Wise Mind Herbs

The information on this page has been prepared with reference to published scientific literature, not by a medically qualified expert. It is not medical advice. Any decision to use a supplement or herb-based product is your responsibility. Consult a suitably qualified medical professional, especially if you have underlying conditions. Remember, nothing is for everyone, and not everything sold is what it claims to be. Some things work for some people, some of the time.

Garlic - Allium sativum

Garlic (Allium sativum L.) is a bulbous plant belonging to the Amaryllidaceae family. It has been used for thousands of years both as a culinary ingredient and medicinal plant across numerous cultures worldwide. Modern scientific research has validated many of its traditional uses, revealing a complex biochemical profile responsible for its therapeutic properties.

Botanical Classification and Common Names

Botanical name: Allium sativum L. (cultivated garlic)

Common names: Garlic, common garlic, cultivated garlic, poor man's treacle, rustic treacle, nectar of the gods, stinking rose, and camphor of the poor.

Plants sometimes confused with garlic but are distinct species include:

• Allium ursinum (wild garlic, bear's garlic, or ramsons)
• Allium vineale (crow garlic or wild garlic)
• Allium tuberosum (Chinese chives or garlic chives)
• Tulbaghia violacea (society garlic)
• Allium canadense (meadow garlic or wild onion)

Bioactive Compounds

Garlic's medicinal properties primarily stem from organosulfur compounds including:

• Allicin (produced when fresh garlic is crushed or chopped, converting alliin to allicin via the enzyme alliinase)
• Alliin (S-allyl-L-cysteine sulfoxide)
• Diallyl disulfide (DADS)
• Diallyl trisulfide (DATS)
• S-allyl cysteine (SAC)
• S-allylmercaptocysteine (SAMC)

Additional bioactive components include flavonoids, saponins, phenolic compounds, and various vitamins and minerals.

Evidence-Based Health Benefits

Research has demonstrated several therapeutic properties of garlic, with varying levels of evidence:

Strong Evidence:

• Cardiovascular benefits: Modest reductions in blood pressure (5-8 mmHg systolic, 2-5 mmHg diastolic), total cholesterol (reduction of 4-12%), and LDL cholesterol (reduction of 6-13%)
• Antimicrobial activity: Effective against various bacteria (including some drug-resistant strains), fungi, viruses, and parasites
• Antioxidant effects: Protection against oxidative damage through free radical scavenging and enhancement of endogenous antioxidant systems

Moderate Evidence:

• Immunomodulatory effects: Enhancement of immune function and reduction of inflammation
• Cancer prevention: Potential protective effects against colorectal, gastric, and prostate cancers
• Diabetic management: Modest improvements in blood glucose control and insulin sensitivity

Preliminary Evidence:

• Neuroprotective effects: Potential benefits for cognitive function and protection against neurodegenerative diseases
• Respiratory condition management: Reduction in frequency and severity of common colds
• Liver protection: Potential hepatoprotective effects against toxins
• Bone health: Possible prevention of bone loss in menopausal women

Recommended Dosages

Dosage recommendations vary based on preparation and intended therapeutic effect:

• Fresh garlic: 1-2 cloves (4-8g) daily
• Aged garlic extract: 600-1,200mg daily (standardized to contain 0.25-1.0% S-allyl cysteine)
• Garlic powder: 300-1,200mg daily (standardized to 0.6-1.3% alliin or approximately 0.6% allicin potential)
• Garlic oil: 5-20mg daily (containing allyl sulfides but minimal allicin)

For specific conditions, research suggests:

• Hypertension: 600-1,200mg of aged garlic extract daily
• Hyperlipidemia: 900mg of garlic powder daily (standardized to 1.3% alliin)
• Infection prevention: 2-5g of fresh garlic daily

Maximum Efficacious Range and Higher Doses

Most clinical studies have used doses within the ranges mentioned above, with diminishing returns observed at higher doses. Limited research exists on substantially higher doses, creating a knowledge gap. Some studies suggest doses exceeding 3,000mg daily do not provide additional benefits for cardiovascular parameters but may increase the risk of side effects. No well-designed clinical trials have systematically investigated extremely high doses (>5g equivalent of fresh garlic daily) for extended periods, representing a significant research gap. Preliminary animal studies indicate potential hepatotoxicity at very high doses, but human data remains sparse.

Side Effects and Adverse Reactions

Garlic is generally recognized as safe (GRAS) when consumed in food amounts, but medicinal doses may cause:

• Gastrointestinal effects: Heartburn, flatulence, nausea, vomiting, diarrhea, and gastric irritation
• Breath and body odor: Due to sulfur-containing metabolites
• Allergic reactions: Ranging from contact dermatitis to rare anaphylaxis
• Bleeding risk: Platelet aggregation inhibition and increased fibrinolytic activity
• Drug interactions: Potential interactions with anticoagulants, antiplatelet medications, antidiabetics, and certain HIV medications

Less common side effects include headaches, fatigue, decreased serum protein and calcium levels, and increased risk of postoperative bleeding.

Contraindications

Therapeutic doses of garlic should be avoided or used with caution in:

• Individuals scheduled for surgery (discontinue at least 7-10 days before)
• Patients on anticoagulant/antiplatelet therapy
• Those with bleeding disorders
• Pregnant and breastfeeding women (medicinal doses)
• Individuals with gastrointestinal disorders or irritable bowel syndrome

Commercial Pharmaceutical Products

While numerous garlic supplements exist, few meet the criteria of regulated pharmaceutical products. Those that do include:

• Kwai® Heart Care: Standardized garlic tablets used in multiple clinical trials for cardiovascular health
• Kyolic® Aged Garlic Extract: Pharmaceutical-grade aged garlic extract with numerous clinical studies supporting its efficacy
• Allicor®: Standardized garlic powder tablet developed for cardiovascular disease prevention
• CardioAce® Original: Combined garlic extract with other cardiovascular support compounds
• Allimax® Pro: Professional-strength allicin supplement used in some clinical settings

Synthetic analogues of garlic compounds in development or limited use include:

• S-allylcysteine analogues for neuroprotection (research phase)
• Ajoene derivatives for antiplatelet therapy (research phase)
• DATS-based compounds for anticancer applications (preclinical)

Current Research Gaps

Despite extensive research, significant knowledge gaps remain:

• Standardization issues: Variable preparation methods and active compound concentrations complicate comparison between studies
• Long-term effects: Limited data on safety and efficacy beyond 12 months of use
• Optimal formulations: Unclear which garlic preparation is most effective for specific conditions
• Personalized dosing: Limited understanding of genetic factors affecting response to garlic compounds
• Interaction mechanisms: Incomplete understanding of complex interactions with medications and other supplements

References

Ackermann, R. T., Mulrow, C. D., Ramirez, G., Gardner, C. D., Morbidoni, L., & Lawrence, V. A. (2001). Garlic shows promise for improving some cardiovascular risk factors. Archives of Internal Medicine, 161(6), 813-824.

Bayan, L., Koulivand, P.H. and Gorji, A., 2014. Garlic: a review of potential therapeutic effects. Avicenna journal of phytomedicine, 4(1), p.1.

Bradley, J. M., Organ, C. L., & Lefer, D. J. (2016). Garlic-derived organic polysulfides and myocardial protection. The Journal of nutrition, 146(2), 403S-409S.

Donma, M. M., & Donma, O. (2020). The effects of allium sativum on immunity within the scope of COVID-19 infection. Medical hypotheses, 144, 109934.

Du, Y., Zhou, H., & Zha, W. (2024). Garlic consumption can reduce the risk of dyslipidemia: a meta-analysis of randomized controlled trials. Journal of Health, Population and Nutrition, 43(1), 113.

Kimura, S., Tung, Y. C., Pan, M. H., Su, N. W., Lai, Y. J., & Cheng, K. C. (2016). Black garlic: A critical review of its production, bioactivity, and application. Journal of food and drug analysis, 25(1), 62.

Okoro, B. C., Dokunmu, T. M., Okafor, E., Sokoya, I. A., Israel, E. N., Olusegun, D. O., ... & Iweala, E. E. J. (2023). The ethnobotanical, bioactive compounds, pharmacological activities and toxicological evaluation of garlic (Allium sativum): A review. Pharmacological Research-Modern Chinese Medicine, 8, 100273.

Saadh, M. J., Shukla, M., Ballal, S., Kumar, A., Chahar, M., Saini, S., ... & Hasaanzadeh, S. (2024). Effects of Aged Garlic Extract on blood pressure in hypertensive patients: A systematic review and meta-analysis of randomized controlled trials. Prostaglandins & Other Lipid Mediators, 106914.

Zhao, X., Cheng, T., Xia, H., Yang, Y., & Wang, S. (2024). Effects of Garlic on Glucose Parameters and Lipid Profile: A Systematic Review and Meta-Analysis on Randomized Controlled Trials. Nutrients, 16(11), 1692.