Aged garlic extract is produced by soaking slices of garlic in ethanol for up to 20 months. The extract is then filtered and concentrated. It contains many active ingredients found in garlic such as S-allyl-L-cysteine, di-allyl-disulfide, flavonoids, and other compounds that could improve blood vessels and reduce oxidative stress. No studies have directly tested whether aged garlic extract improves cognitive functions in humans; however, aged garlic extract may reduce high blood pressure, a risk factor for Alzheimer’s disease. Aged garlic extract is generally safe, with potential gastrointestinal side effects; however, it may interact with blood thinners and its long-term safety is unknown.
No clinical trials have tested whether aged garlic extract improves cognitive function or prevents age-related cognitive decline. Aged garlic extract may reduce blood pressure, a risk factor for Alzheimer’s disease. Our search identified:
No studies have reported that aged garlic extract can improve cognitive functions or prevent age-related cognitive decline. However, it may reduce high blood pressure, a risk factor for Alzheimer’s disease [1]. Randomized clinical trials have reported that aged garlic extract over a 12-week treatment period can reduce systolic blood pressure by 5-15 mmHg in adults with hypertension, even in individuals already taking anti-hypertensive medications [2; 3; 4; 5].
In preclinical studies, aged garlic extract treatment reduced oxidative stress, inflammation, and neuronal loss, while improving neuronal connections and cognitive functions [6; 7; 8; 9; 10]. However, no studies in humans have confirmed these findings.
No published studies have reported whether aged garlic extract is beneficial in Alzheimer’s patients or people with other dementias.
Some evidence from preclinical studies suggest that aged garlic extract may reduce biological markers of Alzheimer’s (i.e., amyloid and tau), oxidative stress, inflammation, and neuronal loss, while improving cognitive functions [6; 7; 8; 11; 12; 13]. However, these results have not been confirmed in humans.
Clinical trials suggest that aged garlic extract is safe, with the most common side effect being gastrointestinal in nature [2; 3; 4]. However, it contains many active ingredients found in garlic, which may interact with other blood thinning drugs (e.g., warfarin or aspirin) and is not recommended before surgery [14]. There is insufficient evidence whether aged garlic extract might also increase the risk of bleeding, though one short randomized clinical trial suggested it did not [3]. However, most of the aged garlic extract trials were short with few patients. Longer clinical trials with more patients are needed to establish long-term safety.
NOTE: This is not a comprehensive safety evaluation or complete list of potentially harmful drug interactions. It is important to discuss safety issues with your physician before taking any new supplement or medication.
Aged garlic extract is available over the counter as a supplement in pill form. The doses tested in clinical trials ranged from 960 – 2400 mg/day. However, the recommended dose will depend on the specific method of preparation, which may vary from one supplement brand to another. It is recommended that aged garlic extract be taken with a meal.
For more information on the use and safety of garlic (not specifically aged garlic extract), see the National Institute of Health’s National Center for Complementary and Integrative Health page
Full scientific report (PDF) on Cognitive Vitality Reports