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.

Inclusion Criteria:

• Age > 65 years
• MoCA scores 18-25 points
• BMI of 20.0 - 29.9 kg/m2 at screening
• Stable body weight (≤ 5% change) over the past 3-months
• Willing to avoid consuming gut microbiome-modulating dietary supplements within 4 weeks prior to the baseline visit
• Subjects will abstain from vitamin B2-rich food intake as per pre-defined list
• Maintain current level of physical activity
• Be willing and able to comply with trial protocol

Exclusion Criteria:

• Severe chronic disease and acute injuries
• History of dietary supplement use four weeks before enrolment
• Organic gastrointestinal (GI) disorders
• Bowel surgery or short bowel syndrome
• Gut-altering medications two months before enrolment
• Is currently using systemic steroids, proton pump inhibitors, H2 blocker, antacid
• History of drug and/or alcohol abuse at the time of enrolment
• Smoker or vaper
• Has made any major dietary changes in the past 3 months prior to baseline
• Has a currently active eating disorder
• Has food allergies or other issues with foods

Data obtained through this study may be provided to qualified researchers with academic interest in nutritional science. Data will be coded, with no PHI included. Approval of the request and execution of all applicable agreements are prerequisites to the sharing of data with the requesting party.

Data requests can be submitted starting 9 months after article publication and the data will be made accessible for up to 24 months. Extensions will be considered on a case-by-case basis.

Only qualified researchers with academic interest in nutritional science.