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Aged Garlic Extract

  • Vitamins & Supplements
  • Updated April 7, 2021

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.

Evidence

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:

  • 4 randomized clinical trials of aged garlic extract for blood pressure reduction
  • 8 preclinical studies

Potential Benefit

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.

For Dementia Patients

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.

Safety

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.

How to Use

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.

Learn More

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

References

  1. Lennon MJ, Makkar SR, Crawford JD et al. (2019) Midlife Hypertension and Alzheimer's Disease: A Systematic Review and Meta-Analysis. J Alzheimers Dis  71, 307-316.
  2. Ried K, Frank OR, Stocks NP (2010) Aged garlic extract lowers blood pressure in patients with treated but uncontrolled hypertension: a randomised controlled trial. Maturitas  67, 144-150.
  3. Ried K, Travica N, Sali A (2016) The effect of aged garlic extract on blood pressure and other cardiovascular risk factors in uncontrolled hypertensives: the AGE at Heart trial. Integr Blood Press Control  9, 9-21.
  4. Ried K, Frank OR, Stocks NP (2013) Aged garlic extract reduces blood pressure in hypertensives: a dose-response trial. Eur J Clin Nutr  67, 64-70.
  5. Ried K, Travica N, Sali A (2018) The Effect of Kyolic Aged Garlic Extract on Gut Microbiota, Inflammation, and Cardiovascular Markers in Hypertensives: The GarGIC Trial. Front Nutr  5, 122.
  6. Li F, Kim MR (2019) Effect of Aged Garlic Ethyl Acetate Extract on Oxidative Stress and Cholinergic Function of Scopolamine-Induced Cognitive Impairment in Mice. Prev Nutr Food Sci  24, 165-170.
  7. Chauhan NB (2006) Effect of aged garlic extract on APP processing and tau phosphorylation in Alzheimer's transgenic model Tg2576. J Ethnopharmacol  108, 385-394.
  8. Thorajak P, Pannangrong W, Welbat JU et al. (2017) Effects of Aged Garlic Extract on Cholinergic, Glutamatergic and GABAergic Systems with Regard to Cognitive Impairment in Abeta-Induced Rats. Nutrients  9.
  9. Nillert N, Pannangrong W, Welbat JU et al. (2017) Neuroprotective Effects of Aged Garlic Extract on Cognitive Dysfunction and Neuroinflammation Induced by beta-Amyloid in Rats. Nutrients  9.
  10. Ray B, Chauhan NB, Lahiri DK (2011) Oxidative insults to neurons and synapse are prevented by aged garlic extract and S-allyl-L-cysteine treatment in the neuronal culture and APP-Tg mouse model. J Neurochem  117, 388-402.
  11. Chauhan NB (2003) Anti-amyloidogenic effect of Allium sativum in Alzheimer's transgenic model Tg2576. J Herb Pharmacother  3, 95-107.
  12. Chauhan NB, Sandoval J (2007) Amelioration of early cognitive deficits by aged garlic extract in Alzheimer's transgenic mice. Phytother Res  21, 629-640.
  13. Jeong JH, Jeong HR, Jo YN et al. (2013) Ameliorating effects of aged garlic extracts against Abeta-induced neurotoxicity and cognitive impairment. BMC Complement Altern Med  13, 268.
  14. Wong WW, Gabriel A, Maxwell GP et al. (2012) Bleeding risks of herbal, homeopathic, and dietary supplements: a hidden nightmare for plastic surgeons? Aesthet Surg J  32, 332-346.