The company also uploaded an announcement from the National Food Quality Supervision and Inspection Center.

"Long-term regular and unscheduled sample checks showed that Red Bull products are in accordance with the standards it has claimed, and have never been found to contain unregistered substances," reads the announcement dated Saturday.

The Harbin food and drug administration on Saturday put a statement on its website, which said that Red Bull beverages were approved as a health food by the Ministry of Health in 1997.

The statement said that government records show that sodium benzoate, sodium citrate, carmine pigment and tartrazine - which are said to have been listed among the food additives on the product bottles, though they are not registered with government agencies - are included in its ingredients.

But records on the website of the State Food and Drug Administration did not provide the same information. None of the four additives are listed among the primary ingredients of the beverage, a China Daily reporter found.

Regardless of whether these substances are registered, food experts said some might have been abused.

"The use of sodium benzoate in the product, a beverage for special purposes, doesn't meet the requirements for using food additives," said Yu Yuqin, a senior engineer from a Shanghai food industry institute.

The national standards for food additives implemented in 2011 indicate that the preservative can be used - in limited amounts - in tea, coffee and herbal drinks. Vitamin drinks are excluded.

Some other additives listed on the product's bottles might also be misused.

Sodium citrate is only allowed in baby formula and infant food supplements as an acidity regulator, and caffeine is only permitted in cola-type carbonated drinks, according to the standards.

People with cardiovascular diseases must be cautious about caffeine, which is a stimulant, said doctors.

"Long-term intake will affect kidney functions and calcium retention," said Gu Zhongyi, a dietitian at the Beijing Friendship Hospital.

Chen Xu, a 27-year-old Shanghai resident, said he was surprised that a product launched 15 years ago had been faulty for so long.

"I think government watchdogs should have guarded the pass. Now they must put the products under scrutiny, and give a clear answer to the public," he said.