Garlic Benefits: Health Properties, Uses, and Safety Precautions

Garlic (Allium sativum) is widely recognized as both a culinary staple and a medicinal plant. Used since ancient times, garlic belongs to the category of “functional foods” (alicaments)—foods that provide health benefits beyond basic nutrition.

Garlic Benefits: Health Properties, Uses, and Safety Precautions

Modern scientific research confirms garlic’s role in the prevention of cardiovascular diseases, regulation of cholesterol and blood pressure, immune support, and protection against oxidative stress. This article explores what garlic is, its composition, proven health benefits, medical uses, side effects, and precautions, based on reliable scientific and medical evidence.

What Is Garlic?

Garlic, also known as cultivated garlic, is a bulbous plant from the Amaryllidaceae family, which includes onions, leeks, chives, and shallots. Native to Central Asia, garlic spread early to Europe and the Mediterranean basin.

In Antiquity, the Greek physician Galen referred to garlic as the “theriac of peasants” due to its strengthening and protective effects. During the Middle Ages, garlic was widely used to prevent epidemics such as plague and cholera and became one of the first medicinal plants grown in monastic gardens.

Nutritional Composition of Raw Garlic

Garlic contains a wide range of bioactive compounds, including:

• Organosulfur compounds (allicin, alliin, ajoene, S-allyl cysteine, S-allyl mercaptocysteine)

• Dietary fibers, particularly inulin, a prebiotic fiber

• Polyphenols, flavonoids, and phenolic acids

• Vitamins A, B, C, and E

• Minerals and trace elements, including sulfur, potassium, selenium

• Phytosterols and prostaglandins

Prebiotic Effects

Inulin supports gut health by nourishing beneficial intestinal bacteria, especially bifidobacteria, contributing to microbiota balance.

Antioxidant Compounds

Polyphenols and sulfur compounds protect blood vessels, reduce inflammation, support cardiovascular health, and help protect the stomach lining.

Key Active Compounds in Garlic

• Alliin: Responsible for garlic’s odor; converted into allicin when garlic is crushed.

• Allicin: A powerful antioxidant, antibacterial, anti-inflammatory, and cardioprotective compound.

• S-allyl cysteine (SAC) & S-allyl mercaptocysteine (SAMC): Highly stable antioxidants, particularly abundant in aged or fermented garlic.

• Diallyl disulfide: Exhibits antihypertensive, antimicrobial, and potential anticancer properties.

To maximize allicin formation, garlic should be crushed and left to rest for about 10–15 minutes before consumption.

Health Benefits of Garlic

Anti-Inflammatory Properties

Garlic has strong anti-inflammatory, antioxidant, antiplatelet, and antifibrinolytic effects. These properties contribute to the prevention of cardiovascular diseases and metabolic syndrome.

Cardiovascular Health

Scientific studies show that garlic may help:

• Lower blood pressure

• Reduce total cholesterol and LDL cholesterol

• Lower triglycerides

• Reduce platelet aggregation

• Slow the progression of atherosclerosis

Garlic is recognized as a natural cholesterol-lowering food when incorporated into a balanced diet.

Blood Sugar Regulation

Garlic may help improve glycemic control and insulin sensitivity, making it useful as a supportive dietary component for people with type 2 diabetes.

Other Therapeutic Uses of Garlic

Garlic has been studied for its potential role in preventing or supporting treatment of:

• Certain cancers (prostate, breast, colon, stomach)

• Infections (bacterial, viral, fungal, parasitic)

• Digestive disorders and liver protection

• Gut microbiota imbalance (dysbiosis)

• Neurodegenerative diseases, including Alzheimer’s disease

• Intestinal parasites, due to its natural vermifuge properties

These effects are largely attributed to garlic’s immunomodulatory, antimicrobial, and antioxidant actions.

Recognition by Health Authorities

• ESCOP (European Scientific Cooperative on Phytotherapy) recognizes garlic for atherosclerosis prevention, lipid regulation, and respiratory infections.

• EMA (European Medicines Agency) considers garlic traditionally established for cardiovascular support and cold relief.

• WHO (World Health Organization) recognizes garlic as an adjunct treatment for hyperlipidemia and mild hypertension.

• NIH (U.S. National Institutes of Health) acknowledge moderate reductions in total and LDL cholesterol over 4–12 weeks of supplementation.

Garlic as a Dietary Supplement

Garlic supplements are derived from the bulb and may be available as:

• Powders

• Oils

• Aqueous or alcoholic extracts

• Aged or fermented garlic (black garlic)

Some extracts are standardized for active compounds such as S-allyl cysteine.

Side Effects of Garlic

At high or prolonged doses, garlic may cause:

• Stomach irritation or heartburn

• Diarrhea, gas, bloating

• Bad breath and body odor

• Altered taste of breast milk during breastfeeding

Garlic may also cause allergic reactions, including rare cases of anaphylaxis.

Risks and Drug Interactions

Garlic has anticoagulant effects, which may increase bleeding risk. Garlic supplements should NOT be used by individuals who:

• Have bleeding disorders

• Take anticoagulants or antiplatelet drugs (warfarin, aspirin, heparin)

• Are scheduled for surgery or dental procedures (stop at least 2 weeks prior)

Garlic may interact with medications for:

• High blood pressure

• Diabetes

• HIV (e.g., protease inhibitors)

• Tuberculosis

• Thyroid disorders

• Organ transplantation

• Cancer chemotherapy

• Hepatitis C treatments

Precautions and Contraindications

Garlic supplements are not recommended:

• During pregnancy and breastfeeding

• In children under 12 years

• In individuals allergic to garlic or other Amaryllidaceae plants

• In cases of gastric or duodenal ulcers

Always consult a healthcare professional before using garlic supplements, especially if taking medications.

Conclusion

Garlic is scientifically recognized for its role in:

• Preventing age-related vascular diseases

• Supporting cholesterol and blood sugar control

• Helping manage mild hypertension

• Supporting digestive, immune, and gut health

• Acting as a natural antimicrobial and antioxidant

⚠️ Garlic supplementation does not replace medical consultation or treatment.

Trusted Medical & Scientific Sources

• World Health Organization (WHO) – Medicinal Plants Monographs
  https://www.who.int

• European Medicines Agency (EMA) – Herbal Medicines
  https://www.ema.europa.eu

• National Center for Complementary and Integrative Health (NCCIH) – Garlic
  https://www.nccih.nih.gov

• PubMed – Garlic & Cardiovascular Health
  https://pubmed.ncbi.nlm.nih.gov

• MSD Manuals – Garlic Supplements
  https://www.msdmanuals.com.