Coca-Cola has quietly reduced the sugar content of some of its biggest brands, including Sprite, Fanta and Dr Pepper, without affecting sales, the company’s chief executive has said.

The fizzy drinks giant has made a number of reductions in sugar content over the last four years, including a 30% cut in Fanta two weeks ago, according to the Times. There were similar reductions to Sprite and Dr Pepper in 2013 and 2014.

Sweeteners have been added to try to maintain the same taste. For example, in Sprite the company is adding stevia, a plant extract, while in Fanta the company is using acesulfame, an artificial sweetener.

Fanta now contains less than half the sugar of Coca-Cola, the company’s eponymous and most popular brand, at 4.6 grams per 100ml compared with 10.8g.

The chief executive, James Quincey, said the changes had not significantly hit sales. He told Bloomberg Businessweek: “We took some of the calories out of Sprite and consumers like Sprite now as much as they did before. Then we took 30% of the calories out of Fanta to see what would happen. Again, sales seem to be continuing fine.”

A sugar tax is due to come into force in the UK next year affecting heavily sugared fizzy drinks. Under the new rules, producers or importers of soft drinks will have to pay a tax of 18p per litre on drinks containing five grams or more of sugar per 100ml and 24p per litre more if their products contain eight grams or more per 100ml. The Treasury expects the levy to raise £520m a year.

Quincey suggested the size of bottles and cans containing Coca-Cola products may be reduced to help cut sugar consumption.

“If people are going to drink everything that’s in front of them, well, when they’ve got a smaller package, they’ll have less. That’s the sort of thing moms like for kids,” he said.