Customers ordering hot drinks with non-dairy milks, such as oat or almond milk, are unknowingly consuming excessive sugar, according to new research.
Action on Sugar, a charity based at Queen Mary University London, says the perception that vegan options are healthier, and the lack of labelling on products, means people are drinking more sugar than they are aware of.
The charity analysed sugar and calorie content of the largest available sizes of 124 hot chocolates and 79 seasonal lattes from high street coffee chains across the UK.
It used information from the websites of Caffe Nero, Starbucks, Costa, KFC, Greggs, McDonalds, EAT, Leon and Pret, looking at data for both cow’s milk drinks and milk alternatives.
It found certain seasonal beverages contain almost as much sugar as three cans of Coca-Cola, with almost all of the largest available size products receiving a red traffic light for total sugars.
The study found Starbucks' venti-size Signature Caramel Hot Chocolate with whipped cream, using oat milk, had the highest sugar content of the hot chocolates surveyed.
It contained more than 23 teaspoons, or 93.7g, of sugar and 758 calories - equivalent to four white chocolate and strawberry muffins from Tesco.
The seasonal latte with the most sugar is the Starbucks Gingerbread Latte with oat milk in venti size, containing more than 14 teaspoons of sugar and 523 calories.
A venti Starbucks latte with oat milk had more than seven teaspoons of sugar and 350 calories but a venti Starbucks latte with almond milk contained just three teaspoons and 121 calories.
Katharine Jenner, campaign director at Action on Sugar, said: "Customers looking for dairy alternatives could be shocked to learn that many coffee shops and cafes use pre-sweetened alternative milks as the nutrition information is often very difficult to find - with information only available on websites or not at all."
Nearly a third (27 per cent) of products directly comparable with a similar study in 2016 had actually increased their sugar content.
A regular vanilla latte from KFC had 19g of sugar in 2016 but now contains 26g, though a mocha from the outlet has reduced from 45.1g of sugar to 21g over the same period.
Costa has decreased the sugar content of some products by more than 50 per cent since 2016.
Registered nutritionist Holly Gabriel, of Action on Sugar, said: "It is shocking that so many high street coffee chains are wilfully putting their customers' health at risk despite Public Health England (PHE) setting sugar reduction targets for sugary milk drinks in 2018.
"Coffee shops and cafes need to take much greater steps to reduce the levels of sugar and portion sizes, promote lower sugar alternatives and stop pushing indulgent extras at the till."
Professor Graham MacGregor, chairman of Action on Sugar, said it is "vital" that the next government fully commits to the target of halving childhood obesity by 2030.
Starbucks told The Independent: "All our drinks can be customized, such as asking for our smallest size; short, requesting skimmed milk and less or no whipped cream.
"To help make it easier for customers to make informed choices, nutritional information is also available in-store, on our mobile app and online. We are committed to reducing sugar in all our beverages and since 2015, we’ve delivered a 9% reduction in the sugar content of our Gingerbread and core syrup range of vanilla, caramel and hazelnut.”