Fermented Garlic: Preparation, Potential Health Benefits, and Risks

Garlic is a spice that has been used since ancient times and is known for its beneficial effects on health. It contains compounds that can help prevent and treat many diseases, such as cancer, heart disease, high blood pressure, diabetes, and metabolic disorders. Garlic works by reducing inflammation, protecting against oxidative stress (which damages cells), and lowering levels of bad fats in the blood. Numerous studies have shown that its consumption is beneficial for health and that it is safe to combine it with medications or other foods, thereby extending its therapeutic effects. Although garlic breaks down quickly in the body and is not easily absorbed in large amounts, it still has many health benefits (Ansary, et al. 2020).

The main active ingredient in garlic is allicin, which contains oxygen, sulfur, and other chemicals, giving it antibacterial properties and the ability to fight diseases (Iftikhar, 2023). When subjected to the fermentation process, garlic becomes even more valuable, and its health potential reaches a new dimension. Fermented garlic, also known as black garlic, is not only a tasty and sweet alternative to raw garlic but also provides numerous benefits for the human body. This unique food supplement helps boost immunity, lower blood pressure, improve cholesterol levels, and even fight cancer. In this article, we will explore how fermentation affects its nutritional profile, the health benefits and potential side effects, as well as how to prepare it easily at home.

What is Fermented Garlic?

Fermented (“black”) garlic is made from fresh garlic that has undergone fermentation, changing its taste and color. The fermentation process enhances the bioactivity of garlic, making it more beneficial for health. Fermented garlic is sweet and gelatinous. In addition to altering the taste, fermentation affects the minerals and nutrients in the garlic. Black garlic exhibits the following effects in the body (Mikstas, 2024):

• Antioxidant
• Antiallergic
• Antidiabetic
• Anti-inflammatory
• Anticancer effects.

The preparation process of fermented garlic is simple, although it takes 3-6 weeks:

1. Peel the garlic.
2. Place the cloves in a clean jar.
3. Add water, salt, and spices of choice.
4. Store in a cool place.
5. Let it sit for 3-6 weeks at room temperature (Mikstas, 2024).

During fermentation, the garlic cloves may turn neon green or blue, which is normal and results from a pH reaction. The cloves will likely turn white or yellow later, and the finished fermented garlic will be dark yellow. It is not recommended to open the jar to release gas unless the pressure severely bends the lid. If you do, open it slowly and gradually over 15-20 minutes. It is advised to transfer the ferment to the refrigerator once done, and a plastic lid is better than a metal one since metal may rust (Bewell Clinic, n.d.).

For health benefits, it is recommended to consume one or two cloves of fermented garlic daily, and you can gradually increase the amount if you experience symptoms of acute illnesses (Bewell Clinic, n.d.). Additionally, black garlic can be used in various dishes and as a dietary supplement. It has a mild, sweet taste compared to raw garlic, making it ideal for people who cannot tolerate its sharp flavor and smell. It can be used in salads, sauces, marinades, or simply eaten as a healthy addition to meals. Fermentation of garlic typically involves using salt, which increases its sodium content. If you make fermented garlic at home, you can control the amount of salt.

Nutritional Benefits of Fermented Garlic

• Increase in Nutrients: Fermentation increases the content of nutrients such as proteins, fats, carbohydrates, and amino acids. The highest level of proteins occurs after 60 days of fermentation, while the highest levels of fats and carbohydrates appear after 90 days.
• Antioxidant Properties: During fermentation, the content of antioxidants such as polyphenols and flavonoids increases. These antioxidants help protect the body from oxidative stress and prevent diseases related to free radicals, such as cardiovascular diseases and cancer.
• Easier Absorption of Nutrients: Fermentation makes it easier for the body to absorb nutrients since fermented garlic is less aggressive on the digestive system, making it better for people with sensitive stomachs.
• Improved Digestion: Fermented garlic contains beneficial probiotics that can contribute to gut health, improving the balance of bacteria in the intestines and aiding digestion.
• Lower Levels of Allicin: While raw garlic contains a lot of allicin, responsible for its characteristic smell and many health benefits, fermentation reduces allicin levels, making fermented garlic less pungent and aromatic. Allicin is converted into other beneficial substances during fermentation, which also have healthy effects (Mikstas, 2024).

Potential Benefits

The health benefits of garlic, which are confirmed in its fermented version, are numerous. Some of them include:

• Higher Antioxidant Levels: Fermentation increases the levels of antioxidants such as alkaloids and flavonoids, which help protect cells from damage and prevent diseases such as cardiovascular diseases and cancer.
• Boosting Immunity: Garlic can enhance the body’s immune response. It acts as an immunostimulator, increasing the number, lifespan, and strength of natural killer (NK) cells. Studies show that garlic supplements can reduce colds and shorten the duration of illnesses.
• Reducing Blood Pressure: Garlic can significantly lower high blood pressure, similar to some hypertension medications, with a daily intake of 600-1,500 mg of aged garlic extract.
• Improving Cholesterol Levels: Consuming garlic can reduce LDL (“bad” cholesterol) and total cholesterol by 10-15% in individuals with elevated cholesterol levels, but it does not significantly affect HDL (“good” cholesterol) or triglycerides.
• Detoxification of Heavy Metals: Sulfur compounds in garlic can help lower levels of heavy metals, such as lead, in the blood and reduce symptoms of toxicity, such as headaches and high blood pressure.
• Regulating Blood Sugar Levels: Animal studies show that black garlic can improve blood sugar regulation, reduce glucose and insulin levels, and lower the risk of diabetes complications. Further research in humans is needed.
• Reducing Risk of Heart Disease: Black garlic can reduce total cholesterol, LDL (bad) cholesterol, and triglycerides while increasing HDL (good) cholesterol. It also shows potential for improving heart health.
• Brain Health Protection: Black garlic can reduce inflammation affecting brain function and memory, offering protection against degenerative diseases such as Alzheimer's.
• Anticancer Properties: In preliminary studies, black garlic shows potential for fighting cancer, particularly through immune stimulation and anticancer effects in laboratory conditions. However, further research is needed.
• Liver Protection: Black garlic can help protect the liver from damage caused by toxins, medications, alcohol, and pollution. It can also contribute to improving liver function in cases of chronic damage.
• Improved Digestion: It stimulates bile production, which aids in digestion.
• Helps in Blood Thinning: It increases blood clotting time, which may help prevent the formation of clots.
• Fighting Parasites: Some types of worms cannot survive in the presence of garlic.
• Natural Remedy for Respiratory Tract: It helps reduce bronchial secretions and can be useful in treating asthma (Panoff, 2023; Mikstas, 2024; Bewell Clinic, n.d.).

Potential Side Effects

Fermented garlic generally does not have serious side effects but should be avoided in large amounts if you are taking blood-thinning medications or have an allergy to garlic (Panoff, 2023).

Garlic can sometimes be misrecognized as a threat by the immune system, triggering allergic reactions. Garlic allergy can cause symptoms such as skin inflammation, hives, itchy nose, sneezing, shortness of breath, nausea, stomach pains, and diarrhea. Symptoms can vary in intensity and may appear immediately or a few hours after exposure. If you suspect an allergy, consult your doctor, who may refer you to an allergist for testing (Mikstas, 2024).

In addition to causing allergic reactions, in larger doses, garlic can thin the blood, increasing the risk of bleeding. This can lead to negative interactions with medications such as aspirin, warfarin, and clopidogrel, as well as with the antiviral drug saquinavir, which is used to treat HIV (Iftikhar, 2023).

Conclusion

Fermented garlic, also known as black garlic, is a true natural elixir for health! Its transformation through fermentation not only improves its taste and digestibility but also increases its nutrient values and powerful antioxidants, which help in the prevention of many diseases, from cardiovascular diseases to diabetes and cancer. Its therapeutic effects, which include boosting the immune system, lowering blood pressure, improving cholesterol levels, and detoxifying the body, make it an indispensable part of a healthy diet. Although the risks are minimal, it is important to consume it in moderation, especially if you are using blood-thinning medications or have a garlic allergy. When integrated into everyday nutrition, fermented garlic can bring many long-term benefits for overall health, and its versatility in the kitchen makes it a simple and delicious addition to meals.

*This text is for informational purposes only. In case of any symptoms, it is recommended to seek advice from your doctor or a qualified healthcare professional.

References:

• Ansary, J., Forbes-Hernández, T. Y., Gil, E., Cianciosi, D., Zhang, J., Elexpuru-Zabaleta, M., Simal-Gandara, J., Giampieri, F., & Battino, M. (2020). Potential Health Benefit of Garlic Based on Human Intervention Studies: A Brief Overview. Antioxidants (Basel, Switzerland), 9(7), 619. https://doi.org/10.3390/antiox9070619
• Bewell Clinic. (n.d.). Fermented garlic: A powerful food for health. Be Well Clinic. Retrieved March 24, 2025, from https://www.bewellclinic.net/fermented-garlic-a-powerful-food-for-health/
• Anshu, A. (2020, May 12). Garlic on stainless steel bowl [Photograph]. Unsplash. https://unsplash.com/photos/garlic-on-stainless-steel-bowl-yuB68kf21Z4
• Iftikhar, N. (2023, March 27). Garlic and honey: Proven benefits, uses, recipes, and side effects. Healthline. Edited by Nastassja Myer. Retrieved March 24, 2025, from https://www.healthline.com/health/garlic-and-honey#properties
• Panoff, L. (2023, September 7). Black garlic benefits. Healthline. https://www.healthline.com/nutrition/black-garlic-benefits#How-to-add-it-to-your-diet
• Mikstas, C. (2024, December 21). Fermented garlic: Are there health benefits? WebMD. https://www.webmd.com/diet/fermented-garlic-health-benefits