The Consumer Council on Monday urged the government to regulate an increasingly popular food supplement - probiotics - after finding that many are not properly labelled.

Probiotics are often marketed as "good" bacteria because they help keep the gut healthy.

The watchdog studied 40 brands of probiotics and said 25 of them did not correctly state the type of bacteria, the amount of bacteria or, in the worst cases, no information at all.

Two samples contained a bacterium, Enterococcus faecalis, which is not recommended for human consumption by the World Health Organisation because of safety concerns.

Council chief executive Gilly Wong said it was undesirable that so many products didn't have the right information on their labels.

"If the information is not clear, you don't know what you're taking, you don't know your intake quantity," she said.

"[The products have] so many claims saying it's good for your health, for immunity, your allergy, eczerma et cetera, but for certain claims it's not scientifically proven."

Ten of the products claimed to be suitable for newborn babies.

But Wong said babies don't have fully developed gastrointestinal tracts and it's not recommended that they take probiotics.

The council noted that US authorities reported that an infant died last year after consuming a probiotic formula.