London (CNN)Most yogurts have deceptively high levels of sugar, with organic yogurts among the worst offenders, a new study warned.
Researchers analyzed more than 900 yogurt brands found in UK supermarkets and found that only 9% can be classed as low in sugar -- containing less than five grams of sugar per 100 grams -- while just 2% of children's yogurts are low in sugar.
The study also warned of the "health halo" effect that leads consumers to automatically assume that organic products are healthier, despite this category of yogurt being the most sugary.
Organic yogurts contained an average of 13.1 grams of sugar per 100 grams, which is roughly equivalent to three sugar cubes, while children's yogurts averaged 10.8 grams. Greek and natural yogurts were the least sugary varieties, with an average of five grams per 100 grams.
Yoghurts marked as "desserts" contained the most sugar, with an average of 16.4 grams per 100 grams.
"While yogurt may be less of a concern than soft drinks and fruit juices, the chief sources of free sugars in both children and adult's diets, what is worrisome is that yogurt, as a perceived 'healthy food', may be an unrecognized source of free/added sugars," the authors wrote.