambition of 5% – and hope to see further progress when we publish our next report in 2019,” she said.

Caroline Cerny of the Obesity Health Alliance stressed that overconsumption of sugar is one of the factors driving the high rates of obesity in the UK, but acknowledged that sugar levels in yoghurts are falling.

“However, as this research shows, there is much more manufacturers can do to reduce the sugar added to their products, particularly the ones aimed at children.”