A randomized, placebo‐controlled trial evaluating the safety of excessive administration of kaempferol aglycone

Kaempferol (KMP) is an important flavonoid in many fruits and vegetables. Preclinical studies on KMP have reported its pharmacological effects, including antimicrobial, antioxidant, anti‐inflammatory, antitumor, antidiabetic, myocardial protective, and neuroprotective effects. Additionally, some epidemiological studies have revealed a negative association between the consumption of KMP‐containing foods and the risk of developing several disorders, such as cancer and cardiovascular diseases. Thus, although a large body of literature has demonstrated the benefits of KMP supplementation, there are no reports of clinical trials evaluating the safety of KMP aglycone administration or KMP aglycone‐rich food consumption. The purpose of this study was to evaluate the safety of a high dose of KMP aglycone by administrating KMP aglycone‐containing supplements to healthy adults. This study had a randomized, double‐blind, placebo‐controlled design and a 4‐week duration. Participants were randomly allocated to the KMP (n = 24) or placebo (n = 24) group. For 4 weeks, the KMP group received a capsule containing 50‐mg KMP daily, a dose approximately five times higher than the estimated human dietary intake. The placebo group received a capsule containing cornstarch‐based powder daily. The general toxicity parameters were evaluated by examining the characteristics of the participants, hematological and blood biochemical parameters, general urinalysis, qualitative urine tests, and adverse events. No clinical changes were observed in anthropometric and blood pressure measurements or blood and urine parameters in the KMP group compared to those in the placebo group. Furthermore, no adverse events owing to KMP aglycone administration occurred. The study results revealed that the consumption of 50‐mg KMP aglycone daily for 4 weeks is safe in healthy adults.