Double D lollies, which are sold at Countdown, New World and the Warehouse, are sugar-free and sweetened with a sugar alcohol called maltitol, known for its potential to send people running straight to the toilet.
"Maltitol will typically give people tummy cramps, excess gas, and bloating. Some will get away with these side effects, whereas others - especially if they eat a bit more of it - will have what can only be described as explosive diarrhoea," said Hannah Noble, who runs the Keto New Zealand Facebook page.
The lollies can be popular with many on low- or zero-sugar diets such as keto, but most people find their bodies reacting badly not long after eating the lollies.
"Double D lollies have more maltitol than other things that contain maltitol, and also often contain other sugar alcohols which has a similar effect but it takes a lot more of it for it to happen. In combination, it seems to make it easier to happen with these lollies," Noble said.
"One person might have diarrhoea with three lollies whereas someone else might have it with a bag and others have gotten away without it.
"Some Double D lollies don't have maltitol. It is the soft and chewy ones that have it."
Dietician Dr Amy Liu said maltitol had about 75-90 per cent of the sweetness of sucrose, and was about half the calories.
"Maltitol attracts water from the intestinal wall via the osmotic effect, so can have a laxative effect and stomach upset on the body," she said.
"As maltitol is incompletely digested, sugar alcohol can lead to gas, bloating and diarrhoea, if large amounts are consumed."
She believed the reason some people reported a greater or more immediate physical reaction to Double D lollies compared to other foods containing maltitol was that the dose would be greater in a solid food compared to a liquid food.
The lollies bear a warning on the package stating excessive consumption may cause a laxative effect. But because of different bodily reactions, excessive consumption for some people can be as little as two or three lollies.
A Food Standards Australia and New Zealand (FSANZ) spokeswoman said maltitol and maltitol syrup (965) were permitted as food additives in New Zealand.
"Any food containing maltitol or maltitol syrup must bear an advisory statement to the effect that excess consumption of the food may have a laxative effect."
When asked whether there should be more done to warn customers about the sometimes violent effect of the lollies, Countdown and New World spokespeople declined to comment.
Warehouse Group chief product officer Tania Benyon said they only stocked food items that complied with FSANZ.
"All food items we sell comply with [the] requirements".
Double D has been contacted for comment.
