Garlic Benefits, Nutrition, and Side Effects

What is Garlic?

Garlic is a common ingredient found in almost every kitchen and recipe worldwide. But have you ever wondered how garlic benefits us beyond just adding flavour to our food?

Garlic, scientifically known as Allium sativum, belongs to the Amaryllidaceae family. It is rich in minerals, vitamins, and unique phytochemicals, including alliin and its derivative, allicin, along with saponins and flavonoids. These organosulfur compounds are responsible for garlic’s powerful, researched health properties [1], [2].

People often ask how to use garlic, what its uses are, and what health benefits it offers. Let’s explore these questions in detail.

Disclaimer: Garlic is not a substitute for medical treatment. For specific health concerns, consult a healthcare professional for personalised advice. This article is for informational purposes only and does not constitute medical advice.

Garlic Nutrition Facts

Garlic is primarily used as a spice to enhance the flavour of foods. Here are the nutritional values for approximately one teaspoon (about 3 grams) of raw garlic (based on USDA data):

Vitamins and Minerals in Garlic

A single clove of garlic provides trace amounts of essential vitamins and minerals. According to the USDA data for 100g, it contains notable amounts of Manganese, Vitamin C, Vitamin B6, and Selenium, along with smaller amounts of zinc, calcium, iron, and potassium.

Garlic Calories

A typical 3-gram garlic clove has very few calories—approximately 4 to 5 calories per clove. Because garlic is usually consumed in small quantities, it contributes minimally to your overall daily calorie intake.

Can You Eat Raw Garlic?

While garlic is traditionally sautéed, baked, or roasted, eating it raw can actually maximise its potential health benefits. Raw garlic retains higher levels of allicin, the potent sulfur-containing compound responsible for many of garlic’s researched immune and cardiovascular effects [3]. Cooking or roasting garlic significantly reduces the active allicin content, so consuming it raw may provide more potent health results.

Top Health Benefits of Eating Garlic (Lahsun)

Supports Healthy Blood Pressure

Garlic, particularly aged garlic extract, may help lower high blood pressure (hypertension) by promoting the production of nitric oxide, which helps relax and dilate blood vessels [4]. This vasodilation effect helps blood pressure return to healthy levels. Research suggests this effect is more pronounced in individuals already diagnosed with hypertension [4].

May Improve Skin Health

The antibacterial properties, primarily from allicin, may help manage skin conditions like acne by inhibiting bacterial growth (specifically Propionibacterium acnes) [5]. Garlic also has anti-inflammatory properties that may help reduce swelling. Important Note: Raw garlic should not be applied directly to the skin, as its high potency can cause severe chemical burns and irritation.

May Benefit Blood Sugar Management

Studies have shown that regular consumption of garlic, often in the form of powdered extract, may help reduce fasting blood glucose levels and improve insulin sensitivity in people with type 2 diabetes [6]. It may also help reduce spikes in blood glucose levels when taken before meals.

Supports Immune Function and May Prevent the Common Cold

Regular consumption of garlic, or garlic supplements, may boost immune function. A large-scale randomized trial suggested that a daily garlic supplement could significantly reduce the incidence of the common cold and the duration of symptoms [7]. The antimicrobial properties help the body fight off infections.

Enhances Cardiovascular Health

Garlic’s benefits for the heart are multi-faceted: it helps manage blood pressure and may lower total and LDL (“bad”) cholesterol levels [8]. Its anti-inflammatory and antioxidant properties help prevent the oxidation of cholesterol and protect against cardiovascular disease. Garlic’s anti-platelet activity can also reduce the risk of harmful blood clots [8].

Enhances Brain Function

Rich in antioxidants and sulfur compounds, garlic protects brain cells from oxidative stress and may inhibit neuroinflammation [9]. By improving blood flow and reducing inflammatory markers, it may support memory and cognitive function, potentially lowering the risk of age-related decline.

May Help with H. pylori-Related Ulcers

Garlic has demonstrated the ability to combat the Helicobacter pylori (H. pylori) bacteria, a major cause of stomach inflammation (gastritis) and peptic ulcers [10]. Its anti-inflammatory effects may also help protect the stomach lining, aiding in the healing and prevention of such issue.

Side Effects of Garlic

While garlic offers numerous health benefits, it is essential to be aware of the potential side effects, particularly with high intake or supplement use.

Common Digestive Issues:

Consuming large amounts of garlic, especially raw or on an empty stomach, can cause gastrointestinal discomfort. This includes bloating, gas, heartburn (acid reflux), nausea, or stomach upset.

Odour:

Garlic contains sulfur compounds that are excreted through the lungs and skin, which can result in strong, unpleasant breath and body odour.

Allergic Reactions:

Some individuals may be allergic or hypersensitive to garlic, experiencing symptoms such as skin rashes, itching, hives, or, rarely, breathing difficulties. Discontinue use immediately if this occurs and seek medical advice.

Increased Bleeding Risk (Drug Interaction):

Garlic is known to have anti-platelet (blood-thinning) effects [8]. This effect is a concern for individuals taking anticoagulant or antiplatelet medications (such as warfarin, clopidogrel, or aspirin) or those undergoing surgery, as it can increase the risk of bleeding.

Medication Interactions:

Garlic supplements may interfere with the metabolism and effectiveness of certain medicines, including some HIV/AIDS treatments and specific birth control pills.

Skin Irritation:

As noted above, applying raw, crushed garlic directly to the skin can cause severe chemical burns (contact dermatitis) and irritation due to its potent compounds.

Advice: Consume fresh garlic in moderation as part of a balanced diet. If you are considering high-dose garlic supplements, have existing health conditions, or are taking any medications, you must consult a healthcare professional to avoid potential adverse effects or interactions.

How Much Garlic Should You Consume?

• Recommended Intake: There is no official Recommended Dietary Allowance (RDA) for garlic. However, to benefit from its health properties, many studies use a dosage equivalent to roughly one to two cloves (approximately 3 to 6 grams) of raw garlic per day [3].
• Dietary Intake: Incorporating a diet rich in Allium family vegetables, including garlic, helps ensure you meet an effective daily amount safely.

Conclusion

Garlic is a versatile and health-promoting food with numerous evidence-backed benefits, particularly for cardiovascular and immune health. Its potency is largely attributed to allicin, released when garlic is crushed or chopped. Like any potent natural food or remedy, it should be consumed mindfully. Being aware of its potential side effects and interactions—especially its blood-thinning effect—is crucial for safe consumption. Moderation is key, and consulting a healthcare professional is recommended, especially if you have underlying health conditions or take prescription medications. With the proper precautions, garlic can be a valuable addition to your diet and wellness routine.

Expert Quote

“Garlic is a potent natural ingredient known for its extensive use in promoting heart health, boosting the immune system, and contributing to metabolic balance. The active compounds in garlic, especially allicin, play a key role in its effects by helping to reduce inflammation, manage blood pressure, and combat infections. However, it is vital to remember that a food item like garlic should be seen as a supportive measure, not a replacement for prescribed medical treatment. Individuals with medical conditions or those taking medications should consult their healthcare professional before significantly increasing their garlic intake.”

– Apoorva Sharma

Frequently Asked Questions (FAQs)

What happens if I eat garlic every day?

Eating garlic daily in moderate amounts (like 1-2 cloves) can offer numerous health benefits, including supporting the immune system, potentially lowering blood pressure, and reducing the risk of heart disease due to its antioxidant and anti-inflammatory properties [3].

What diseases does garlic help manage?

Garlic is known for its ability to support the management of various health conditions. It has been used for centuries to help mitigate symptoms of illnesses like the common cold and flu due to its antimicrobial properties [7]. Garlic also helps lower blood pressure and cholesterol levels, thereby reducing the risk factors for heart disease and stroke [8].

What is the main benefit of garlic?

The main, most well-researched benefit of garlic is its ability to improve and support cardiovascular health. Garlic helps lower blood pressure and cholesterol levels, reducing the risk of heart disease and stroke [4], [8]. It has powerful antimicrobial properties and may support infection prevention, but it is not a substitute for medical treatment.

Can too much garlic damage the liver?

While garlic is generally safe for most people when consumed in moderation, excessive intake of highly concentrated garlic supplements, rather than food amounts, has been linked to potential liver toxicity in animal studies and in rare human case reports [11]. People with existing liver conditions should exercise caution. Always stick to recommended dosages for supplements and consume food amounts in moderation.

Disclaimers: These effects are not a substitute for medical treatment. Please consult a doctor before using garlic for health concerns. The information provided is not intended to diagnose, treat, cure, or prevent any disease.

References

[1] Iciek, M., Kwiecień, I., & Włodek, L. (2009). Biological properties of garlic and garlic-derived organosulfur compounds. Environmental and Molecular Mutagenesis, 50(3), 247–265. https://doi.org/10.1002/em.20474

[2] Rivlin, R. S. (2001). Historical perspective on the use of garlic. The Journal of Nutrition, 131(3), 951S–954S. https://doi.org/10.1093/jn/131.3.951S

[3] Fejes, R., Bondonno, C. P., Radavelli-Bagatini, S., Tilman Kühn, & Wagner, K.-H. (2024). Exploring the health benefits of raw white garlic consumption in humans: a mini review. Frontiers in Nutrition, 11. https://doi.org/10.3389/fnut.2024.1459627

[4] Sleiman, C., Daou, R.-M., Antonio Al Hazzouri, Hamdan, Z., Ghadieh, H. E., Harbieh, B., & Romani, M. (2024). Garlic and Hypertension: Efficacy, Mechanism of Action, and Clinical Implications. Nutrients, 16(17), 2895. https://doi.org/10.3390/nu16172895

[5] Rios, J. L., & Schliemann, V. (2023). Antibacterial and anti-inflammatory properties of allicin and its potential use in the treatment of acne vulgaris: A review. Journal of Functional Foods, 106, 105634. https://doi.org/10.1016/j.jff.2023.105634

[6] 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). https://doi.org/10.3390/antiox9070619

[7] Lissiman, E., Bhasale, A. L., & Cohen, M. (2014). Garlic for the common cold. Cochrane Database of Systematic Reviews, (11), CD006206. https://doi.org/10.1002/14651858.CD006206.pub4

[8] Ried, K. (2016). Garlic and Cardiovascular Disease: A Critical Review. Journal of Nutrition, 146(2), 382S–389S. https://doi.org/10.3945/jn.114.202330 (New Reference added for detailed cardiovascular claims)

[9] Song, H., Cui, J., Mossine, V., Greenlief, C., Fritsche, K., Sun, G., & Gu, Z. (2019). Bioactive components from garlic on brain resiliency against neuroinflammation and neurodegeneration (Review). Experimental and Therapeutic Medicine. https://doi.org/10.3892/etm.2019.8389

[10] Kuna, L., Zjalic, M., Kizivat, T., Roguljic, H., Nincevic, V., Omanovic Kolaric, T., Wu, C. H., Vcev, A., Smolic, M., & Smolic, R. (2022). Pretreatment of Garlic Oil Extracts Hampers Epithelial Damage in Cell Culture Model of Peptic Ulcer Disease. Medicina, 58(1), 91. https://doi.org/10.3390/medicina58010091

[11] Wang, X., Chen, C., Li, J., Zou, X., Liu, Y., Lu, F., Zuo, H., & Liu, S. (2018). Toxicity and safety assessment of allicin: A comprehensive review. Food and Chemical Toxicology, 114, 148–156. https://doi.org/10.1016/j.fct.2018.02.040