This randomized, double-blind, placebo-controlled trial will evaluate whether 12 weeks of supplementation with the probiotic Lactobacillus rhamnosus GG combined with colon-delivered riboflavin will improve cognitive performance and brain physiology in older adults with memory complaints. The study will assess changes in cognitive outcomes together with neurophysiological markers to explore potential gut-brain axis mechanisms. Through its rigorous design, the trial will aim to determine whether targeted modulation of the intestinal environment can support brain function and cognitive health in aging.