Garlic — Allium sativum

Common & Latin Names

Common names: Garlic, Common garlic, Cultivated garlic, Poor man’s treacle, Stinking rose Latin name: Allium sativum L. TCM name: Da Suan (大蒜) Sanskrit/Ayurvedic: Lasuna, Rasona (“lacking one” — it is said to possess five of the six tastes, lacking only sour) Arabic: Thawm German: Knoblauch

Plant Family & Parts Used

Family: Amaryllidaceae (amaryllis family; formerly classified in Alliaceae/Liliaceae — also includes onion, leek, shallot, chive) Parts used: Bulb (the cloves) — both fresh and in various processed forms. The processing method dramatically affects the phytochemical profile:

Fresh garlic: Highest in allicin (formed when cloves are crushed/chopped)
Aged garlic extract (AGE): Allicin is converted to S-allylcysteine (SAC) and other water-soluble organosulfur compounds. Odorless and better tolerated.
Garlic oil: Rich in diallyl sulfide (DAS), diallyl disulfide (DADS), and diallyl trisulfide (DATS). Fat-soluble organosulfur compounds.
Dehydrated garlic powder: Retains alliin, which converts to allicin when the powder is rehydrated.

Habitat: Believed to originate from Central Asia (possibly Kazakhstan/Kyrgyzstan). Cultivated worldwide for over 5,000 years. One of the oldest cultivated plants — it was given to the builders of the Egyptian pyramids (recorded in inscriptions at Giza). Cultivated in every temperate and subtropical region on Earth. China produces over 80% of the world’s garlic.

Traditional Uses

Ancient Egyptian Medicine (3,500+ years)

The Ebers Papyrus (circa 1550 BCE) lists 22 garlic-based remedies for a range of conditions including infections, tumors, heart conditions, and parasites. Garlic was fed to pyramid-building laborers for endurance and to prevent disease. Egyptian priests reportedly avoided garlic because of its stimulating properties, while the working classes consumed it enthusiastically.

Ayurvedic Medicine (3,000+ years)

Lasuna is one of the most valued medicinal foods in Ayurveda, though it has a complex place in the tradition. The Charaka Samhita describes it as Rasayana (rejuvenative) and lists it among the finest cardiac tonics. However, it is classified as Tamasic (dulling to the mind) in the Sattvic dietary system — yogis and brahmins traditionally avoided garlic because it was believed to increase Rajas (passion) and Tamas (inertia), interfering with meditation. Despite this spiritual caution, Ayurveda extensively uses garlic for:

Hridya (cardiac tonic): Reduces cholesterol, strengthens the heart
Krimighna (anti-parasitic): Intestinal parasites, infections
Vatahara (Vata-reducing): Joint pain, neurological conditions, cold conditions
Respiratory conditions: Asthma, bronchitis, chronic cough
Rasona Vati and Lasunadi Ghrita are classical preparations

TCM

Da Suan is classified as a warm, pungent herb that enters the Spleen, Stomach, and Lung meridians:

Resolves toxicity (antibacterial, antifungal, antiparasitic)
Kills parasites (intestinal worms, dysentery)
Reduces food stagnation
Warms the Middle Jiao
Treats Cold-type diarrhea and dysentery

In TCM, garlic is more commonly used as a food medicine and external application (moxibustion over garlic slices) rather than in decocted herbal formulas, because its volatile compounds are destroyed by prolonged boiling.

Western Herbalism and Folk Medicine

In every European folk tradition, garlic is the universal antimicrobial and cardiovascular protector. Hippocrates prescribed garlic for a variety of conditions. During the plague pandemics of medieval Europe, garlic was consumed and worn to prevent infection — “four thieves vinegar” (a garlic-based preparation) was allegedly used by grave robbers to avoid contracting plague from corpses. In World War I and II, garlic was used as an antiseptic for wound treatment when standard antibiotics were unavailable.

Global Indigenous Uses

Garlic or garlic-related Allium species are used medicinally in virtually every traditional medicine system on Earth. This universal recognition across unrelated cultures speaks to its undeniable clinical effects.

Active Compounds & Pharmacology

Primary Phytochemicals

Organosulfur compounds (the defining chemical class of garlic):

From fresh garlic (allicin pathway):

Alliin (S-allyl-L-cysteine sulfoxide): The primary precursor stored in intact garlic cells (0.5-1% of fresh weight). Stable and odorless.
Allicin (diallyl thiosulfinate): Formed instantly when alliin contacts the enzyme alliinase (released by crushing, cutting, or chewing garlic). Allicin is the pungent, characteristic garlic compound. Highly reactive, antimicrobial, and responsible for many of garlic’s acute biological effects. Unstable — breaks down within hours to:
- Ajoene: Anti-thrombotic, anti-cancer, anti-fungal
- Vinyldithiins: Anti-thrombotic
- Diallyl sulfides (DAS, DADS, DATS): The primary oil-soluble organosulfur compounds. Phase II detoxification enzyme inducers, anti-cancer, anti-inflammatory.

From aged garlic extract (water-soluble pathway):

S-allylcysteine (SAC): The primary water-soluble organosulfur compound. Potent antioxidant, cardioprotective, neuroprotective. More bioavailable and stable than allicin. This is the key compound in AGE (Kyolic brand) preparations.
S-allylmercaptocysteine (SAMC): Anti-cancer, hepatoprotective.
S-1-propenylcysteine: Immunomodulatory.

Other compounds: Fructo-oligosaccharides (prebiotic), flavonoids (quercetin, kaempferol), saponins, selenium (garlic is an excellent selenium accumulator), germanium, arginine.

Mechanisms of Action

Blood Pressure Reduction (Multiple Mechanisms): Garlic polysulfides are converted in red blood cells to hydrogen sulfide (H2S) — a gaseous signaling molecule (gasotransmitter) that relaxes vascular smooth muscle. Additionally, garlic inhibits angiotensin-converting enzyme (ACE), stimulates nitric oxide production, and activates potassium channels in vascular smooth muscle. The BP-lowering effect is consistent and clinically significant (Ried 2016).
Lipid Modification: Garlic inhibits HMG-CoA reductase (the same enzyme target as statin drugs), reduces cholesterol absorption in the gut, and enhances bile acid excretion. The LDL reduction is modest (8-15%) but consistent. More importantly, garlic inhibits LDL oxidation — the critical step converting LDL from benign to atherogenic.
Anti-atherogenic (Coronary Artery Calcification): Aged garlic extract reduces coronary artery calcium (CAC) scores — a direct measure of atherosclerotic plaque burden. The Varshney & Budoff studies demonstrate that AGE can slow or halt the progression of coronary calcification, a remarkable finding for a food-derived compound.
Antimicrobial (Broad-Spectrum): Allicin disrupts microbial cell membranes, inhibits bacterial enzymes by reacting with sulfhydryl groups, and interferes with RNA synthesis. Effective against Gram-positive and Gram-negative bacteria (including antibiotic-resistant strains like MRSA), fungi (Candida, Aspergillus), viruses (influenza, herpes simplex), and parasites (Giardia, Entamoeba).
Anti-platelet and Anti-thrombotic: Ajoene and diallyl disulfide inhibit platelet aggregation via thromboxane synthase inhibition and prostacyclin enhancement. This reduces blood clot formation without the bleeding risk of pharmaceutical anticoagulants at standard doses.
Cancer Prevention (Phase II Enzyme Induction): Diallyl sulfide and DADS induce Phase II detoxification enzymes (glutathione S-transferases, quinone reductases) that neutralize carcinogens. Garlic also induces apoptosis in cancer cells, inhibits angiogenesis, and modulates cell cycle progression. Epidemiological studies consistently show reduced cancer risk (particularly GI cancers) with regular garlic consumption.
Immune Enhancement: Garlic stimulates NK cell activity, macrophage phagocytosis, and T-cell proliferation. It enhances the response to vaccination (Nantz et al., 2012 showed aged garlic extract improved immune cell function and reduced cold/flu severity by 61%).

Clinical Evidence

Key Clinical Trials

Ried, K. (2016). “Garlic Lowers Blood Pressure in Hypertensive Individuals, Regulates Serum Cholesterol, and Stimulates Immunity: An Updated Meta-analysis and Review.” Journal of Nutrition, 146(2), 389S-396S.

Updated meta-analysis of 20+ RCTs on garlic and blood pressure
Garlic preparations (primarily AGE, 600-1200mg/day) reduced systolic blood pressure by an average of 8.6 mmHg and diastolic by 6.1 mmHg in hypertensive patients
This magnitude of BP reduction is clinically significant — comparable to first-line antihypertensive medications
Also reviewed evidence for cholesterol reduction (total cholesterol reduced by 8%) and immune stimulation
Concluded that “garlic supplementation with standardized preparations may provide a safe adjunctive treatment for hypertension and mildly elevated cholesterol”

Varshney, R., & Budoff, M.J. (2016). “Garlic and Heart Disease.” Journal of Nutrition, 146(2), 416S-421S.

Reviewed the evidence for aged garlic extract (AGE) in cardiovascular disease prevention
Highlighted landmark studies by Budoff and colleagues showing that AGE (2,400mg/day) significantly reduced coronary artery calcium (CAC) progression compared to placebo
AGE-treated patients showed a 7.5% increase in CAC over 12 months vs. 22.2% in placebo (p=0.01)
Reviewed mechanisms: H2S-mediated vasodilation, antioxidant protection, anti-inflammatory effects, lipid modification
Concluded: “Aged garlic extract has been shown to inhibit progression of coronary artery calcification, which is a strong predictor of future cardiovascular events”

Budoff, M.J., Takasu, J., Flores, F.R., et al. (2004). “Inhibiting progression of coronary calcification using Aged Garlic Extract in patients receiving statin therapy: a preliminary study.” Preventive Medicine, 39(5), 985-991.

19 patients on statin therapy, AGE (4mL/day) vs. placebo for 12 months
AGE group showed significantly slower CAC progression (p<0.05)
Demonstrated additive benefit to statin therapy — garlic provided cardiovascular protection beyond what statins achieve alone

Ried, K., Frank, O.R., Stocks, N.P., Fakler, P., & Sullivan, T. (2008). “Effect of garlic on blood pressure: a systematic review and meta-analysis.” BMC Cardiovascular Disorders, 8, 13.

11 RCTs meta-analyzed
Garlic reduced SBP by 4.6 mmHg overall, with greater reductions in hypertensive patients (8.4 mmHg SBP, 7.3 mmHg DBP)
Established the dose-response relationship: higher doses produced greater BP reductions

Nantz, M.P., Rowe, C.A., Muller, C.E., Creasy, R.A., Stanilka, J.M., & Percival, S.S. (2012). “Supplementation with aged garlic extract improves both NK and gammadelta-T cell function and reduces the severity of cold and flu symptoms: a randomized, double-blind, placebo-controlled nutrition intervention.” Clinical Nutrition, 31(3), 337-344.

120 healthy adults, AGE (2.56g/day) vs. placebo for 90 days during cold/flu season
AGE significantly enhanced NK and gamma-delta T cell proliferation
Reduced total number of cold/flu symptoms by 21% and reduced number of days ill by 61%
Confirmed garlic’s immune-enhancing effects in a well-designed RCT

Therapeutic Applications

Conditions

Hypertension: Clinically significant BP reduction (8-10 mmHg SBP in hypertensive patients)
Dyslipidemia: Moderate LDL and total cholesterol reduction (8-15%)
Atherosclerosis and CAC progression: Slows coronary artery calcification
Cardiovascular disease prevention (general): Multi-target cardioprotection
Infections (bacterial, viral, fungal, parasitic): Broad-spectrum antimicrobial
Immune support / Cold and flu prevention: Enhances NK cells, reduces illness severity
Cancer prevention: Strongest epidemiological evidence for gastric, colorectal, and esophageal cancers
Type 2 diabetes (adjunctive): Modest blood sugar reduction, cardiovascular risk reduction
SIBO and intestinal dysbiosis: Antimicrobial (particularly allicin-based preparations)
Candida overgrowth: Antifungal effects comparable to nystatin in some studies

Dosage Ranges

Aged garlic extract (Kyolic-type): 600-2400mg daily. Most studied for cardiovascular outcomes.
Fresh garlic: 2-5g daily (approximately 1-2 cloves). Must be crushed/chopped and allowed to sit for 10-15 minutes before cooking to allow allicin formation.
Garlic powder (alliin-containing): 600-1200mg daily (standardized to 1.3% alliin or 0.6% allicin yield)
Garlic oil capsules: 2-5mg daily (oil macerate or steam-distilled)
Allicin-stabilized supplements: 180-360mg daily (standardized to allicin content)
Tincture (1:5 in 45% alcohol): 2-4mL, 3 times daily

Forms and the Allicin Question

Different garlic preparations contain different active compounds with different therapeutic profiles:

AGE (aged garlic extract): Best for cardiovascular outcomes (BP, CAC, cholesterol). Odorless, well-tolerated. SAC is the primary active.
Allicin-rich preparations: Best for antimicrobial applications. More GI side effects.
Fresh crushed garlic: Broadest spectrum of compounds. Crush and wait 10 minutes before cooking to maximize allicin.
Cooked garlic: Loses most allicin but retains some organosulfur compounds and is gentler on the stomach.

Safety & Contraindications

Generally Well Tolerated

Garlic has been consumed as a food worldwide for 5,000+ years. At culinary doses, it is one of the safest substances on Earth. At supplemental doses, side effects are generally limited to GI effects and odor.

Contraindications

Pre-surgical: Discontinue garlic supplements (not culinary garlic) 7-14 days before surgery due to antiplatelet effects and potential for increased bleeding.
Active bleeding disorders: Antiplatelet properties may worsen bleeding.

Drug Interactions

Anticoagulants/antiplatelets (warfarin, heparin, aspirin, clopidogrel): Additive antiplatelet effect. Monitor INR with warfarin. Case reports of increased bleeding risk.
HIV protease inhibitors (saquinavir): Garlic significantly reduces saquinavir levels via CYP3A4 induction. Avoid combination.
Isoniazid: Garlic may reduce isoniazid absorption.
Cyclosporine: Potential for reduced cyclosporine levels.
Antihypertensives: Additive BP-lowering effect. Generally beneficial.
Antidiabetic medications: Additive blood sugar lowering. Monitor.

Pregnancy and Lactation

Culinary amounts are safe and have been consumed by pregnant and lactating women throughout human history. Supplemental doses are generally considered safe but may alter breast milk flavor (some infants reject garlic-flavored breast milk; others appear to enjoy it — one study showed increased breastfeeding duration when mothers consumed garlic).

Side Effects

Garlic breath and body odor (the most common “side effect”), GI discomfort (heartburn, nausea, bloating — more common with raw garlic and allicin-rich supplements), allergic reactions (rare — both contact and systemic), and mild increase in bleeding tendency at high supplemental doses. AGE preparations are significantly better tolerated than fresh garlic or allicin supplements.

Energetics

TCM Classification (Da Suan)

Temperature: Warm
Flavor: Acrid/pungent
Meridian entry: Spleen, Stomach, Lung
Actions: Resolves toxicity, kills parasites, reduces food stagnation, warms the Middle Jiao, dispels cold-dampness
TCM pattern correspondence: Cold-damp in the Middle Jiao (cold abdominal pain, diarrhea from cold), toxic accumulation (infections, parasites), food stagnation

Ayurvedic Classification

Rasa (taste): Katu (pungent), Tikta (bitter), Madhura (sweet), Lavana (salty), Kashaya (astringent) — all five tastes except sour, hence the name “Rasona” (lacking one)
Virya (energy/potency): Ushna (very heating)
Vipaka (post-digestive effect): Katu (pungent)
Dosha effects: Strongly pacifies Vata and Kapha. Significantly increases Pitta — garlic is one of the most heating foods in Ayurveda.
Guna (qualities): Tikshna (sharp/penetrating), Snigdha (unctuous/oily), Guru (heavy)
Dhatu affinity: Rasa (plasma), Rakta (blood), Mamsa (muscle), Meda (fat), Asthi (bone), Majja (marrow), Shukra (reproductive) — garlic is said to nourish ALL seven dhatus
Srotas affinity: Annavaha (digestive), Pranavaha (respiratory), Raktavaha (circulatory)
Classification: Tamasic (dulling/grounding) — despite its extraordinary medicinal properties, garlic is avoided in Sattvic diets for meditation because it is considered too stimulating and grounding

Functional Medicine Integration

Garlic is the most well-studied cardiovascular food-medicine and a cornerstone of evidence-based integrative cardiovascular care.

Cardiovascular Prevention Protocol

For patients with cardiovascular risk (hypertension, dyslipidemia, family history, elevated CAC scores), aged garlic extract (1200-2400mg/day) provides multi-target protection: BP reduction, LDL reduction and oxidation prevention, CAC progression inhibition, antiplatelet protection, and anti-inflammatory effects. Combined with hawthorn, omega-3 fatty acids, CoQ10, and magnesium, it forms the botanical-nutritional foundation of cardiovascular prevention.

Antimicrobial Protocol

For SIBO, Candida overgrowth, and intestinal dysbiosis, allicin-rich garlic preparations (particularly stabilized allicin supplements like Allimed/Allimax) provide broad-spectrum antimicrobial activity comparable to pharmaceutical antimicrobials. In the Johns Hopkins study (Chedid et al., 2014), herbal antimicrobials (which commonly include garlic-based preparations) were as effective as rifaximin for SIBO eradication.

Immune Support Protocol

For cold and flu prevention, AGE (2.56g/day) during cold/flu season reduces illness severity by 61% (Nantz 2012). This is more effective than vitamin C supplementation and comparable to oseltamivir (Tamiflu) for reducing symptom duration. In functional medicine immune protocols, garlic is combined with elderberry, vitamin D, zinc, and astragalus.

Cancer Prevention Protocol

The epidemiological evidence for garlic’s cancer-protective effects is among the strongest for any single food. The Iowa Women’s Health Study found that garlic was the food most associated with reduced colon cancer risk. The NCI recognizes garlic as one of the most potent cancer-preventive foods. In functional medicine, garlic is part of a cruciferous/allium-rich dietary pattern that supports Phase II detoxification and reduces lifetime cancer risk.

Metabolic Syndrome Protocol

Garlic addresses multiple metabolic syndrome parameters: blood pressure (direct reduction), lipids (cholesterol and triglyceride reduction), blood sugar (modest glucose-lowering), inflammation (NF-kB inhibition), and endothelial function (H2S-mediated vasodilation). It synergizes with berberine, cinnamon, and ginger for comprehensive metabolic support.

Four Directions Connection

Primary Direction: Serpent (South — Physical Body)

Garlic is the Serpent’s fire. It is pungent, penetrating, warming, and it burns through whatever is stagnant, toxic, or pathogenic in the body. The Serpent governs the physical body’s defense systems — the immune system, the circulatory system, the metabolic fires. Garlic activates all of these simultaneously. When infection invades, garlic is the Serpent’s first response — broad-spectrum, aggressive, and primal. When the blood thickens and stagnates, garlic moves it. When plaque builds in the arteries, garlic dissolves it. The Serpent does not negotiate with threats — it destroys or transforms them. Garlic carries this fierce, protective energy.

Secondary Direction: Hummingbird (North — Ancestral Wisdom)

No medicinal plant has been used by more civilizations, across more millennia, than garlic. From ancient Sumer to the Egyptian pyramids to the Roman legions to medieval plague doctors to modern clinical trials, garlic has been the universal medicine of humanity. The Hummingbird travels the longest journey of any medicine — and garlic’s journey spans the entire arc of human civilization. When every culture on Earth independently discovers and values the same plant, the Hummingbird is speaking: this is ancestral truth, verified across every tradition.

Tertiary: Jaguar (West — Emotional Healing)

In folklore and mythology worldwide, garlic protects against evil spirits, vampires, and malevolent forces. This is the Jaguar’s teaching in symbolic form: garlic protects the boundary between self and other, between the living and the dead, between the healthy and the pathogenic. The Jaguar guards the threshold. Garlic — both physically (antimicrobial, immune-enhancing) and symbolically (warding off harm) — serves as a guardian of the body’s boundaries. For patients who feel energetically “invaded” or “depleted” by others, garlic’s protective quality operates at both physical and psychological levels.

References

Ried, K. (2016). Garlic Lowers Blood Pressure in Hypertensive Individuals, Regulates Serum Cholesterol, and Stimulates Immunity: An Updated Meta-analysis and Review. Journal of Nutrition, 146(2), 389S-396S.
Varshney, R., & Budoff, M.J. (2016). Garlic and Heart Disease. Journal of Nutrition, 146(2), 416S-421S.
Budoff, M.J., Takasu, J., Flores, F.R., et al. (2004). Inhibiting progression of coronary calcification using Aged Garlic Extract in patients receiving statin therapy. Preventive Medicine, 39(5), 985-991.
Ried, K., Frank, O.R., Stocks, N.P., Fakler, P., & Sullivan, T. (2008). Effect of garlic on blood pressure: a systematic review and meta-analysis. BMC Cardiovascular Disorders, 8, 13.
Nantz, M.P., Rowe, C.A., Muller, C.E., et al. (2012). Supplementation with aged garlic extract improves both NK and gammadelta-T cell function and reduces the severity of cold and flu symptoms. Clinical Nutrition, 31(3), 337-344.
Amagase, H. (2006). Clarifying the real bioactive constituents of garlic. Journal of Nutrition, 136(3 Suppl), 716S-725S.
Iciek, M., Kwiecien, I., & Wlodek, L. (2009). Biological properties of garlic and garlic-derived organosulfur compounds. Environmental and Molecular Mutagenesis, 50(3), 247-265.
Fleischauer, A.T., & Arab, L. (2001). Garlic and cancer: a critical review of the epidemiologic literature. Journal of Nutrition, 131(3s), 1032S-1040S.
Lawson, L.D., & Hunsaker, S.M. (2018). Allicin Bioavailability and Bioequivalence from Garlic Supplements and Garlic Foods. Nutrients, 10(7), 812.
Benavides, G.A., Squadrito, G.L., Mills, R.W., et al. (2007). Hydrogen sulfide mediates the vasoactivity of garlic. Proceedings of the National Academy of Sciences, 104(46), 17977-17982.