A Japanese drugmaker said Tuesday it is investigating one death from kidney dysfunction potentially linked to health supplements recalled last week by the firm.

It comes a day after the company said it was aware of 26 cases of people being hospitalised in relation to the prescription-free tablets.

Kobayashi Pharmaceutical, which sells over-the-counter drugs and dietary supplements, has received an additional 50 unconfirmed reports of hospitalisations as of Tuesday morning, a spokeswoman told AFP.

The three recalled brands -- "beni koji choleste help" and two similarly named supplements -- contain an ingredient called red yeast rice, or "beni koji".

Made by fermenting rice, it is supposed to lower levels of bad cholesterol.

The person who died had regularly purchased one of the recently recalled products over the course of nearly three years, the Osaka-based drugmaker said.

"We're now aware of one instance where there is a potential causal link between a death and our product," the company said in a statement.

"We are currently investigating the link, and what happened," it added, offering its "deepest apologies".

Kobayashi Pharmaceutical says it has also supplied red yeast rice to around 50 other firms in Japan and two in Taiwan.

Health Minister Keizo Takemi told reporters that the ministry "will cooperate with Osaka city to investigate the cause... and prevent further health-related damage".

The company voluntarily recalled its products on Friday following customer complaints about kidney problems.

It said on Monday that it had not reached a conclusion on a link between the health problems and its supplements.

However, analysis had found a possibility that the products contained "ingredients we had not intended to include", it said.

Its analysis did not find any citrinin produced by red yeast rice, which is toxic and can damage the kidneys.

Japanese media reports said company executives would visit the victim's family on Tuesday.