A 23-year-old woman from Kochi Prefecture has developed a serious liver ailment since May, when she began drinking tea that the manufacturer claims helps people lose weight, the health ministry said.

Four people have died and more than 800 people across Japan have been taken ill after consuming two types of Chinese-made diet aid products that contain banned chemicals. Health ministry officials said Friday that the case in Kochi is the first linked to diet tea.

According to a medical report filed with the Ministry of Health, Labor and Welfare, the Kochi woman, who was not named, received a blood plasma transfusion at a Kochi city hospital after her hepatic functions deteriorated dramatically.

Although the patient’s condition was later relatively stable, the hospital is considering a liver transplant.

The Kochi woman, who lives in Muroto, in May started taking a diet tea sold under the Huahong Liulu Tea label and became sick in late September. The Chinese label means “red flower and green willow tea.”

The woman was treated at a hospital in Muroto before she was transferred to the Koichi city hospital.

The Huahong Liulu Tea, which claims drinkers will lose weight and have other health benefits, is not on the health ministry’s list of Chinese diet products that are hazardous to health.

Health officials say there is no evidence yet to link the tea with the Kochi woman’s medical condition. The ministry is conducting an analysis of the active ingredients of the tea.

According to the firm that produces Huahong Liulu Tea and other sources, the tea was blended from Japanese and imported tea leaves at a facility in Miyagi Prefecture and distributed by a company in Kawaguchi, Saitama Prefecture.

The company’s Web site claims the tea is produced under strict quality control guidelines and the imported ingredients have been cleared in safety inspections by customs authorities.