The consumption of onion extract tablet modulates expression of human plasma microRNAs: a randomized placebo-controlled clinical trial

MicroRNAs (miRNAs), which are non-coding RNAs of approximately 20 nucleotides in length, have attracted attention for their involvement in various biological processes and the regulation of diseases. However, the effects of foods and supplements on miRNA expression in vivo remain unclear. Onion extract tablets (OET) alleviate male menopausal symptoms and stress; however, their effects on miRNA expression in vivo are unknown. Herein, we investigated the effects of OET on miRNA expression in vivo. A randomized, double-blind, placebo-controlled study was conducted on 19 healthy Japanese participants (men and women) aged 30-65 years. Participants consumed either a placebo tablet (PT) or OET which included 30 mg of sulfur-containing amino acids daily for 2 weeks. MiRNAs prepared from plasma samples before and after intake were comprehensively analyzed using next-generation sequencing. A comparison of the variation before and after intake showed that the expression levels of three miRNAs, miR-106b-5p, miR-339-3p, and miR-181b-5p, were significantly increased in the OET group than in the PT group. Receiver operating characteristic analysis of these miRNAs also showed that miR-106b-5p had the highest discriminatory power. To our knowledge, this study is the first to show that consumption of onion extract can modulate miRNA expression in humans.