The purpose of this study was to evaluate the effects of daily glycine supplementation on metabolic health and cognitive performance in older adults. Over a period of six months, participants received 1,000 mg of glycine per day to determine if this amino acid could improve markers of insulin resistance, glucose metabolism, and cognitive functions such as memory and executive tasks.

The research aimed to identify whether this nutritional intervention provides a safe and effective strategy to support healthy aging, focusing on the link between metabolic balance and brain health in the elderly population.

A 6-month longitudinal study was conducted, featuring a glycine supplementation phase followed by a dietary maintenance period. Cognitive assessments and serum BDNF levels were monitored at baseline, 3 months (T3), and 6 months (T6). Which included the evaluation of fasting glucose, insulin levels, insulin resistance indices, and specific metabolic biomarkers. Concurrently, cognitive functions were evaluated utilizing standardized neuropsychological instruments to measure changes in memory, attention, and executive function. Linear Mixed-Effects Models (LMM) were used to analyze temporal trajectories.

Inclusion Criteria:

-Individuals across all nutritional statuses according to Body Mass Index (BMI): underweight, normal weight, overweight, and obesity.

Exclusion Criteria:

• Clinically relevant comorbidities (requiring patient hospitalization or a diagnosis of any infectious/contagious disease).
• Consumption of polyphenol-based supplements or herbal blends within the two weeks prior to the study.
• Mental incapacity.
• Lack of willingness.
• Language barriers that prevent adequate understanding or co-operation.

Individual participant data will not be shared to protect the privacy and confidentiality of the participants, in accordance with the informed consent and the guidelines of the Institutional Review Board (IRB).