Iced coffee drinks from high street chains can contain more sugar than a Mars bar or can of Coca-Cola, a survey has found.

Which? compared frappes and frappuccinos from Caffe Nero, Costa and Starbucks to find many had “exceptionally high” amounts of sugar.

One of the unhealthiest options was a Starbucks caramel frappuccino with semi-skimmed milk containing 48.5g of sugar, or 12 teaspoons’ worth.

NHS health advice suggests adults consume a maximum of 30g of sugar per day, or around seven teaspoons.

A Caffe Nero Belgian chocolate and hazelnut frappe creme contained 44.5g of sugar, equivalent to 11 teaspoons.

At Costa, a chocolate fudge brownie frappe mocha with oat milk included 42.6g of sugar, or 10.5 teaspoons.

A 51g Mars bar contains 31g of sugar, or 7.5 teaspoons, while a 330ml can of Coca-Cola contains 35g of sugar, or around eight and a half teaspoons.

Even plain coffee flavour frappes and frappuccinos were found to contain “relatively high” amounts of sugar.

A Costa Coffee frappe with skimmed milk contained 21.3g of sugar, Which? found.

Coffee stock
Coffee beans in a mug (John Walton/PA)

While the calorie content of the drinks must be displayed in stores, the sugar content does not, which could leave consumers at risk of unwittingly exceeding the maximum recommended daily intake of free sugars, the watchdog said.

Dairy-based drinks derive some “locked in” sugar from lactose, but all the drinks also contained high amounts of “free sugars”, those that have been added and contained in syrups, honey and fruit juice.

Health advice is to limit consumption of these sugars due to their potential to contribute to weight gain and tooth damage.

Which? suggested consumers wishing to cut their sugar intake switch to iced versions of a standard coffee instead.

The Government introduced a Soft Drinks Industry Levy (SDIL) in 2018, known as the “sugar tax”, in an attempt to cut unhealthy levels of consumption.

However, some drinks are exempt from the tax, including fruit juices and drinks made on-site and served in open cups.

Syrups, often used in frappes, are also exempt.

Which? nutritionist Shefalee Loth said: “Our analysis of sugar content in iced coffee blends shows people could unwittingly be consuming much more sugar than they realise, with potentially damaging implications for their health.

“High street chains need to take more responsibility and reduce the excessive sugar content of some of their drinks to protect people’s health.

“When buying an iced drink, there are alternative, healthier options to choose, such as a standard iced coffee, which contains far less sugar.”

A Starbucks spokeswoman said: “We are committed to helping customers make informed and improved choices that work for them, offering a range of customisation options such as choosing our smallest size (Tall) and our oat dairy alternative with no added sugar.

“Sugar content for an Iced Latte with Semi Skimmed Milk, one of our most popular beverages, starts from 8.7g for a Tall size.

Customers can find all nutritional information available on our mobile app, online and our menu boards.”

Caffe Nero said its Belgian chocolate and hazelnut frappe creme was a “treat” and accounted for less than 5% of its sales of summer drinks, while “coffee over ice” drinks, which contained less than 8g of sugar, accounted for 50% of summer drink sales.

The chain added that its iced latte, its highest seller, contained no added sugar.

A Costa Coffee spokeswoman said: “We are proud to offer a balanced range of drinks which also includes, as part of our summer menu, a fruity range of refreshers which all contain less than 40 calories and two teaspoons of added sugar per serving.

“We only offer our limited-edition seasonal drinks, including our summer range of frappes, in small and medium sizes.

“All drinks can also be customised to reduce the calorie or sugar content, including requesting skimmed milk and removing toppings, or downsizing to a smaller cup size.”