IngredientsBlack garlic (BG) is a fermented form of garlic (Allium sativum L.), produced at precisely defined temperatures, humidities, and time periods. Allium sativum belongs to the family Alliaceae (sometimes classified within Amaryllidaceae). Black garlic is not a distinct botanical variety of garlic; rather, it is the product of a controlled thermal processing regimen applied to standard garlic bulbs.
Black garlic is a product obtained from fresh garlic (Allium sativum L.) under specific temperature and humidity conditions, and has garnered significant scientific attention due to its enhanced organoleptic qualities and superior health-promoting properties compared to the fresh product.
The aging process is often referred to as fermentation; however, this is not exactly correct. Black garlic gets its color from a chemical browning reaction, not from fermentation, charring, or any added ingredient. When whole bulbs of raw garlic are held at high temperatures and humidity for weeks, sugars and amino acids inside the cloves react with each other to produce large, dark-colored compounds called melanoidins — the same family of molecules responsible for the brown crust on bread and the dark color of coffee.
Black garlic is obtained from fresh garlic (Allium sativum L.) that has been fermented for a period of time at a controlled high temperature (60–90°C) under controlled high humidity (80–90%). The process is called the Maillard reaction, a chain of chemical events that begins when a sugar molecule bonds with an amino acid under heat. The combination of moderate heat and high moisture is essential: humidity prevents the cloves from simply drying out and hardening, while the temperature keeps the Maillard reaction moving forward continuously — this is different from roasting garlic in an oven, which would dehydrate it long before the browning could penetrate to the center of each clove.
Currently, there is no standard procedure for producing BG; processing conditions vary greatly depending on regional traditions and the specific features desired in the ultimate product. One set of investigations examined the effect of temperature on black garlic by processing it at 60°C for 69 days, 70°C for 30 days, 80°C for 15 days, and 90°C for 9 days at 80% humidity, reporting that lower temperatures over extended durations result in lower HMF formation. Black garlic is a concentrated product rich in melanoidin pigments formed as a result of the Maillard reaction under controlled conditions of high temperature and humidity (60–65°C, 80% relative humidity) for 20–30 days.
One of the most dramatic chemical shifts during transformation is in sugar content: as heat breaks down fructans, the pool of free sugars explodes, with water-soluble sugar content increasing by anywhere from 188% to 791% compared to raw garlic, while fructan levels drop by more than 84%.
Black garlic is commercially available in several forms. Black garlic can be consumed as-is, added to culinary dishes to enhance flavor, or taken in the form of dietary supplements. Black garlic powder is made by dehydrating the black garlic and then grinding it. As a supplement, it is marketed as standardized extracts (black garlic extract, or BGE), encapsulated powders, and tablets, often standardized to S-allyl-cysteine (SAC) content. Compared with fresh garlic, black garlic does not release a strong offensive flavor, owing to the reduced content of allicin.
The birthplace of black garlic is under hot debate between China, Korea, and Japan. The popular story is that black garlic was first developed in Korea as a medicine; however, it is also said to be traditional in other parts of Asia as well. One theory traces early forms of black garlic to Asia, where the bulbs were preserved using specific methods in ancient times, pointing to China, Japan, Korea, and Thailand as locations where the bulbs may have been used for medicinal or culinary purposes.
Garlic has been fermented for ages, with its origins thought to lie primarily in Korea and Japan, where the fermentation process has been used for centuries to make food more durable and digestible. Black garlic is an integral part of traditional Korean cuisine in particular, where fermented foods play a central role. The bulb was also used as a remedy in early traditional Chinese medicine, where it was believed to increase energy and promote longevity. In Taoist traditions, which place great value on the balance of yin and yang, black garlic was seen as an energetically balanced food that strengthened both the body and the mind.
In Korea, black garlic has been associated with traditional wellness tonics. In parts of China, it was sometimes used in sauces or stews. Different cultures had their own methods for making black garlic — often involving ceramic pots or sealed containers placed near hearths or in climate-controlled rooms. Some folk practices believed that black garlic had enhanced health benefits, particularly in boosting longevity and immunity.
Although garlic has been used for thousands of years, black garlic is a relatively new discovery in Western food and supplement markets. It appeared first in 1999, produced by Japanese Kamimura in Mie prefecture, Japan, who also filed a manufacturing patent for black garlic in the Japan Patent Office. A Korean inventor also claims to have come up with it in the early 2000s. In modern times, black garlic was rediscovered by the food industry in the early 2000s and gained popularity in Japan and South Korea.
The Maillard reaction, alongside other chemical transformations, converts pungent organosulfur compounds like allicin into stable, highly bioactive compounds such as S-allyl-l-cysteine and S-allylmercaptocysteine, while also increasing the levels of polyphenols and other potent antioxidants.
Black garlic is characterized by a high concentration of many antioxidant compounds, including: phenols, flavonoids, pyruvate, S-Allyl-Cysteine (SAC), S-allyl-Mercapto-Cysteine (SAMC), and 5-hydroxymethylfurfural (5-HMF). It also contains allicin-derived organosulfur compounds (OSC): diallyl sulfides (DAS), diallyl disulfides (DADS), diallyl trisulfides (DATS), and diallyl tetrasulfide.
Several studies on antioxidant properties in black garlic using DPPH radical scavenging, ABTS, Ferric Reducing Antioxidant Power (FRAP), and reducing power assays have shown increases during thermal treatment. Enzymatic and non-enzymatic reactions affect antioxidant levels of black garlic.
Analysis of black garlic (BG) and black garlic extract (BGE) has indicated that S-1-propenyl-l-cysteine (S1PC) contents vary widely (2.24–16.58 mg/100 g in BG and not detected to 3.68 mg/100 mL in BGE). Based on the significance of these compounds, standardization of the SAC and S1PC content in commercial BGE products is required. Challenges persist in obtaining a product with consistent qualitative characteristics and biological effects, primarily due to the lack of a standardized manufacturing method.
The allyl group of SAC is necessary to preserve scavenging activities, such as scavenging superoxide anion, hydrogen peroxide, hydroxyl radical, and peroxynitrite anion.
According to research, the anti-inflammatory effect is mainly due to the reduction in the production of pro-inflammatory cytokines, as well as the ability to scavenge free oxygen radicals and induce apoptosis. The bioactive organosulfur compound SAC has been shown to exert anti-inflammatory effects by modulating the nuclear factor-kappa B (NF-κB) pathway, which regulates the expression of pro-inflammatory cytokines. Several compounds in black garlic could have anti-inflammatory effects, including pyruvate, S-Allyl-Cysteine (SAC), 2-linoleoylglycerol, and 5-hydroxymethylfurfural (5-HMF).
Black garlic has been shown to significantly reduce blood sugar levels, lipid peroxidation, and enhance antioxidant defenses by activating downstream nuclear factor erythroid 2-related factor 2 (Nrf2) and Nrf2 targets such as quinone-oxidoreductase-1 (NQO1), heme oxygenase-1 (HO-1), and glutathione S-transferase alpha 2 (GSTA2).
Two amadori compounds in black garlic extract, specifically Fru-Arg and Fru-Met, were probably attributed to ACE inhibitory activity. ACE inhibitory effects of black garlic extract were found to be greater (88.8%) than normal garlic extract (52.7%) in one study.
The phytochemicals contained in black garlic have antiproliferative and antiangiogenic properties and inhibit the growth of cancer cells. Anticancer effects may affect cancer cells by modulation of many pathways including alteration in carcinogen-metabolizing enzymes, cell cycle arrest, and induction of apoptotic cell death and suppression of oncogenic signal transduction pathways.
SAC has demonstrated the ability to mitigate oxidative damage and improve neurological deficit in rat models of focal cerebral ischemia. SAC treatment significantly reduced ischemic lesion volume, suppressed neuronal loss, inhibited glial fibrillary acidic protein, and inducible nitric oxide expression. SAC also ameliorated rat cognitive impairment through reduced acetylcholinesterase activity, neuroinflammation, astrogliosis, and oxidative stress.
Black garlic shows a high concentration of organosulfur compounds, which have been related to benefits in the prevention or delay of cardiovascular diseases (CVDs). However, clinical trial evidence specifically for black garlic is limited and mixed.
A study among 55 men and women in the Republic of Korea with borderline-high LDL cholesterol (average 150 mg/dL) found that 6 g/day of aged black garlic extract (providing 780 mcg SAC, no allicin) for three months slightly increased HDL cholesterol but did not decrease LDL cholesterol, total cholesterol, or triglycerides compared to placebo (Jung, Nutrition, 2014).
A study in Spain among 61 people (average age 53) with high cholesterol (LDL ≥115 mg/dL) found that 250 mg/day of aged black garlic extract (standardized to 1.25 mg SAC) for six weeks did not improve cholesterol or triglyceride levels compared to placebo.
In a before-and-after controlled study, the intervention consisted of the ingestion of 4 cloves of black garlic (12 g) daily for 12 weeks. Significant increases in Apolipoprotein A1 occurred in both hypercholesterolemic and healthy groups. Significant reductions for endothelial adhesion molecules monocyte chemoattractant protein-1 (MCP-1), intracellular adhesion molecule-1 (ICAM-1), and vascular cyto-adhesion molecule-1 (VCAM-1) were observed. These data suggest that black garlic consumption could improve some parameters related to endothelial function and lipid profile, which may have a favorable impact on CVD risk, although more long-term studies are necessary to confirm.
For aged garlic broadly (not exclusively black garlic), a 2025 systematic review and meta-analysis of 19 randomized controlled trials found: aged garlic consumption significantly reduced systolic blood pressure (WMD: −2.49 mmHg; 95% CI: −4.02 to −0.95) and LDL (WMD: −4.41 mg/dL; 95% CI: −8.28 to −0.54). However, it did not significantly affect diastolic blood pressure and HDL, although the effect on total cholesterol approached significance (WMD: −4.74 mg/dL; 95% CI: −9.49 to 0.01). Further high-quality trials are needed to confirm these findings. It should be noted that many trials in this meta-analysis used aged garlic extract, which partially overlaps with but is not identical to what is currently marketed as black garlic.
In vivo studies on the effect of black garlic specifically on a population at cardiovascular risk are scarce, compared to raw garlic.
One study aimed to validate the antihypertensive effects of an optimized extract of aged black garlic with low doses of SAC in a Grade I hypertensive population with drug treatment. A randomized, triple-blind, placebo-controlled parallel trial was developed, where a daily supplementation with 0.25 mg/day of SAC for 12 weeks was performed. A reduction in systolic and diastolic blood pressure of 1.8 mmHg (95% CI: 0.7 to 4.1) and 1.5 mmHg (95% CI: 0.3 to 3.0), respectively, was observed. Similarly, an increase in blood nitric oxide and antioxidant capacity and a reduction in uric acid levels and ACE activity were observed. No changes in endothelial function and inflammatory cytokines were observed. The blood pressure reductions observed, while statistically significant, were modest in absolute terms.
Much of the published evidence for black garlic's antioxidant and anti-inflammatory properties comes from in vitro and animal studies. Although animal studies suggest black garlic may have anti-inflammatory, antioxidant, and potentially anti-cancer effects, human clinical evidence is limited. In experimental models, black garlic has demonstrated reduced production of pro-inflammatory cytokines including TNF-α, IL-6, and IL-1β, mediated principally through the NF-κB pathway and Nrf2 activation. A clinical trial on 51 healthy adults for 6 weeks investigated the effect of aged garlic extract on chronic inflammation and immune function in adults with obesity. A daily dose of 3.6 g aged garlic extract prevented the increase of serum TNF-α and IL-6, and reduced the levels of blood LDL in adults with obesity. This trial used aged garlic extract rather than thermal-processed black garlic specifically.
Although the beneficial effects of garlic intake against cancer have been reported in animal studies, benefits in human studies still remain controversial. For black garlic specifically, the evidence base is even more preliminary. In vitro studies of aged black garlic extracts have shown the inhibition of thyroid cancer cell lines and lung cancer Lewis cells. The anticancer effects of aqueous extract of aged garlic on diethylnitrosamine (DEN)-induced liver cancer in rats were observed. Administration of this extract for 7 weeks resulted in a reduction in liver mass, with significant reductions in the levels of alanine aminotransferase (ALT), aminotransferase (AST), and total bilirubin, and an increase in antioxidant activity — emphasizing its hepatoprotective and antioxidant effects in rats with DEN-induced liver cancer.
At this time, no human randomized controlled trials have demonstrated anticancer efficacy of black garlic as a stand-alone intervention. The available data are confined to cell culture and animal models.
The mechanism of hepatoprotective compounds is usually related to antioxidant or anti-inflammatory effects. Black garlic is produced from garlic by heat treatment and its anti-inflammatory activity has been previously reported. Investigations have focused on the hepatoprotective effect of black garlic extracts against carbon tetrachloride (CCl₄)-induced acute hepatic injury. Many studies have shown that garlic has numerous beneficial effects including antioxidant, anti-inflammation, anti-cancer, lipid regulation, reduction of blood pressure, and improvement of blood glucose control. Additionally, garlic and its derivatives exhibit hepatoprotective effects against alcoholic hepatic injury, drug-induced hepatic injury, and fibrogenic liver disorders. Evidence for hepatoprotective effects of black garlic in humans is currently lacking; the data are predominantly from animal models.
BG extracts have been reported for their activity in reducing body weight, adipose tissue mass, serum triglyceride, total cholesterol, low-density lipoprotein, and plasma malondialdehyde in mice with high-fat-diet-induced obesity. Some studies have been published on the beneficial role of aged black garlic in improving the lipid profile and insulin sensitization in an obesity and/or diabetes context, both in experimental animals and in humans. However, the mechanisms by which aged black garlic exerts these effects are poorly understood. Large-scale human trials are lacking, and evidence specific to black garlic (as opposed to garlic or aged garlic extract broadly) is preliminary.
Neuroprotective properties of black garlic and its constituent SAC have been explored primarily in preclinical models. Research has provided evidence that Chilean Elephant Black Garlic confers neuroprotection against the toxicity of soluble oligomers of amyloid-beta (SO-Aβ), a central pathogenic element of Alzheimer's disease (AD) known to trigger synaptic dysfunction and mitochondrial impairment. In mouse hippocampal slices, BG prevented SO-Aβ-induced reductions in cell viability. Complementary experiments in cultured hippocampal neurons showed that BG preserved spontaneous calcium signaling and prevented SO-Aβ-mediated alterations in neuronal arborization. At the molecular level, BG restored the expression of synaptic proteins (SV2 and PSD-95) and maintained BDNF levels. Beyond synaptic protection, BG also preserved mitochondrial function under SO-Aβ challenge by maintaining mitochondrial membrane potential, intracellular ATP levels, and Mitofusin-1 expression.
Both aged garlic extract and SAC have shown the ability to induce neuroprotection by controlling reactive oxygen species (ROS). This effect was related to their antioxidant ability in increasing the mRNA expression levels of glucose transporter 3 and glutamate-cysteine ligase catalytic subunit in rats with transient focal cerebral ischemia. All reported evidence remains at the in vitro and animal model stage; no human clinical trials have specifically examined the neuroprotective effects of black garlic.
Garlic and its bioactive constituents have been shown to have many properties in in vitro or in vivo studies, including antibacterial and antifungal activities. Black garlic retains organosulfur compounds with demonstrated in vitro antimicrobial potential; however, human clinical trials specifically testing antimicrobial properties of black garlic are absent from the published literature.
Black garlic extensively discussed biological activities include immunostimulatory effects. The evidence is mostly derived from animal and in vitro studies, with limited human data. Black garlic extracts can boost immunity based on experimental models; robust human trial data specifically characterizing immune outcomes for black garlic are currently lacking.
Based on the accumulated preclinical and emerging clinical evidence, black garlic and its bioactive constituents have been studied in relation to the following body systems:
Scientific research highlights the anti-cancer, anti-proliferative, anti-inflammatory, immunomodulatory, cardioprotective, nephroprotective and hepatoprotective properties of black garlic, its protective effects on the digestive system and nervous system, and its anti-diabetic and anti-obesity properties.
The following dosages have been specifically reported in published studies; they are not recommendations:
There is no universally established or pharmacopeially standardized dose for black garlic as a dietary supplement. The wide variation in preparation methods, SAC concentrations, and product formulations makes direct dose comparisons across studies difficult.
Compared to Allium sativum, black garlic has fewer side effects and is easier to consume. Black garlic does not release a strong offensive flavor owing to the reduced content of allicin. Data from clinical studies and spontaneous adverse event reporting schemes indicate that adverse events following garlic supplementation are mild and reversible. The most frequent events were body odour and gastrointestinal upsets.
Garlic usually has no harmful effects other than making the breath, body, and breast milk smell like garlic. However, consuming large amounts can cause nausea and burning in the mouth, esophagus, and stomach.
Garlic consumption is accompanied by an unpleasant odor from the mouth and body. There is evidence that garlic consumed in large doses has toxic effects. Additionally, a significant number of consumers have stopped consuming garlic due to gastrointestinal discomfort, including damage to the stomach and intestinal walls. The thermal aging process substantially reduces allicin content, which is the primary source of the pungency and much of the gastric irritation associated with raw garlic, making black garlic generally better tolerated.
There were isolated case reports of garlic supplements causing increased bleeding during surgery. The data available seem to indicate that garlic is a safe supplement with the caveat that it should be contraindicated prior to surgery or for patients on blood-thinning agents. Taking black garlic supplements may have an impact on the efficacy of substances with anticoagulant effects, as black garlic may increase the risk of bleeding.
Garlic supplements may reduce cyclosporine blood levels through CYP3A4 induction, potentially compromising immunosuppression in transplant recipients. Garlic preparations may decrease the effectiveness of birth control drugs; the mechanism is believed to involve CYP enzyme induction affecting hormone metabolism.
Garlic may interact with medications used to treat HIV infections (such as saquinavir), making them less effective, and may interact with medications that decrease blood sugar levels, causing excessive decreases in blood sugar. Garlic can also add to the effects of blood pressure-lowering medications and thus lower blood pressure too much.
There is no strong evidence of significant interactions between garlic supplements and statins (rosuvastatin, atorvastatin) in humans. Some animal studies have suggested potential pharmacokinetic alterations at high doses, but human data indicate limited or no clinically relevant interactions.
Small amounts of garlic that may be eaten as part of the diet are unlikely to cause drug interactions.
Most safety data for black garlic as a distinct product is extrapolated from the garlic and aged garlic extract literature. There are few long-term, large-scale clinical trials specifically assessing the safety profile of commercially produced black garlic preparations. Challenges persist in obtaining a product with consistent qualitative characteristics and biological effects, primarily due to the lack of a standardized manufacturing method, which also complicates safety characterization across products.
The preponderance of available evidence for black garlic's biological activity derives from in vitro cell-culture studies and animal models. Human clinical trial data are available for a narrow range of endpoints — primarily blood pressure and lipid profiles — but are characterized by small sample sizes, short study durations, and heterogeneous preparations. In vivo studies on the effect of black garlic on a population at cardiovascular risk are scarce, compared to raw garlic. Further research involving larger sample sizes, extended follow-up periods, and enhanced methodological rigor is essential to draw definitive conclusions about any specific health application. Current reviews highlight black garlic's potential as a functional food and source of therapeutic agents, while also emphasizing the need for standardized production methods to ensure consistent quality and maximize its health benefits.
Health conditions that Black garlic may help support.
Black garlic (fermented/aged garlic) has amplified antioxidant activity compared to fresh garlic due to Maillard reaction-generated bioactives including S-allylcysteine, melanoidins, and fructooligosaccharides. Human RCTs demonstrate black garlic extract reduces oxidative stress, improves lipid profiles, and has greater anti-inflammatory effects than fresh garlic relevant to healthy aging.
Body systems that Black garlic may help support.
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