Photo/Illutration Yoshitaka Isaka, professor of nephrology at Osaka University, reports the latest findings on health problems linked to benikoji red yeast supplements on June 30 in Yokohama. (Shuichi Doi)

YOKOHAMA--Months after they had stopped taking Kobayashi Pharmaceutical Co.’s “benikoji” dietary supplements, 85 percent of patients still showed signs of kidney damage linked to the products, a study found.

The findings were presented at a symposium held here on June 30 by the Japanese Society of Nephrology. The latest report is an update to the society’s April study, incorporating data gathered through May.

The analysis included data from 206 patients who had sought medical attention after taking the supplements. Of them, follow-up data was available for 105 patients, 85.7 percent of whom still had an eGFR below 60, indicating low kidney function.

This suggests that “many people still have chronic kidney disease (linked to the supplement),” said Yoshitaka Isaka, vice president of the society and professor of nephrology at Osaka University, who led the study.

Most of the patients are middle-aged or older, with 38 percent in their 50s, 32 percent in their 60s, and 16 percent in their 40s. More than half, or 67 percent, were women.

Many patients had symptoms and test results suggesting Fanconi syndrome, a condition caused by damage to the renal tubules in the kidneys. Nearly 20 percent were receiving treatment with steroid drugs.

Of the 110 patients who underwent kidney biopsies, 47 percent had tubulointerstitial nephritis, an inflammation of the kidneys, and 28 percent had tubular necrosis, a form of kidney cell death.

The symposium also discussed the case of a woman in her 90s who died after taking the benikoji supplements. She was among the five initial deaths reported by Kobayashi Pharmaceutical.

The woman had started taking the company’s Benikoji Coleste Help supplement before March 2023. In December that year, she was hospitalized with a fever, fatigue, loss of appetite, and was diagnosed with Fanconi syndrome.

While her kidney function improved during hospitalization, the woman’s overall health deteriorated due to sarcopenia, a condition characterized by muscle loss common in older adults.

She died in February 2024. Her doctor commented that while kidney function decline was not the direct cause of her death, it was a contributing factor.

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