A Japanese drugmaker said on Friday it is investigating five deaths potentially linked to dietary supplements meant to lower cholesterol and apologised for the "anxiety and fear" it had caused.

Kobayashi Pharmaceutical has recalled three brands of over-the-counter tablets after customers reported kidney problems.

The firm said it was trying to establish if the products containing red yeast rice, or "beni koji", had caused five deaths and 114 hospitalisations.

Medical studies say red yeast rice can lower cholesterol but also warn of a risk of organ damage depending on the ingredient's chemical make-up.

The growing crisis has made headlines in Japan, with Prime Minister Fumio Kishida pledging to consider "all possible measures" to prevent similar incidents if the deaths were caused by the products.

"I apologise deeply for the great anxiety and fear we have caused," company president Akihiro Kobayashi told a news conference on Friday.

He said the company would "devote all our energies" to investigating the matter.

Kobayashi Pharmaceutical, which voluntarily recalled "Beni Koji Choleste Help" and two other tablet brands a week ago, supplies red yeast rice to around 50 other firms in Japan and two in Taiwan.

Some of those companies have preventively recalled food products containing the ingredient, including a rose-coloured sake and salad dressing.

Kobayashi Pharmaceutical said in a statement earlier Friday it had been informed of the death of a fifth customer who had been taking Beni Koji Choleste Help and developed a kidney condition.

"We are in the process of confirming the facts and causal relationship," the statement said.

Taiwanese companies have preventively recalled 154 products containing red yeast rice in the wake of the scare, the island's health authorities said.

A woman in her 70s in Taiwan has also reportedly developed kidney failure after taking Kobayashi's supplements for several years.

Kobayashi officials acknowledged that the recalled supplements contained puberulic acid, derived from blue mould, after the health ministry said the substance might have been in the red yeast rice products.

But the company said the acid has not been confirmed as the cause of the illnesses, since its toxicity has not yet been examined.

Kobayashi's red yeast rice supplements are regulated under a system created in 2015 under former premier Shinzo Abe.

Some watchdogs have reportedly expressed concerns that the regulation of these products is not sufficiently stringent and that they do not always have the advertised effects.

Top government spokesman Yoshimasa Hayashi on Friday instructed ministers to review the regulatory system and compile a report by the end of May, local media reported.