Health Benefits Of Garlic

What is garlic?

One of the oldest cultivated plants in the world, garlic (Allium sativum) is commonly used as a culinary spice. However, this culinary spice has been used to prevent and treat a variety of conditions and diseases.

Garlic has been used worldwide for thousands of years. Records show that garlic was already there when the Pyramids of Giza were built, which is about 5,000 years ago. Richard S. Rivlin wrote in the Journal of Nutrition that the ancient Greek physician Hippocrates (460-370 BC), now known as "the Father of Western Medicine," prescribed garlic for a variety of conditions and diseases. Hippocrates encouraged using garlic as a treatment for respiratory problems, parasite infections, indigestion, and general weakness.

Other members of this family are onions, leeks, chives, and shallots. Garlic is characterised by its stimulating aromas and unique taste. The bulb is the most commonly used part of the garlic plant and usually consists of 8 to 20 individual teardrop-shaped cloves surrounded by a white paper-like skin. Dried garlic can be sold loose, in bunches, or plaited into strings; in general, the smaller the bulb, the stronger the flavour.

Significant facts about garlic:

  • Garlic has been utilised medicinally in many countries for centuries
  • Garlic is extremely beneficial for health: whether raw or cooked
  • It can have important antibiotic properties

Health benefits of garlic

Below are listed scientifically proven examples indicating the benefits of garlic.

  • Garlic contains compounds that are anti-inflammatory

Much of garlic's therapeutic appeal is due to an active ingredient called allicin.1 This sulphur-containing compound gives garlic its pungent odour and distinctive flavour. As chopping and shredding stimulates the production of allicin it's best to add the garlic late in the process. Even though allicin gives a distinctive flavour to food, it has been found that allicin has antiviral and antibacterial properties, effective against a broad range of bacteria including multidrug-resistant strains of E. coli.1 In addition, allicin had antifungal properties, including against Candida albicans, which causes yeast infections.1 Therefore, garlic could be a potential antibacterial, antifungal, and antiviral medicine.

  • Garlic may reduce the risk of heart disease

Stroke and heart attack are two of the most serious health problems in the world. Hypertension, or high blood pressure, is considered a major contributor to heart disease. Approximately 70% of strokes, heart attacks, and chronic heart failure are caused due to high blood pressure which is a major contributor to approximately 13.5% of deaths worldwide.2

Academic studies have focused on garlic's potential to help reduce the risk of heart disease and control cholesterol levels.3 It has been suggested that garlic reduces the likelihood of blood clotting; this means that garlic can act as an anticoagulant (a medicine that prevents blood clots) and reduce the risk of heart attack.3

  • Garlic may have anti-cancer properties

Sulphur-containing compounds in garlic have been studied for their ability to suppress cancer cell activity and inhibit tumour growth.4 Although much of the evidence is observational, only a small number of subjects were included in the studies. As a result, the effects of garlic on cancer remain uncertain and require further research.3 

Organosulfur compounds found in garlic have been shown to be effective in destroying the cells of glioblastoma, a type of deadly brain tumour.5 In addition, a study conducted at the Jiangsu Provincial Center for Disease Control and Prevention in China found that people who ate raw garlic at least twice a week during the seven-year study period had a 44% reduced risk of developing lung cancer.6

  • Garlic has antimicrobial and antifungal properties

Garlic has long been used to fight infections against viruses, bacteria, and fungi.1 Some skin conditions, such as insect bites, may also respond to garlic oil or crushed cloves of raw garlic.

According to a study published in the Journal of Antimicrobial Chemotherapy, diallyl sulphide, a compound found in garlic, was 100 times more effective than two common antibiotics in fighting Campylobacter.7 The bacterium Campylobacter jejuni is one of the most common causes of intestinal infections.7

  • Garlic may support bone health

Animal studies suggest that garlic may minimise bone loss by increasing oestrogen levels in female rodents.8 A similar effect was seen with a daily dose of dried garlic extract (equivalent to 2g of fresh garlic) in a study in postmenopausal women.9 Research also suggests that garlic supplements can reduce the inflammatory symptoms of osteoarthritis (a condition that causes joints to become painful and stiff).10

  • Garlic may improve blood pressure

As mentioned before, garlic can be a great spice to include in your diet if you suffer from high blood pressure. But even if you're not a garlic lover, taking garlic supplements can provide health benefits like lowering high blood pressure, and more.

It has been found that garlic also has beneficial properties that involve improving blood pressure.2 Garlic can lower blood pressure since it is capable to widen blood vessels and thus allowing blood to flow more freely.2

However, to guarantee that you make the most of the benefits of garlic, you have to make sure that the amount of the supplemental intake is equivalent to 4 cloves of garlic per day.

  • Garlic can boost the immune system

Your body's immune response is responsible for preventing you from getting sick in the first place and fights sickness when the situation calls for it. Garlic boosts your immune system and helps fight colds and other infections.

A child catches a cold 6-8 times a year whereas an adult 2-4 times. To improve this, garlic consumption can protect you from coughs, fevers, and colds.11 In some homes around the world, families string garlic cloves around their children's necks to help with congestion.

  • Garlic can help with cholesterol levels 

Cholesterol is a fatty component in the blood. There are two types of cholesterol:

"Bad" LDL Cholesterol and "Good" HDL Cholesterol. Excessive LDL cholesterol or low HDL cholesterol can cause severe health problems. It has been identified that garlic can lower total cholesterol, triglyceride, and LDL levels while improving HDL levels.3 If you have a family history of heart disease or are suffering from heart disease, you should consider adding garlic to your diet.

  • Alcohol-induced liver injury

Alcohol-induced liver injury is caused by long-term excessive consumption of alcoholic beverages. Scientists at the Institute of Toxicology, Faculty of Public Health, Shandong University, China, wanted to determine whether diallyl disulfide (DADS), an organosulfur compound derived from garlic, has a beneficial effect against ethanol-induced oxidative stress. The researchers concluded that DADS may help prevent ethanol-induced liver injury.12

Nutritional facts

One clove (4g) of garlic contains:

  • 4 Kcal / 16KJ
  • 0.3 g protein
  • 0 g fat
  • 0.7 g carbohydrates
  • 0.2 g fibre
  • 25 mg potassium

Side effects and other concerns

Garlic has few safety issues and allergies are rare. If you are taking garlic supplements for cholesterol control, check your cholesterol levels after 3 months. The recommended daily amount of garlic ranges from ½ - 1 whole clove per day (around 3000-6000 mcg of allicin). However, garlic can reduce blood clotting, so you should stop eating it 7-10 days before any scheduled surgery. In addition, be aware that some people experience indigestion, gas, or diarrhoea when taking high doses of garlic. 


To summarise, garlic may be more than just a spice used in cooking. This article highlights garlic as a potential candidate for the prevention and treatment of a variety of health conditions. The effects of garlic administration including the anti-inflammatory, antimicrobial, and lipid-lowering effects are summarised.


  1. Ankri S, Mirelman D. Antimicrobial properties of allicin from garlic. Microbes and Infection. 1999 Feb 1;1(2):125–9. Available from:
  2. Ried, K. (2019). Garlic lowers blood pressure in hypertensive subjects, improves arterial stiffness and gut microbiota: A review and meta-analysis. Experimental and Therapeutic Medicine. Available from:  
  3. 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, 9(7), 619. Available from: 
  4. Petrovic, V., Nepal, A., Olaisen, C., Bachke, S., Hira, J., Søgaard, C., Røst, L., Misund, K., Andreassen, T., Melø, T., Bartsova, Z., Bruheim, P., & Otterlei, M. (2018). Anti-cancer potential of homemade fresh garlic extract is related to increased endoplasmic reticulum stress. Nutrients, 10(4), 450. Available from:  
  5. Das A, Banik NL, Ray SK. Garlic compounds generate reactive oxygen species leading to activation of stress kinases and cysteine proteases for apoptosis in human glioblastoma T98G and U87MG cells. Cancer. 2007 Sep 1;110(5):1083–95. Available from:
  6. Jin ZY, Wu M, Han RQ, Zhang XF, Wang XS, Liu AM, et al. Raw garlic consumption as a protective factor for lung cancer, a population-based case–control study in a chinese population. Cancer Prevention Research. 2013 Jul 1;6(7):711–8. Available from:
  7. Lu, X., Samuelson, D. R., Rasco, B. A., & Konkel, M. E. (2012). Antimicrobial effect of diallyl sulphide on campylobacter jejuni biofilms. Journal of Antimicrobial Chemotherapy, 67(8), 1915–1926. Available from:
  8. Mukherjee, M., Das, A. S., Mitra, S., & Mitra, C. (2004). Prevention of bone loss by oil extract of garlic(allium sativum Linn.) in an ovariectomized rat model of osteoporosis. Phytotherapy Research, 18(5), 389–394. Available from:  
  9. Mozaffari-Khosravi, H., Hesabgar, H.-al-S., Owlia, M.-B., Hadinedoushan, H., Barzegar, K., & Fllahzadeh, M. H. (2012). The effect of garlic tablets on pro-inflammatory cytokines in postmenopausal osteoporotic women: A randomised controlled clinical trial. Journal of Dietary Supplements, 9(4), 262–271. Available from:  
  10. Dehghani, S., Alipoor, E., Salimzadeh, A., Yaseri, M., Hosseini, M., Feinle-Bisset, C., & Hosseinzadeh-Attar, M. J. (2018). The effect of a garlic supplement on the pro-inflammatory adipocytokines, Resistin and tumour necrosis factor-alpha, and on pain severity, in overweight or obese women with knee osteoarthritis. Phytomedicine, 48, 70–75. Available from:
  11. Lissiman E, Bhasale AL, Cohen M. Garlic for the common cold. Cochrane Database Syst Rev. 2014 Nov 11;2014(11):CD006206. Available from:
  12. Zeng T, Zhang CL, Song FY, Zhao XL, Yu LH, Zhu ZP, et al. The activation of HO-1/Nrf-2 contributes to the protective effects of diallyl disulfide (Dads) against ethanol-induced oxidative stress. Biochimica et Biophysica Acta (BBA) - General Subjects. 2013 Oct 1;1830(10):4848–59. Available from:
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Karina Silova

MSc Molecular Medicine and BSc Biomedicine, University of East Anglia, UK

My background is in key areas of biomedical research focusing on diseases and their molecular pathways to understand their root cause. I specialise in epigenetics and reproductive health; I am passionate about understanding diseases and helping to bridge the gap between medical science and the general public with accurate and understandable content while educating the public about health and diseases.

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