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 United Kingdom supermarkets.
"Items labelled organic are often thought of as the "healthiest" option, but they may be an unrecognised source of added sugars in many people's diet".
Only natural/Greek yogurts met the UK's criteria for "low-sugar".
Yogurt is often regarded as a healthy snack but a new study finds that most yogurts on store shelves are chock-full of sugar.
They contained an average of 10.8g per 100g - the equivalent of more than two sugar cubes.
The researchers wrote, "While yogurt may be less of a concern than soft drinks and fruit juices, the chief sources of free sugars in both children and adults" diets, what is worrisome is that yogurt, as a perceived "healthy food, ' may be an unrecognised source of free/added sugars in the diet".
The only exception was with natural, Greek and "Greek-style" yogurts. In these categories, average sugars ranged from 10.8g per 100g in children's products to 13.1g per 100g in organic products. Yogurt is particularly recommended for babies and children and, in fact, those up to the age of three years in the United Kingdom eat more yogurt than any other age group. "Many portion sizes for children's yogurts were identical to adult portion sizes".
The average sugar content of products in most categories was well above the low sugar threshold.
Study co-author Annabelle Horti, who conducted this research while at the Leeds" School of Food and Nutrition, said: "Changing the public desire for "sweeter' yogurts may be a real challenge when it comes to reducing its sugar content". Yogurt is one of the products identified and highlighted for a 20% reduction of sugar by 2020. This may be why these products had higher amounts of added sugar to offset the sourness.
Moore thinks that if individuals know more about sugar in yogurt, they can make different decisions for themselves and their families. 'Yogurts contain natural sugar from the milk, as well as any fruit that's included'.
Natural sugar is the sugar naturally present in a food - in yoghurt (and other dairy products) it's mostly a type of sugar called lactose.