Context: Recently, new intervention tools at the mild cognitive impairment (MCI) stage are needed to prevent dementia, including Alzheimer's disease (AD). Aims: To evaluate whether a standardized Asparagus officinalis stem (ETAS) extract, as a functional ingredient, effectively maintains cognitive functions in subjects with normal aging and MCI. Methods: A pilot randomized controlled trial was conducted on thirty subjects that were randomly allocated to the experimental group (n = 15), which received ETAS supplementation (1,000 mg) daily, and a control group, which received placebo (dextrin) in the same form (n = 15) for a period of 12 months. All subjects were evaluated using neuropsychological questionnaires comprised of Mini-Mental State Examination (MMSE), Frontal Assessment Battery (FAB), Clock Drawing Test (CDT), and Hospital Anxiety and Depression Scale (HADS) at all visit times. Brain tests (MRI, EEG and EPB) and blood tests (hematology, hemochemistry, immunological status and HSP70) were also performed. Primary endpoints were the change in the neuropsychological questionnaire scores. Secondary endpoints such as immunological and molecular biomarkers of dementia, neurological imaging, and electrophysiological outcomes were measured. Results: The ETAS group showed a significant improvement in scores on MMSE, FAB, and HADS, tended to improve in scores on CDT, and could show a slight increase in blood HSP70. The ETAS group also maintained normal levels of CD4/CD8 immune complex. No adverse events were detected during the study period. Conclusions: ETAS supplementation could prevent the progression of cognitive decline and anxiety/depression expression associated with the prevention of AD.