Four-week supplementation with a blackcurrant formulation enhances cognitive performance, reduces mental fatigue and modulates peripheral monoamine metabolism in older adults: a randomized, double-blind, placebo-controlled, crossover study

Introduction Age-related cognitive decline is an increasing concern in older adults. While blackcurrants ( Ribes nigrum ) have shown promise in improving cognitive outcomes in younger adults, their efficacy in supporting cognitive function in older adults is largely unexplored. Methods In this randomized, placebo-controlled, double-blinded crossover study of healthy older adults (62 ± 1 years), 26 of the 30 participants enrolled completed the study per protocol. Participants consumed either a placebo or a flavonoid-rich blackcurrant formula (BCF, 7.8 mg anthocyanins/kg body weight freeze-dried blackcurrant, 200 mg L-theanine, and 100 mg pine bark extract) in a beverage format daily for 4 weeks, with interventions separated by a two-week washout period. For each intervention, cognitive and mood outcomes were assessed following a single dose (acute) and after 4 weeks’ supplementation. Platelet MAO-B activity, circulating neurotransmitter concentrations, and anthocyanin, L-theanine and sarmentosin bioavailability were measured from venous blood samples drawn at baseline, 1 h, 2.4 h and 4 wk after intervention supplementation. Results A significant reduction in Rapid Visual Information Processing (RVIP) false alarms ( p = 0.022) and a strong trend in reduced mental fatigue ( p = 0.046, q = 0.067) were measured following 4 weeks of BCF supplementation. Reduction in biomarkers of MAO activity were measured following acute supplementation with BCF, but not placebo, with significant treatment × time interactions ( q < 0.01) for platelet MAO-B activity, plasma 5-hydroxyindoleacetic acid and 3,5-dihydroxyphenylglycine concentrations. These changes corresponded with significant reductions ( q < 0.05) in circulating neurotransmitter metabolites xanthurenic acid, 3-methoxy-4-hydroxyphenylglycol and vanillylmandelic acid. Conclusion Findings from this study indicate that 4 weeks of BCF supplementation sustained attention in healthy older adults, extending evidence for BCF-related cognitive benefits across both younger and older populations. Clinical Trial Registration https://anzctr.org.au/ , identifier: ACTRN12621001590853.