Diallyl Disulfide

• Cardiovascular Health
• Antimicrobial Properties
• Antioxidant Protection
• Cancer Prevention

• Immune System Support
• Detoxification Enhancement
• Anti-inflammatory Effects
• Blood Sugar Regulation
• Liver Protection

Diallyl disulfide (DADS) exerts its biological effects through multiple mechanisms related to its organosulfur structure and reactive properties. As a key bioactive compound in garlic, DADS contributes significantly to garlic’s health benefits. In cardiovascular health, DADS inhibits HMG-CoA reductase, the rate-limiting enzyme in cholesterol biosynthesis, thereby reducing cholesterol production in the liver. It also activates AMPK (AMP-activated protein kinase), which further suppresses cholesterol and fatty acid synthesis while enhancing fatty acid oxidation.

DADS increases hydrogen sulfide (H2S) production, which acts as a gasotransmitter that relaxes vascular smooth muscle, leading to vasodilation and reduced blood pressure. It also inhibits platelet aggregation by interfering with thromboxane formation and calcium mobilization, contributing to its antithrombotic effects. As an antimicrobial agent, DADS disrupts bacterial cell membranes and inhibits bacterial thiol-containing enzymes essential for microbial metabolism. It can penetrate bacterial biofilms and shows activity against drug-resistant bacteria.

DADS’s antioxidant properties stem from its ability to induce phase II detoxification enzymes through activation of the Nrf2-Keap1 pathway, increasing the expression of glutathione S-transferase, NAD(P)H:quinone oxidoreductase, and heme oxygenase-1. This enhances cellular defense against oxidative stress and detoxification of xenobiotics. In cancer prevention, DADS induces cell cycle arrest by modulating cyclin-dependent kinases and cyclins, particularly at the G2/M phase. It triggers apoptosis in cancer cells through multiple pathways, including activation of caspases, modulation of Bcl-2 family proteins, and generation of reactive oxygen species specifically in cancer cells.

DADS inhibits histone deacetylases (HDACs), leading to epigenetic modifications that can restore the expression of tumor suppressor genes. It also suppresses angiogenesis and metastasis by inhibiting matrix metalloproteinases and vascular endothelial growth factor expression. For immune function, DADS modulates cytokine production, enhances natural killer cell activity, and regulates T-cell function. Its anti-inflammatory effects involve inhibition of NF-κB signaling and reduction of pro-inflammatory cytokine production.

In metabolic health, DADS improves insulin sensitivity by enhancing glucose uptake in peripheral tissues and protecting pancreatic β-cells from oxidative damage. It also activates PPAR-γ, a nuclear receptor that regulates glucose metabolism and insulin sensitivity. DADS supports liver function by inducing phase I and II detoxification enzymes, protecting hepatocytes from oxidative damage, and reducing lipid accumulation in the liver.

Diallyl disulfide is typically consumed as part of garlic supplements rather than as an isolated compound. The effective dose depends on the garlic preparation and its DADS content. For garlic supplements, typical doses range from 600-1200 mg of garlic powder (standardized to 1.3% alliin or 0.6% allicin potential) daily.

Diallyl disulfide is lipophilic and readily absorbed in the gastrointestinal tract. After absorption, it undergoes extensive first-pass metabolism in the liver. Bioavailability varies depending on the garlic preparation method, with oil-based extracts generally providing better absorption of DADS than powder forms.

Consumption with fatty foods increases absorption due to DADS’s lipophilic nature, Enteric-coated supplements protect DADS from stomach acid degradation, Oil-based garlic extracts provide better absorption than water-based preparations, Aged garlic extract contains more stable organosulfur compounds that may have improved bioavailability, Fermented garlic preparations may enhance bioavailability through pre-conversion of compounds, Black pepper extract (piperine) may theoretically enhance absorption through inhibition of first-pass metabolism

DADS from garlic supplements is best taken with meals to improve absorption and reduce potential gastrointestinal discomfort. For cardiovascular benefits, consistent daily use is more important than timing. For antimicrobial effects, dividing the daily dose into 2-3 servings may provide more consistent coverage. If using for blood pressure management, taking at least one dose in the evening may help with overnight blood pressure regulation.

To minimize garlic breath and body odor, taking supplements with meals and avoiding taking them before social engagements is recommended.

• Garlic breath and body odor
• Gastrointestinal discomfort
• Heartburn
• Nausea
• Vomiting (rare, at high doses)
• Diarrhea (rare, at high doses)
• Allergic reactions (rare)
• Contact dermatitis (from handling fresh garlic)

• Upcoming surgery (discontinue 1-2 weeks before due to potential bleeding risk)
• Bleeding disorders
• Garlic allergy
• Gastroesophageal reflux disease (GERD) – may exacerbate symptoms
• Inflammatory gastrointestinal conditions – may irritate the GI tract

• Anticoagulant/antiplatelet medications (warfarin, aspirin, clopidogrel) – may increase bleeding risk
• HIV medications (saquinavir and potentially other protease inhibitors) – may reduce drug levels
• Isoniazid (tuberculosis medication) – may interfere with effectiveness
• Cyclosporine – may decrease blood levels
• Contraceptive drugs – potential reduced effectiveness
• Hypoglycemic drugs – may enhance blood sugar-lowering effects
• Antihypertensive medications – may potentiate blood pressure-lowering effects

No established upper limit from regulatory bodies. Clinical studies have used up to 7.2 grams of aged garlic extract daily without serious adverse effects. Consumption equivalent to 4-5 garlic cloves daily is generally considered safe for most adults, though gastrointestinal side effects may increase at higher doses.

In the United States, DADS as a component of garlic is regulated as a dietary supplement under the Dietary Supplement Health and Education Act (DSHEA) of 1994. The FDA has not approved DADS or garlic supplements for the treatment, prevention, or cure of any disease. Garlic is Generally Recognized as Safe (GRAS) for use as a food flavoring and ingredient.

Eu: Garlic preparations containing DADS are regulated as food supplements under the European Food Safety Authority (EFSA). The EFSA has evaluated several health claims for garlic but has not approved specific claims related to cholesterol reduction or cardiovascular health due to insufficient evidence meeting their standards.

Canada: Health Canada regulates garlic supplements as Natural Health Products (NHPs). Several garlic products have received Natural Product Numbers (NPNs) with approved claims for cardiovascular health and immune support.

Australia: The Therapeutic Goods Administration (TGA) regulates garlic supplements as listed complementary medicines. Various garlic preparations are included in the Australian Register of Therapeutic Goods (ARTG) with permitted indications.

Japan: Garlic supplements are regulated as Foods with Health Claims under Japan’s regulatory system. Some products have approved functional claims related to maintaining healthy cholesterol levels.

China: Traditional garlic preparations are included in the Chinese Pharmacopoeia and are regulated as both food and traditional medicine ingredients.

Who: The World Health Organization (WHO) includes garlic in its monographs on medicinal plants, recognizing its traditional uses for cardiovascular health and antimicrobial properties.

low to medium

$0.10-$0.30 per day for fresh garlic; $0.20-$1.00 per day for garlic supplements

DADS from garlic offers excellent value compared to many other supplements targeting cardiovascular health. Fresh garlic is the most cost-effective source, with a month’s supply costing as little as $3-5, though this comes with challenges of preparation, standardization, and garlic breath. Standard garlic powder supplements are moderately priced ($6-15 per month) and offer convenience and standardized dosing. Specialized garlic preparations like aged garlic extract or odorless garlic cost more ($15-30 per month) but may provide better tolerability and reduced odor issues.

When comparing to pharmaceutical alternatives for similar conditions: garlic supplements for cholesterol management cost significantly less than statin medications, though with more modest effects; for hypertension, garlic supplements are considerably less expensive than many prescription medications, though typically less potent. The cost-effectiveness increases when considering garlic’s multiple benefits beyond cardiovascular health, including immune support and potential cancer-preventive properties. For antimicrobial effects, garlic supplements are very cost-effective compared to many commercial products, though with less targeted action. Overall, garlic and its DADS content represent one of the more cost-effective natural approaches to cardiovascular health maintenance, particularly as a preventive measure or adjunct to conventional treatments.

Pure DADS is volatile and has limited stability. In garlic supplements: Garlic powder products: 1-2 years when properly stored; Aged garlic extract: 2-3 years; Garlic oil preparations: 1-2 years if refrigerated

Store in airtight containers protected from light, heat, and moisture. Refrigeration is recommended for oil-based garlic preparations and can extend shelf life of other forms. Freezing fresh garlic can preserve active compounds including precursors to DADS. Once bottles of supplements are opened, they should ideally be used within 6 months for maximum potency.

Heat (cooking temperatures can significantly reduce DADS content), Oxygen exposure (oxidation of sulfur compounds), Light exposure (particularly UV light), Moisture (promotes enzymatic degradation), pH extremes (highly acidic or alkaline environments), Time (gradual degradation occurs even under optimal storage conditions), Microbial contamination (can accelerate breakdown of compounds)

Synthesis Methods

Natural Sources

Quality Considerations

While diallyl disulfide (DADS) itself was not specifically identified until modern times, its source – garlic (Allium sativum) – has one of the longest and most well-documented histories of medicinal use among all plants. Garlic has been used medicinally for over 5,000 years across numerous civilizations. Ancient Egyptian medical papyri from 1550 BCE mention garlic as a remedy for a variety of ailments including heart problems, headaches, bites, worms, and tumors. Workers building the pyramids were given garlic to increase their strength and endurance.

In ancient Greece and Rome, Hippocrates, Aristotle, Pliny the Elder, and Galen all prescribed garlic for various conditions including respiratory problems, parasites, poor digestion, and joint disease. Roman legionaries consumed garlic before battle for strength and courage. In ancient China, garlic was used as early as 2000 BCE for digestive ailments, respiratory conditions, and to enhance vital energy or ‘qi.’ Traditional Chinese Medicine incorporated garlic particularly for treating parasitic infections and digestive disorders. In India’s Ayurvedic medicine, garlic (or ‘rasona,’ meaning ‘lacking one taste’) was used for heart disease, arthritis, digestive disorders, and as a general tonic.

During the Middle Ages in Europe, garlic was one of the primary remedies for the plague, earning it the nickname ‘Russian penicillin.’ It was hung in doorways to ward off evil spirits and disease. Throughout history, garlic has been used across cultures for its antimicrobial properties – long before microbes were discovered. It was applied to wounds, used to preserve food, and consumed during epidemics. During World War I, garlic was used as an antiseptic for wounds when conventional medical supplies ran short.

Soldiers were given garlic juice, extract, or crushed garlic applied directly to wounds to prevent infection. The specific organosulfur compounds in garlic, including DADS, were not identified until the 20th century. In 1944, Chester J. Cavallito first isolated and identified allicin, the precursor to DADS.

By the 1980s and 1990s, scientific research began to focus on specific compounds in garlic, including DADS, and their mechanisms of action. Modern scientific interest in DADS intensified in the late 20th century with research into its potential anticancer, cardiovascular, and antimicrobial properties.

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, Silagy C, Neil A. (1994) Garlic as a lipid lowering agent–a meta-analysis. Journal of the Royal College of Physicians of London, Reinhart KM, Coleman CI, Teevan C, Vachhani P, White CM. (2008) Effects of garlic on blood pressure in patients with and without systolic hypertension: a meta-analysis. Annals of Pharmacotherapy

Studies on DADS and other garlic compounds for metabolic syndrome, Research on garlic organosulfur compounds for neurodegenerative conditions, Trials examining DADS’s potential in cancer prevention