7 Garlic Benefits: Dosage & Safety

Garlic is an herb that is well-known for its heart health benefits and antimicrobial properties. It has been used throughout history as food. In traditional Chinese and Indian medicine, garlic …

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Written by: Siobhan Mendicino
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Medical Review by: Daniel Powers, MS
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Garlic is an herb that is well-known for its heart health benefits and antimicrobial properties. It has been used throughout history as food.

In traditional Chinese and Indian medicine, garlic was used for many health complaints, including indigestion, infectious diseases, and parasitic infestations. 

Modern research shows that garlic and its active constituents may be beneficial for heart health, reducing inflammation, diabetic symptoms, and as a natural antibiotic. 

In this article, we will look at the health benefits of garlic, its safety, and its history.  

the benefits of garlic

Table of Contents

What is Garlic?

Garlic is a perennial plant that belongs to the Amaryllidaceae family and is native to central Asia, although it is now found all over the world. Garlic’s Latin name is Allium sativum. 

The most common part of the plant that is used is the bulb, however, the leaves carry culinary and medicinal value as well. The bulb grows underground and is made up of multiple cloves that provide the plant with nutrients. 

Garlic cloves have an iconic, potent odor. It is warming and stimulating to the body and has been popular as a food and medicine for millennia.

Modern research supports the traditional claims that garlic has antioxidant, anti-inflammatory, and diabetes-supporting effects. Research also shows that garlic can help protect the liver. 

Many of these various therapeutic benefits of garlic can be attributed to the array of phytochemical compounds present in the clove, including: 

  • Allicin
  • Alliin
  • Allyl propyl disulfide
  • Ajoene
  • Diallyl trisulfide
  • S-allyl cysteine
  • Vinyldithiins

Garlic also contains high levels of phosphorus, zinc, and potassium.

Presently, garlic is cultivated all over the world and is seen as comparable to some modern prescription drugs

Health Benefits of Garlic:

Garlic is a well-researched herb with many human clinical trials backing it. Many of its traditional uses have been scientifically tested and show promising results. 

Below are the top researched-backed garlic benefits for health.

health benefits of taking garlic

1. Antimicrobial Properties

Evidence shows that garlic may have promising effects for treating fungal infections and fighting bacterial growth.

Infection occurs when bacteria, viruses, fungus, or other microbes infiltrate the body. During an infection, the immune system responds by attacking foreign invaders. 

In a comparative trial involving children, garlic showed promise for preventing acute respiratory disease. The tablets were able to prevent infection at a higher rate than the common pharmaceutical drug, Benzimidazole. 

A clinical trial involving 110 women found that garlic tablets (Garcin®) were similarly effective as a common pharmaceutical in treating Candida vaginitis. After 7 days of therapy, symptoms improved by 60% in the Garcin® group and 73% in the pharmaceutical group. 

Researchers discovered that garlic has a promising effect on chronic oral candidiasis (i.e. mouth infections) in comparison to common drugs. Participants saw significant recoveries in both the garlic and drug group, however, subjects mentioned greater satisfaction when given the garlic therapy.    

In a 2017 study, a mouthwash blend of garlic, green tea (Camellia sinensis), and lime was shown to significantly reduce oral bacterial load in children. This mouthwash combination was found to be as effective as a sodium fluoride mouth rinse. 

An isolated constituent of garlic, ajoene, was found to have 100% efficacy when treating athlete’s foot. The ajoene was applied topically in a gel and prevented any reoccurrence of the fungal infection 60-days after the last treatment. 

Summary:

Clinical research, along with traditional knowledge, indicates that garlic has strong antimicrobial properties.

2. May Support Heart Health

Clinical research, as well as traditional evidence, shows that garlic is an herb that may benefit heart health.

Heart disease can develop from a number of complications such as high blood pressure, diabetes, obesity, and diet. It’s one of the leading causes of death in the United States.

In a study including patients with mild hypertension, garlic was able to reduce blood pressure levels. Researchers also saw a reduction in LDL cholesterol (i.e. “bad” cholesterol) levels after 8 weeks of administration. 

In another trial involving subjects with hypertension, garlic powder was found to reduce blood pressure levels by 10-12 mmHg. However, researchers note that these levels can not be considered significant as they fall within the known variability for blood pressure measurements. 

A study involving subjects with elevated cholesterol levels found that aged black garlic shows promise for reducing biomarkers that lead to plaque in the arteries. These results conclude that aged black garlic may be helpful for preventing and protecting against heart disease.

In a trial including type 2 diabetic individuals, 12 weeks of garlic administration significantly reduced LDL cholesterol levels. The garlic supplement was also able to increase the levels of good cholesterol, reducing the risk of diabetes-related heart problems.  

Summary:

Clinical research suggests that garlic extract may help to support heart health by lowering blood pressure and reducing LDL cholesterol levels. Additional large-scale trials are needed to verify these findings.

3. Anti-Inflammatory Properties

Garlic has been used in both traditional and modern medical practices for its anti-inflammatory properties.  

Inflammation is a biological response mediated by the immune system. It supports the body’s immune system when exposed to trauma, toxins, infection, and physical overuse. Short-term or acute inflammation is necessary for physiological recovery, however, chronic inflammation can lead to a number of health complications over time. 

Researchers found that aged garlic extract showed promise for balancing out inflammatory markers in obese individuals. After 6-weeks of administration, garlic extract modulated the immune system’s inflammatory response and reduced LDL cholesterol in the blood.  

In a study involving patients with peritoneal dialysis (a treatment for kidney failure), garlic extract administered twice a day for 8 weeks significantly reduced inflammatory markers. There were no adverse side effects, and researchers found this to be a safe natural substance for preventing life-threatening inflammation in patients with peritoneal dialysis.

A trial with healthy subjects found that aged garlic extract supplementation was potentially effective for reducing flu inflammation symptoms. The extract was able to increase immune cell function and modulate the immune response resulting in less severe symptoms. 

In a trial involving women at low risk for heart disease, aged garlic extract was able to reduce levels of inflammatory markers and blood pressure levels. Researchers noted this effect after 12 months of supplementation. 

Summary:

Research shows that garlic may help to reduce inflammation in the body.

4. Anti-Diabetic Properties

Research shows that garlic benefits individuals with diabetes. In fact, it’s thought to be a key herb for blood sugar management.

Diabetes is considered a chronic metabolic disorder with the common symptom of elevated blood sugar levels. This occurs due to the body’s compromised relationship with insulin which can lead to long-term organ damage and disease. 

A comparison study found that a common diabetes pharmaceutical, Metformin, taken along with a garlic tablet had more effective results for type 2 diabetes patients than taking the drug by itself. The drug plus garlic significantly reduced blood glucose levels as well as other diabetes markers. 

Another trial with type 2 diabetes patients found that a time-released garlic powder tablet, Allicor®, was able to reduce and stabilize blood glucose levels. Researchers mention that supplementation of Allicor® could potentially prevent diabetes-related cardiovascular issues. 

A trial involving pregnant women at risk for preeclampsia found that the administration of 400mg garlic supplements was able to reduce fasting blood glucose levels. Researchers discovered this action while they were monitoring garlic’s antioxidant activity.

Summary:

Clinical research indicates that garlic may help to stabilize and reduce elevated blood sugar levels.

5. Antioxidant Properties

The benefits of garlic have been shown to reduce oxidative stress.  

A study involving postmenopausal women with osteoporosis showed that garlic supplements have the ability to significantly decrease biomarkers of oxidative stress. The women took two garlic tablets (equal to 2g of fresh garlic) daily for 1 month. 

In a trial involving pregnant women at risk for preeclampsia, 400mg garlic tablets were able to reduce oxidative stress biomarkers and stabilize metabolic processes.

In a study involving patients with essential hypertension, researchers discovered that daily supplementation of 250mg garlic for 2 months reduced oxidative stress biomarkers. In addition to the antioxidant effect, it also increased vitamin levels and total antioxidant capacity which may help protect the heart.  

Summary:

Research indicates that garlic has strong antioxidant properties. This is thought to be beneficial for overall health and wellbeing.

6. May Help With Seasonal Allergies

Garlic has also been tied been researched for its connection with helping to treat allergic rhinitis.

Allergic rhinitis, also known as hay fever, occurs when your immune system negatively responds to allergens breathed into your body. This causes causing sneezing, itchy eyes, and other unpleasant symptoms. Typical allergens include pollen, pet dander, or mold.

An animal study found that aged garlic extract helped to reduce histamine release. The researchers theorized that aged garlic extract can modify the function of mast cells, basophils, and activated T lymphocytes, all of which play a leading role in allergic cascade reactions.

A lab study discovered that garlic extract can help to reduce airway inflammation.  The researchers noted that garlic helped to reduce allergic airway inflammation levels, which included peribronchial lung eosinophils, IgG1 level in lavage and serum, mucous producing goblet cells grade, and peribronchial and perivascular inflammation. 

Another lab-based study found that garlic suppresses the body’s allergic response. The mechanism for its anti-allergic action is thought to involve suppressions of Syk, cPLA2, 5-LO, and COX-2. 

Summary:

Animal studies, along with lab research, indicate that garlic may help to reduce inflammation in the respiratory tract, which can help to reduce allergy symptoms. Human clinical studies are needed to verify these initial findings.

7. Other Benefits 

Other purported garlic health benefits include: 

May Have Hepatoprotective Effects: A recent study found that garlic may be helpful for preventing and managing liver dysfunction.

May Promote Hair Growth: Research shows that garlic may work to prevent hair loss. One randomized double-blind clinical study involved the application of a 5% odorless garlic gel in combination with a corticosteroid betamethasone valerate to the scalps of the study participants twice a day for 3 months. The group given the combination treatment experienced a greater increase in hair growth when compared to the group treated without garlic.

Summary:

Garlic has been tied to a wide variety of health benefits. Human clinical trials are needed to verify these findings.
7 garlic health benefits

Garlic Safety:

Safety Class: 1

Interaction Class:

Garlic is “generally recognized as safe” (GRAS) by the U.S. Food and Drug Administration.

The European Medicines Agency notes that garlic should be avoided up to 7 days before and after surgery due to increased bleeding risk post-operation. This may occur due to garlic’s anticoagulant activity which thins the blood. 

Garlic is known to be a blood thinner due to its anti-platelet properties. Ajoene, a compound found in garlic, inhibits platelet aggregation, which increases the effectiveness of anticoagulants such as aspirin, warfarin, dipyridamole, and clopidogrel. Consult a healthcare professional if taking any sort of anticoagulant or anti-inflammatory medication prior to ingesting a garlic supplement.

Large doses of garlic may irritate the mouth and lining of the stomach and cause a burning sensation or nausea. Overuse can also lead to a skin reaction for some individuals.

Pregnancy & Lactation:

The Botanical Safety Handbook mentions that garlic is generally safe for both pregnant and nursing mothers.

Some studies show that garlic may change the odor of breast milk and encourage increased nursing. 

There is a lack of scientific evidence around the maximum dosage one should take when pregnant. 

Dosing:

Standard dosing for garlic is as follows:

Raw Garlic: 

1 clove, 1x/day (preventative) 

1 clove, 3x/day (infection) 

Commission E recommends 4g of fresh, minced garlic daily as a preventative. 

Infusion: Add 150ml of boiling water to 4g of garlic. Let steep for 15 – 20 mins with a lid on the cup to prevent volatile oils from escaping. 

Garlic Oil: 2-5mg/day 

Fluid extract (1:1): 4 ml/day 

Tincture (1:5): 4 – 5 drops/day 

Dietary Supplement: 600-900mg/day of garlic extract (6mg allicin yield) 

1 capsule 1x/day (preventative) 

1 capsule 3x/day (infection) 

Sustainability:

Garlic is not on the United Plant Saver’s “at-risk” list and is generally considered a sustainable, safe plant.

Naming & Taxonomy:

Garlic’s scientific name is Allium sativum. It is part of the Amaryllidaceae family and is a perennial plant.

The garlic plant produces a bulb of strong-smelling cloves just below the surface of the ground. The varieties that grow in temperate climates are hardier and tend to produce more of the phytochemicals that impart the classic aroma.

The cloves have a pungent, spicy flavor and are considered the medicinal/edible section of the plant. Both fresh and dried cloves are used for culinary and medicinal purposes. 

Other common names of garlic include allium, stinking rose, poor man’s treacle, camphor of the poor, rocambole, and rustic treacle. 

There are two main subspecies of garlic; softneck and hardneck. The hardneck variety grows in temperate climates while the softneck garlic prefers tropical or subtropical regions. 

The garlic plant itself has a tall stem with narrow flat leaves that resemble grass. It loves full sunlight and well-drained, loamy soil. Plant individual cloves in September/October and harvest the bulbs in July/August. 

The garlic bulb is firm with white skin that covers the flesh of each clove. Some varieties have purple or reddish skin. Inside the skin, the cloves are a light cream/yellow color and are highly aromatic and sticky when chopped up. 

History & Traditional Use:

The medicinal and culinary use of garlic dates back thousands of years to ancient Persia, Egypt, and Greece. The first record of garlic was discovered in the Avesta collection which is Zoroastrian holy literature dating back to 6th BCE.

The garlic clove was revered and detested (for its smell) throughout ancient history, gaining fame in many Greek and Roman mythologies. From 2600–2100 BC, garlic was used therapeutically by the Sumerians. From there, garlic made its way to China and then Korea and Japan. 

There is evidence that garlic was used as a tonic in ancient times, it was given to the enslaved peoples in Egypt as a way to keep them strong.

Garlic cloves have been traditionally used for cough, hemorrhoids, skin disease, weakness, rheumatism, blood pressure, stimulating appetite, and as a parasite-killer. 

Conclusion:

Garlic is an extremely versatile medicine and food. It supports a wide range of cardiovascular issues, such as high blood pressure, infections, and diabetes. 

It also has potent antimicrobial activity.

In addition to these health benefits, garlic cloves carry the strong potential for reducing oxidative stress and inflammation, while protecting the liver. 

It is worth looking into garlic if you are experiencing any of the above complaints.

As always, make sure to consult a healthcare practitioner before making adjustments to your diet or adding a new supplement.

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About Siobhan Mendicino

Siobhan is a herbal researcher and writer. She has a bachelor of science in communications as well as having completed a post-baccalaureate certificate in herbal studies.

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