Formaldehyde produced from d-ribose under neutral and alkaline conditions

•d-ribose can produce formaldehyde under neutral and alkaline conditions in vitro.•Administration of d-ribose induces an increase of formaldehyde in the brain of mice.•Formaldehyde in urine and serum should be monitored for a person especially an elderly individual to take d-ribose. Formaldehyde is toxic and has been implicated in the pathologies of various diseases, such as cognitive impairment and cancer. Though d-ribose is widely studied and provided as a supplement to food such as flavor and drinks, no laboratories have reported that d-ribose is involved in the formaldehyde production. Here, we show that formaldehyde is produced from d-ribose in lysine or glycine solution and Tris−HCl buffer under neutral and alkaline conditions. Intraperitoneal injection of C57BL/6J mice with d-ribose significantly increased the concentration of brain formaldehyde, compared to the injection with d-glucose or saline. These data suggest that formaldehyde levels should be monitored for the people who take d-ribose as a supplement.