Rice wine lees (RWL), a Japanese traditional fermented product, is a rich source of one-carbon metabolism-related nutrients, which may have beneficial effects on cognitive function.

We aimed to examine the effect of the RWL on cognitive function in community-dwelling physically active older adults.

Double-blind, randomized, placebo-controlled study (clinical trial number: UMIN 000027158).

Community-based intervention including assessments conducted at the University of Hyogo and a public liberal arts school in Himeji City, Japan.

A total of 35 community-dwelling older adults (68–80 years) who performed mild exercise before and during the trial were assigned to either the RWL (n=17) or the placebo group (n=18).

Daily consumption of 50 g RWL powder, which contained one-carbon metabolism-related nutrients, or the placebo powder (made from soy protein and dextrin) for 12 weeks. Both supplements included equivalent amounts of energy and protein.

Montreal Cognitive Assessment, computerized cognitive function test, and measurements of serum predictive biomarkers (transthyretin, apolipoprotein A1, and complement C3) were conducted at baseline and follow-up.

Visual selective attention and serum transthyretin significantly improved in the RWL group, whereas there was no significant change in the placebo group. No significant group difference was observed in the remaining cognitive performance tests.

RWL supplements seem to have a few effects on cognitive function in community-dwelling physically active older adults. However, the impact was limited; therefore, further studies with sufficient sample size are warranted to elucidate this issue.