Trendy vegan yoghurts can contain more sugar than dairy ones – even if they are considered to be healthier.
Scientists analysed the sugar content of 893 yoghurts and dessert products sold in British supermarkets, 67 of which were vegan.
Dozens of yoghurts that contained milk were found to have less sugar than some of the worst offending dairy-free alternatives.
The study, which comes while many will be attempting 'Veganuary', revealed Coconut Collaborative Little Choc Pots contained 20 per cent sugar - 20g per 100g.
Asda's Free From Chocolate Mousse is 16 per cent sugar, meaning a 90g pot contains almost four teaspoons of sugar in a small pot.
In comparison, natural Greek yoghurt contains as little as three per cent sugar in a 100g serving.
Because vegan products don't contain milk, which has naturally occurring sugars, manufacturers often have to flavour their yoghurts with syrups and fruit purees.
The market for dairy alternatives has boomed in recent years and doubled since 2016, the study by the University of Leeds found.
But consumers should be wary that plant-based products may still be high in 'free sugars' - which are not naturally occurring and are added for flavour - even if marketing ploys give them a 'health halo'.
Coconut Collaborative Little Choc Pots are a 'dessert' product made of a coconut cream instead of milk. They contain 20g of sugar per 100g, researchers at University of Leeds found. It was one the most sugary product of the 67 studied by the academics
The second highest sugar content was found in the chocolate mousses from Asda's Free From range, which had 16g of sugar per 100g
Koko Dairy Free Peach and Passion Fruit Yogurt Alternative contains 12.5g of sugar per 100g. It's sold in 125g pots, therefore containing around 15.6g of sugar per serving
Dr Bernadette Moore, first author of the study, said: 'Movements such as Veganuary may encourage people to reconsider their eating habits.
'But it's important people are aware that dairy alternatives may be an unrecognised source of added sugar to their diet.
The University of Leeds studied 893 yoghurts and dessert products sold in British supermarkets, 67 of which were vegan.
The following were found to have the highest sugar content:
Coconut Collaborative Little Choc Pots: 20g/100g. Sold in 45g pots = 9g sugar per serving.
Asda Free From Chocolate Mousse: 16g/100g. Sold in 90g pots = 14g sugar per serving.
Tesco Free From Mango Yogurt Alternative: 12.5g/100g. Sold in 100g pots = 12.5g sugar per serving.
Koko Dairy Free Peach and Passion Fruit Yogurt Alternative: 12.5g/100g. Sold in 125g pots = 16g sugar per serving.
Freaks of Nature Mango and Passion Fruit Posset: 11.8g/100g. Sold in 90g pot = 11g sugar per serving.
Alpro, Caramel Soya Dessert: 10.8g/100g. Sold in 125g pots = 14g sugar per serving.
'Because dairy alternatives do not have lactose, which is a naturally-occurring sugar, the total sugar content comes entirely from added sweeteners. Generally added sugars are considered to be worse for teeth and health.
'Given the wide range of sugar levels across these products, people making a switch to a vegan-friendly yogurt should scrutinise product ingredients carefully.'
Many people may be duped into thinking the growing number of fashionable vegan products are healthier for them.
But Dr Moore said: 'The question of whether plant-based yogurts provide the same nutritional and health benefits as those made from cow's milk is currently under investigation.'
Researchers surveyed products by searching the websites of Tesco, Asda, Waitrose, Morrisons and Sainsbury's. Those which came up when the word 'yoghurt' was searched for were analysed, which included desserts, fromage frais and yoghurt drinks.
The aim was to see if companies had reduced sugar content in yoghurts between 2016 and 2019, after being encouraged to do so by the Government.
A 'high sugar' product is one which contains more than 22.5g of sugars per 100g, and a 'low sugar' product is 5g or less per 100g, the NHS says.
Freaks of Nature, a company which boasts about using 'natural' ingredients, sells a Mango and Passion Fruit Posset with 11.8g per 100g. Each pot is around 90g
Consumers should be wary that plant-based products may still be high in 'free sugars' - which are not naturally occurring and added for flavour - even if marketing ploys give them a 'health halo', researchers said amid a rising interest in veganism
Overall, 27 per cent of almond, soya and coconut based alternatives had more than 10g of total sugar per 100g.
The findings also show 54 per cent of all products are tipping the 10g barrier, and children's yoghurts, flavoured, fruit and organic yoghurts are still the most sugary on the high street.
The Coconut Collaborative's Little Choc Pots had the most sugar per