Garlic is something we use to season various foods, from entrees to french fries. But one undeniable property of it is its strong smell. For those of you who love garlic but always wished it just wasn’t so pungent, here is the ideal creation: black garlic. Not only do they not leave a bad odor, but black garlic and black garlic supplements have a variety of benefits ranging from lowering cholesterol to treating high blood pressure.

What is Black Garlic?

Black garlic, which is essentially fermented or aged fresh garlic, has numerous health benefits that range from its strong antioxidant nature to its potential role in cancer treatment [1].

With its unique sweet flavor and jelly-like consistency, it is widely known in Asia for its antioxidant properties [2].

Black garlic (Allium sativum L.) is a fermented product of garlic made by treating fresh garlic for an average of 10 days at high temperatures (40 to 60 °C) and high humidity. It undergoes a Maillard reaction, which causes different compounds to form during the reaction. The reaction also darkens white garlic into a black color [3].

Processes vary widely across suppliers, with aging treatment ranging from 4 to 40 days. One study found that 21 days of treatment at 70 degrees and 90% relative humidity was best for black garlic’s antioxidant abilities [1].

While you can add black garlic to your diet, black garlic supplements are also available.


When garlic undergoes treatment to turn into black garlic, allicin, the component that gives fresh garlic its notorious odor, is converted into a variety of antioxidant compounds [R, R].

Black garlic has various antioxidants [R, R]:

  • Amadori/Heyns compounds: These are formed during the Maillard reaction. Amadori/Heyns compounds are strong antioxidants, and compared to fresh garlic, black garlic has up to 40 to 100 times more of these compounds [2].
  • 5-hydroxymethylfurfural: This is an antioxidant that also has some anti-inflammatory effects. Compared to white garlic, black garlic has a higher amount of this beneficial component, as 5-HMF is created under very high heat [4].
  • Organosulfur compounds: Diallyl sulfide, diallyl disulfide, diallyl trisulfide, and diallyl tetrasulfide [4]
  • Pyruvate: This is a key antioxidant and anti-inflammatory molecule of black garlic. It reduces nitric oxide and prostaglandin E2, both of which prolong and intensify inflammation [R, R].
  • S-allylcysteine
  • Tetrahydro-β-carbolines
  • N-fructosyl glutamate
  • N-fructosyl arginine
  • Allixin
  • Selenium
  • N-alpha-(1-deoxy-d-fructose-1-yl)-l-arginine
  • Other alkaloids, polyphenols, and flavonoids

Black garlic also contains nitrogen oxide, which has strong antiviral and antitumor effects [3].

It also contains 2-linoleoyl-glycerol, an anti-inflammatory molecule. It lowers levels of prostaglandin E2 and cytokines, which are key promoters and signals of the inflammatory response. They prolong and increase cell death, swelling, and the uncomfortable symptoms of an allergy, infection, or other sicknesses [R, R].

Mechanism of Action

Garlic contains a high abundance of hydrogen-sulfur donating compounds, which are very important for antioxidant properties to be possible. Allicin, an unstable component of garlic, is converted into organosulfur compounds, which are more stable and also contain hydrogen-sulfur donating capabilities [5].

Hydrogen-sulfur donating compounds are vital to antioxidant effects, as they activate the Nfr-2 factor [5].

Nfr-2 factors bind to antioxidant response elements, which trigger the release of various enzymes [5]:

All of these enzymes are important because they become powerful antioxidants, transforming damaging oxygens and nitrogens into nonreactive states that can significantly harm cells in the human body [5].

Health Benefits of Black Garlic

1) Has Anti-Cancer Properties

Black garlic decreases JNK and p38MAPK signaling molecules, which are heavily involved in the onset of cancer. Black garlic is toxic to a variety of cancer cells and can both stop their growth and division, and kill them. Some of these cancer cells are the A549 lung cancer cell, HepG2 liver cancer cell, and MCF-7 breast cancer cell [4].

Various cell studies have been conducted to analyze the specific anti-cancer abilities of black garlic.

May Treat Leukemia

In a study of human leukemia cells, black garlic stopped cancer cell growth. Black garlic triggered signaling molecules (caspase) to initiate programmed cell death [2].

Cell death occurs because black garlic increases the death receptor 4 and Fas ligand receptors on human cell membranes. These receptors attach to various other molecules that cause the cell to die. It also increases the number of enzymes that are vital for cell death [2].

Black garlic also degrades an enzyme called poly (ADP-ribose)-polymerase and in turn prevents DNA in cancer cells from being repaired, further ensuring that the cancer cells die [2].

May Help Treat Stomach Cancer

In a study of human stomach cancer cells, black garlic at concentrations of 10 mg/mL, 50 mg/mL, and 100 mg/mL successfully killed the cancer cells. This demonstrated black garlic’s potential role in chemotherapy [6].

In mice, black garlic treatment resulted in smaller tumors and the increase of 2 key defense enzymes (superoxide dismutase and glutathione peroxidase) in the blood. These enzymes are very important because they prevent oxidative damage and remove harmful reactive oxygen species that cause tissue damage [2].

It also reduces movement, growth, and stability of cancer cells by reducing the enzyme activity of key structural molecules called matrix metalloproteinase-2 and matrix metalloproteinase-9 [1].

May Treat Colon Cancer

Black garlic treatment led to colon cancer cell death. It also stopped the cell cycle process of growth, replication, and division [2].

Black garlic accomplishes this by stopping proteins from being made that help with cell processes, such as structure and communication. Specifically, black garlic stops a signal (phosphatidylinositol 3-kinase̸protein kinase B transduction pathway) that promotes protein synthesis and thus prevents cancer cell survival [2].

Black garlic also increased PTEN (a tumor suppressor), which prevents mutations in the DNA from accumulating that could then cause cancer [2].

Additionally, black garlic decreased the production of the genes Akt and p-Akt, both of which are thought to cause cancer if they are overactivated [2].

May Treat Endometriosis

In human endometrial cancer cells, 50 μg/mL of black garlic impeded the growth of the cancer cells by stopping important signals (c-Jun N-terminal kinase) [2].

2) Benefits the Heart

Black garlic improved the cholesterol of patients with mildly high cholesterol levels in various studies [2, 1].

In a 12-week human study (placebo) involving 60 people, 30 people were given 6 g of black garlic 2 times daily before meals. It increased HDL (good) cholesterol levels compared with the placebo group at the end of the study. However, there were no changes in LDL (bad cholesterol) [2, 1].

Black garlic’s high levels of organosulfur compounds also relax blood vessels, which leads to lower blood pressure. In a 12-week study of 79 high blood pressure patients, they took either 2 or 4 black garlic tablets daily. Their average blood pressure significantly decreased by 11.8 mm Hg [7, 8].

Black garlic also significantly decreased apo B levels in the blood. High levels of apo B are linked to heart disease [2, 1].

Black garlic also reduced fat cells, by stopping the activity of the transcription factor 3T3-L1. The transcription factors create new proteins for fact cell formation [2, 1].

3) Is a Strong Antioxidant

Black garlic reduces allicin content by converting allicin, an unstable compound, into more stable compounds that turn out to be great antioxidants. The Maillard reaction causes brown discoloration of garlic and generates various compounds that have antioxidant properties [2].

Black garlic decreased UV skin damage in mice and reduced liver damage [1].

Also, black garlic juice fed to insulin-deficient mice reduced harmful reactive substances (thiobarbituric acid) that cause damage to the blood, liver, and kidneys [1].

Black garlic is 10 times more effective than fresh garlic in its antioxidant power. The garlic mimics an enzyme (superoxide dismutase) by defending cells from hydrogen peroxide, a reactive oxygen species that can cause tissue damage [2].

4) Can Reduce Inflammation

In a human cell study, 5-HMF, an antioxidant found in black garlic, stopped the activation of nuclear factor kappa B (NF-κB) [1, 2].

This is important, as this molecule controls the release of cytokines that prolong and stimulate TNF-α activated cells [1, 2].

TNF-α activated cells promote the inflammatory response and increase blood flow, swelling, and defensive cells to the area [1, 2].

Black garlic also lowered the number of proteins that join cells and create blood clots. It also lowered the number of cells that cause inflammation and cell damage. [1, 2].

In a cell study using macrophages (immune cells), black garlic decreased the production of nitric oxide, TNF-α, and prostaglandin E2, which are all key promoters of inflammation. It accomplished this by decreasing various protein and enzyme levels, specifically of NO synthase, TNF-α, and cyclooxygenase-2 protein [1, 2].

Black garlic decreased blood clotting effects caused by platelet aggregation in both human and animal studies [1, 2].

In another mouse study, rodents were given 120 mg/kg of black garlic experienced decreased levels of cytokines TNF-α and IL-6 in the blood [1, 2].

5) Can Help Lower Severity of Allergies

Allergies are related to immunoglobulin E (IgE) antibodies and mast cells that all contribute to promoting long-term inflammation. Specifically, a type I allergy response is activated by the IgE receptor that is on the outside surface of immune cells [2, 1].

A cell study testing a 2 mg/mL treatment of black garlic resulted in a decrease of the inflammatory enzymes (β-hexosaminidase and TNF-α). This prevented an allergic response [2, 1].

In another study, 50 μg/mL of black garlic inhibited key allergy-promoting molecules (prostaglandin E2, leukotriene B4, and cyclooxygenase-2), and prevented signaling (phosphorylation of Syk, phospholipase A2, and 5-lipoxygenase) that can lead to cell attack by immune system cells called macrophages [2, 1].

Mice treated with black garlic also had a decreased allergic response visible on their skin [2, 1].

6) May Reduce Liver Damage

Rats with induced oxidative liver damage were treated with black garlic. Black garlic treatment significantly lowered markers of liver injury (AST, ALT, ALP, and LDH levels) [2].

Black garlic also increased the normal activity and metabolism of the liver as the garlic increased levels of a molecule called CYP2E1. The black garlic also decreased fatty liver deposits and rebalanced liver cell diameters to optimal size [2].

7) Can Help Reduce Obesity

In a rat study, black garlic significantly decreased bodyweight, stomach fat, and fat cell (adipocyte) size. The rats experienced the benefits of overall decreased fat. Black garlic also lowered triglyceride and LDL (bad) cholesterol levels and increased HDL (good) cholesterol levels [2].

8) May Protect Brain Cells from MSG

You’ve probably heard of the seasoning MSG (monosodium glutamate). In rat brain cells, MSG damaged the Purkinje cells in the brain (cerebellum and hippocampus) [2, 1].

The cerebellum and the hippocampus are vital parts of the brain, as they control muscle coordination and make possible human memory retention. In rats, black garlic extract helped decrease Purkinje cell damage caused by MSG [2, 1].

Supplementing with Black Garlic

Forms of Supplementation

Black garlic is taken in tablet form as supplements, or in bulb form in Asian supermarkets.

Side Effects

There are no known major side effects of black garlic. However, a toxic dose of garlic is 1,000 μg/mL. It is less toxic compared to raw garlic [9].

A rare case has been reported, in which black garlic has led to a case of pneumonia. It could not be determined if it was an immune reaction or a case of toxicity [10].

Limitations and Caveats

Various cell studies have proven the antioxidant nature of black garlic, and it is this main property that further extends to its other consequent benefits. Few extensive human clinical trials have been conducted, so it is difficult to predict the long-term effects of black garlic.

Differences Between Fresh Garlic and Black Garlic

Black garlic has increased fructose and glucose content (as a result of the Maillard reaction it undergoes under heat), explaining its sweet flavor [11].

In a cell study of immune system cells from 21 volunteers, black garlic showed stronger antioxidant and anticancer activity than fresh garlic [12].

Another study showed that black garlic is the optimal choice as an antioxidant for neutralizing reactive oxygen species. Fresh garlic, however, had stronger anti-inflammatory properties because of its lower sugar content [13].

User Experiences

Multiple users have claimed that they did not recognize any major changes, as they had not taken black garlic for a substantial period when reviewing it.

However, many remarked that they were pleased it did not have a smell and that they were taking it for its many antioxidant effects.

One user who has been taking garlic supplements regularly for years remarked that black garlic supplements seemed to be more potent. Some users felt the black garlic reduced appetite.


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