Photo/Illutration Masanori Abe, an internal medicine doctor at Nihon University Itabashi Hospital (Asahi Shimbun file photo)

A nephrologist at a Tokyo hospital treated three patients over the past four months who had one thing in common—they all took a supplement containing benikoji, which is suspected of causing kidney and other health-related problems. 

Masanori Abe, an internal medicine doctor specializing in kidney problems, high blood pressure and internal secretion at Nihon University Itabashi Hospital, treated three female patients between November and February who were hospitalized.

One was in her 70s and the other two were in their 50s.

They all experienced urinary problems and tests found an abnormally high level of creatinine in the blood, which measures kidney functioning. The women also tested positive for blood and protein in their urine.

Abe spoke with The Asahi Shimbun on March 28. He called on Kobayashi Pharmaceutical Co., which manufactured the supplement, to pinpoint the element causing the health problems and called on those taking it to undergo tests at medical institutions.

“Kidney illnesses have few noticeable symptoms so it is difficult to become aware of a problem at an early stage,” Abe said. “People who have taken the supplement or are experiencing abnormalities with their urine should visit a medical institution.”

The three women Abe treated had no underlying health problems and were not taking any medications when they were hospitalized.

But all three began ingesting Kobayashi Phamaceutical’s “Benikoji coleste-help” from around spring 2023.

Testing at the Itabashi hospital led to all three women being diagnosed with inflammation of kidney tissue. The disease is normally caused by taking pain medicine and if left untreated can lead to kidney failure.

Patients with a pre-existing heart condition are in danger of dying if they are also diagnosed with kidney tissue inflammation.

The three women were treated with medicine and were hospitalized between one to several weeks. All have since improved and have left the hospital, but Abe said they will still need to take medicine for about six to 12 months.

“The only thing they had in common was the supplement,” Abe said. “Something in that supplement likely triggered their illnesses.”

The two women in their 50s still had some of the supplement left at home. A blood test for allergic reactions was conducted using the remaining supplement. Only one of the women had an allergic reaction.

On Feb. 1, after treating those two women, Abe, through a hospital colleague, contacted Kobayashi Pharmaceutical. A company official said they had no information of other similar cases.

Abe again contacted Kobayashi Pharmaceutical after treating the third woman.

A company official who visited the hospital on Feb. 29 was given a thorough explanation of the symptoms displayed by the three women.

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