1. Introduction
Background: Cognitive functions decline with age. Declined cognitive functions negatively affect daily behaviors. Previous studies showed the positive effect of spices and herbs on cognition. In this study, we investigated the positive impact of wasabi, which is a traditional Japanese spice, on cognitive functions. The main bioactive compound of wasabi is 6-MSITC (6 methylsulfinyl hexyl isothiocyanate), which has anti-oxidant and anti-inflammatory functions. Anti-oxidants and anti-inflammatories have an important role in cognitive health. Therefore, 6-MSITC is expected to have positive effects on cognitive function. Previous studies showed the beneficial effects on cognitive functions in middle-aged adults. However, it is unclear that 6-MSITC has a positive effect on cognitive functions in healthy older adults aged 60 years and over. Here, we investigated whether 12 weeks’ 6-MSITC intervention enhances cognitive performance in older adults using a double-blinded randomized controlled trial (RCT). Methods: Seventy-two older adults were randomly assigned to 6-MSITC or placebo groups. Participants were asked to take a supplement (6-MSITC or a placebo) for 12 weeks. We checked a wide range of cognitive performances (e.g., executive function, episodic memory, processing speed, working memory, and attention) at the pre- and post-intervention periods. Results: The 6-MSITC group showed a significant improvement in working and episodic memory performances compared to the placebo group. However, we did not find any significant improvements in other cognitive domains. Discussion: This study firstly demonstrates scientific evidence that 6-MSITC may enhance working memory and episodic memory in older adults. We discuss the potential mechanism for improving cognitive functions after 6-MSITC intake.Cognitive performances decline with age [Nutrition is an important factor for cognitive health in older adults [Recent studies have also demonstrated that spices and herbs have health benefits [Wasabi (Eutrema japonicum) is a Japanese traditional spice. In Japan, wasabi is popular. The main bioactive compound of wasabi is Hexaraphane (6 methylsulfinyl hexyl isothiocyanate: 6-MSITC), which is an isothiocyanate family [Only two studies investigated beneficial effects of 6-MSITC on cognitive functions [In this study, we tested whether 12 weeks’ 6-MSITC intake would enhance cognitive performances in older adults. In this study, we made three main hypotheses. First, we hypothesized that 6-MSITC would improve episodic memory as well as working memory performances in older adults because a previous study on patients using 6-MSITC reported a significant improvement of the subjective severity of brain fog symptoms [