Black garlic is raw garlic that people have aged under controlled high-temperature, high-humidity conditions for several weeks. The garlic cloves turn brown, then eventually black as a result of the Millard reaction (1).

In addition to having black cloves, black garlic has a milder flavor and a more delicate, sticky consistency than raw garlic (2).

Black garlic also offers a number of health benefits that may outweigh those of raw garlic, which hasn’t been aged.

This article reviews 6 of the potential health benefits black garlic may offer.

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The aging process causes black garlic to contain substantially more antioxidants than raw garlic (3).

This is partly because allicin, the compound that gives garlic its pungent odor when crushed, is converted into antioxidant compounds like alkaloids and flavonoids as black garlic ages (2, 4).

Antioxidants are compounds that help protect your cells from oxidative damage, which may otherwise lead to various diseases. People mostly consume antioxidants via plant foods, including garlic (5).

One 2014 study found that the total antioxidant activity increased significantly in black garlic during aging. In the study, garlic reached its peak antioxidant content at 21 days of aging (6).


As a result of the aging process, black garlic contains more antioxidant compounds than raw garlic. Antioxidants have protective effects against cell damage and disease.

Uncontrolled high blood sugar in people with diabetes can increase the risk of complications, including kidney damage, infections, and heart disease (7).

In a 2019 study in rats fed a diet high in fat and sugar, treatment with an extract of black garlic resulted in metabolic improvements such as lowered cholesterol, decreased inflammation and appetite regulation (8).

An older 2009 study in rats with diabetes found that aged black garlic resulted in higher levels of antioxidant activity than fresh garlic. The authors concluded that aged black garlic could help prevent diabetes complications due to its antioxidant properties (9).

In another animal study from 2019, researchers fed rats a diet high in fat. Rats that consumed black garlic experienced significantly lower levels of glucose and insulin in their blood compared with those that didn’t consume it (10).

It’s important to note that some of these results were from animal studies and that scientists need to do more studies of the effects of black garlic on diabetes and blood sugar levels in humans.


Studies have shown black garlic may help regulate blood sugar, reduce the risk of gestational diabetes, and even prevent damage from uncontrolled diabetes. Scientists need to do more research on these effects in humans, however.

Studies in animals have shown that black garlic may reduce indicators of heart disease, including levels in the blood of total cholesterol, LDL (bad) cholesterol, and triglycerides. It may also increase HDL (good) cholesterol (11).

One animal study compared the effects of raw and black garlic in rats recovering from heart damage due to ischemia — lack of blood flow to the heart.

Researchers found that both raw and black garlic helped open up circulation to protect the heart from damage (12).

Another animal study found that black garlic extract helped reduce total blood fats, triglycerides, and total cholesterol in rats fed a diet high in fat. Elevated levels of these usually indicate an increased risk of heart disease (13).

In the same animal study, black garlic lowered high triglycerides and cholesterol levels, reducing the risk of heart disease (13).

A different study gave 60 people with elevated cholesterol 6 grams of either aged black garlic extract or a placebo daily for 12 weeks. Black garlic increased HDL (good) cholesterol and reduced potential heart disease markers. However, there were no differences in triglycerides, LDL, or total cholesterol between the groups (14).

One study gave participants with coronary heart disease 20 grams of black garlic extract daily for 6 months. Those who consumed it experienced increased antioxidant levels and improved indicators of heart health compared with those who took a placebo (15).

Although animal research suggests black garlic may help reduce certain markers of heart disease, human studies are conflicting.


Black garlic may help reduce certain markers of heart disease, like triglycerides and LDL (bad) cholesterol. It may also increase HDL (good) cholesterol for some people.

Black garlic may help prevent inflammation that can impair memory and worsen brain function over time.

Scientists have suggested that inflammation of the nervous system may play a role in the development of Alzheimer’s disease (16).

One rat study found that black garlic could reduce brain inflammation caused by beta amyloid and even improve short term memory (17).

In another study, researchers induced oxidative stress in the brains of rats. Giving the rats black garlic extract prevented this oxidative stress from causing memory impairment (18).


Black garlic may contain compounds that help protect the brain from memory loss and degenerative diseases, like Alzheimer’s. However, scientists need to do more research on these potential effects in humans.

Several studies indicate a positive effect of black garlic in fighting cancer cells.

In a test tube study in the blood of 21 volunteers, black garlic extract showed stronger immune-stimulating, antioxidant, and anticancer activities than raw garlic extract (19).

In fact, the researchers found that the black garlic extract solution was toxic to lung, breast, stomach, and liver cancer cells within 72 hours (19).

One 2006 human study found that aged garlic extract (AGE) may have a suppressive effect on colorectal cancer cells (20).

However, other older human studies did not find that , researchers found that AGE did not result in any significant difference in quality of life for cancer patients, though in some cases natural killer (NK) cell count and activity improved to a degree (21, 22, 23).

This research is preliminary and scientists need to do more research on the potential cancer fighting properties of black garlic.


Black garlic has shown some potential cancer-fighting effects in test-tube studies, but more research is needed to confirm whether it can effectively help to fight cancer in humans.

Black garlic may help protect the liver from damage that can come from its constant exposure to chemicals, medications, alcohol, and germs.

Rat studies have found that black garlic exerts protective effects in the event of a liver injury, preventing further liver damage (24).

Black garlic may also be helpful in more chronic conditions. For instance, one animal study found that black garlic improved liver function in the case of chronic alcohol-induced liver damage, likely through its antioxidant activity (25).

Another study in obese rats fed a high-fat diet found that aged black garlic decreased ALT and AST, two chemicals in the blood that indicate liver damage (26).


Black garlic may have a preventive effect on the liver, protecting it from damage that can result from injury, everyday chemical exposure, or even chronic alcohol use.

Neither raw nor black garlic appear to come with major side effects. However, raw garlic has a couple of downsides that black garlic may share.

Eating raw garlic in large amounts may increase the risk of bleeding. Because of this, people on blood thinning medications may also want to avoid black garlic in large amounts (27).

That said, one study examined the effects of aged garlic extract on blood clotting among people taking blood thinning medication and found it posed no serious risk (28).

Still, it’s best to speak with a healthcare professional to determine whether black garlic is safe and appropriate for you.

Additionally, people who experience an allergic reaction after consuming raw garlic should also avoid black garlic (29).


Avoid black garlic if you have an allergy to raw garlic. You may also want to avoid it in large amounts if you take blood thinning medications. If you are concerned about taking black garlic, speak with your healthcare provider.

While you may be more familiar with raw garlic, black garlic can be a delicious addition to your diet.

Its sweet flavor and gelatinous consistency work well with a few dishes.

Here are some of the ways you can use black garlic:

  • Add it with soy sauce to make a flavorful stir fry.
  • Use it to season soups.
  • Mash it into cheese dip or cream cheese.
  • Blend it with mayo or hummus.
  • Thinly slice cloves and add them to salads or pasta dishes.
  • Use them as a topper for pizza.
  • Blend them with olive oil to make a simple salad dressing.

You may also find that you enjoy eating black garlic on its own since it’s milder than raw garlic.


Black garlic has a milder, sweeter flavor compared to that of raw garlic. You can add it to pastas, soups, or stir fries; blend it into oils; or mix it into dips and sauces.

Black garlic is raw garlic that has been aged under controlled conditions for several weeks. This changes its color and flavor.

This process also significantly increases the antioxidant activities of the garlic. In fact, antioxidants in black garlic are likely the reason for its potential benefits for the heart, liver, blood sugar, and brain, as well as its potential anticancer properties.

Black garlic doesn’t appear to have major side effects, but you should avoid it in large amounts if you take blood-thinning medications or have a garlic allergy.