The chairman and president of a major Japanese dietary supplement maker is to resign, as the company probes up to 80 deaths potentially linked to dietary supplements meant to lower cholesterol.

Kobayashi Pharmaceutical, a household name in Japan, is at the centre of heath fears linked to its over-the-counter tablets containing red yeast rice, which is fermented with a mould culture.

The company’s board released a damning external report on Tuesday that said the firm had failed to prioritise consumer safety and acted with an “insufficient sense of urgency”. The report by a team of external lawyers said the company began to receive reports of kidney problems from doctors in mid-January and early February.

Red yeast rice or “beni koji” has been used in food, alcoholic drinks and folk medicine for centuries around east Asia.

Medical studies say it can improve cholesterol levels but also warn of a risk of organ damage depending on the ingredient’s chemical makeup.

Kobayashi Pharmaceutical said president Akihiro Kobayashi and chairman Kazumasa Kobayashi were leaving their posts. Both men belong to the firm’s founding family.

The decision was made “to clarify executive responsibility over a series of actions by our company related to the ‘beni koji’ issue”, it said in a statement.

The scandal erupted in March when the company recalled three brands of dietary supplements after customers complained of kidney problems.

It later said it had detected a potentially toxic acid produced by the mould at one of its factories, and the government inspected the firm’s facilities.

Then last month, the company said it was probing a total of 80 deaths possibly connected to its pills, and investigating whether organs other than kidneys were harmed.

At the time, the government called Kobayashi Pharmaceutical’s delay in reporting the number of cases under investigation “extremely regrettable”.

The lawyers said in Tuesday’s report: “Kobayashi Pharmaceutical had never before received multiple reports of serious cases from doctors in such a short period of time.

“Despite this, the company did not immediately consider disclosure to consumers, acting with an insufficient sense of urgency.”

The company should have recalled the products right away and reported the incident, but it decided to do so only after conducting internal probes, the lawyers alleged.

Kobayashi Pharmaceutical’s new president is Satoshi Yamane, previously head of sustainability policy, the company said.

Outgoing president Akihiro Kobayashi, who has expressed his intention to take responsibility for any harm caused, will remain in an executive role to manage compensation-related matters, it added.