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Health Benefits, Uses and Side Effects of Garlic

Health Benefits, Uses and Side Effects of Garlic


Garlic has been used as both food and medicine in many cultures for thousands of years, dating back to when the Egyptian pyramids were built. In early 18th -century France, gravediggers drank a concoction of crushed garlic in wine they believed would protect them from the plague that killed many people in Europe. More recently, during both World Wars I and II, soldiers were given garlic to prevent gangrene. Today garlic is used to help prevent heart disease, including atherosclerosis (plaque buildup in the arteries that can block the flow of blood and possibly lead to heart attack or stroke), high cholesterol, high blood pressure, and to improve the immune system. Amongst other things raw garlic is also used by some to treat the symptoms of acne, prevent cancer, reduce the risk of heart-related diseases, combat fatigue, and is even effective as a natural mosquito repellent.

Some people who want the claimed health benefits without the taste prefer to take garlic supplements. These pills and capsules have the advantage of avoiding the dreaded garlic breath.

Garlic Health Facts

Most of garlic’s properties have been backed up by modern scientific facts and research. There are two main medical ingredients which produce the garlic health benefits: allicin and diallyl sulphides.

Garlic is a sulphurous compound and in general, a stronger tasting clove that has more sulphur content and more potential medicinal value. Some people have suggested that organically grown garlic tends to have a higher sulphur level and greater benefits to health.


Garlic is rich in antioxidants, which help destroy and neutralize free radicals— particles that can damage cell membranes, interact with genetic material, and possibly contribute to the aging process as well as the development of a number of conditions, including heart disease and cancer. Free radicals occur naturally in the body, but environmental toxins (including ultraviolet light, radiation, cigarette smoke, and air pollution) can also increase the number of these damaging particles. Garlic is a powerful natural antibiotic. The bacteria in the body do not appear to evolve resistance to the garlic as they do to many modern pharmaceutical antibiotics. This means that its positive health benefits can continue over time rather than helping to breed antibiotic-resistant "superbugs".

✦ Cardiovascular disease

Studies report that garlic consumption may decrease the progression of cardiovascular disease. Cardiovascular disease is associated with several factors, including raised serum total cholesterol, raised low-density lipoprotein (LDL), and increased LDL oxidation (free radical damage), increased platelet aggregation (clumping), hypertension, and smoking. Garlic may help decrease LDL and total cholesterol levels while raising good cholesterol (high-density lipoprotein, or HDL), decreasing platelet aggregation (helps the blood flow more easily), and decreasing blood pressure. Recently, garlic was also found to decrease two other markers of cardiovascular disease, homocysteine, and C-reactive protein.

Garlic may also reduce blood pressure. Numerous studies have reported that oral garlic is associated with reduced systolic and diastolic blood pressure.

✦ Common cold

A well-designed study of nearly 150 people found that garlic helps prevent and treat the common cold. In this study, people received either garlic supplements or placebo for 12 weeks during "cold season" (between the months of November and February). Those who received garlic had significantly fewer colds than those who received placebo. Plus, when faced with a cold, the symptoms dissipated more quickly among those receiving garlic compared to those receiving placebo.

✦ Cancer Prevention

Garlic may strengthen the immune system, helping the body fight diseases such as cancer. Laboratory studies suggest that garlic may have anti-cancer activity. Studies that follow groups of people over time suggest that people who have more raw or cooked garlic in their diet are less likely to develop certain types of cancer, particularly colon and stomach cancers. In fact, a review of 7 studies researchers found a 30% reduction in risk of colorectal cancer among people who had a high intake of raw or cooked garlic. Dietary garlic may also protect against the development of breast, prostate, and laryngeal (throat) cancers.

✧ A large-scale study, called the Iowa Women's Health Study, looked at the garlic, fruit, and vegetable consumption in 41,000 middle-aged women. Results showed that women who regularly consumed garlic, fruits, and vegetables had a 35% lower risk of developing colon cancer.
✧ Garlic may help the immune system function more effectively during times of need such as in cancer. In a study of 50 patients with inoperable colorectal, liver, or pancreatic cancer, immune activity improved after they were given aged garlic extract for 6 months.
✧ Studies also suggest that aged garlic supplementation may reduce the side effects of chemotherapy, including fatigue and anorexia (lack of appetite). Further, results found that aged garlic decreased heart and intestinal damage commonly seen with certain chemotherapy agents.

While these results are promising, more research is needed to better understand whether dietary intake of garlic and other plants in the same family (such as onions, leeks, scallions, chives, and shallots) truly help protect against cancer.


Possible side effects, especially if used to excess, include garlic breath, irritation of or even damage to the digestive tract, upset stomach, bloating, body odor, a stinging sensation on the skin from handling too much fresh or dried garlic and possible allergies. Handling garlic may also cause skin lesions. Other, more rare side effects that have been reported by those taking garlic supplements include a headache, fatigue, loss of appetite, muscle aches, dizziness described as vertigo (dizziness), and allergies such as an asthmatic reaction or contact dermatitis (skin rash). Generally lauded as a health giving herb, some people do react badly to it. As with almost any food, there are a number of people who are intolerant of or actively allergic to garlic, whether through skin contact an/or ingestion.

Garlic also has blood-thinning properties. This is also important to know if you are going to have surgery or deliver a baby. Too much garlic can increase your risk for bleeding during or after those procedures.


Even if you don't have an explicit allergy to garlic, too much exposure to allicin (the compound produced when raw garlic is crushed) can cause similar symptoms. These include skin irritation, reddening and even blistering. Low level intolerance or excessive intake can result in heartburn or flatulence.

A few unfortunate people do have an actual allergy to garlic. Symptoms vary but often include stomach problems after eating garlic and a skin rash from eating or from physical contact.

Garlic allergy has also been reported to exacerbate asthma symptoms, though this is more usually related to breathing in garlic dust from dry garlic and its skins. Symptoms of garlic allergies include skin rash, temperature and headaches. Also, garlic could potentially disrupt anti-coagulants, so it's best avoided before surgery. As with any medicine, always check with your health care provider first and tell them if you are using it.

How to Take Garlic:

✦  Pediatric

An appropriate medicinal dose for children has not been established. For this reason, use of garlic for health-related reasons in children should be directed by a qualified health care provider who has experience treating children with herbal remedies.

✦  Adult

Whole garlic clove (as a food supplement): 2 - 4 grams per day of fresh, minced garlic clove (each clove is approximately 1 gram)
Aged garlic extract: 600 - 1,200 mg, daily in divided doses
Tablets of freeze-dried garlic: 200 mg, 2 tablets 3 times daily, standardized to 1.3% alliin or 0.6% allicin. Products may also be found standardized to contain 10 - 12 mg/Gm alliin and 4,000 mcg of total allicin potential (TAP).
Fluid extract (1:1 w/v): 4 mL, daily
Tincture (1:5 w/v): 20 mL, daily
Oil: 0.03 - 0.12 mL, 3 times daily

Garlic Cooking Tips and Hints

Believe it or not, one raw garlic clove, finely minced or pressed releases more flavor than a dozen cooked whole cloves.

When garlic cloves are cooked or baked whole, the flavor mellows into a sweet, almost nutty flavor that hardly resembles any form of pungency. This nutty flavor makes a surprisingly nice addition to desserts, such as brownies or even ice cream.

Cooked, whole, unpierced cloves barely have any aroma at all, while raw garlic is the strongest in flavor.

When sautéing garlic, be very careful not to burn it. The flavor turns intensely bitter, and you'll have to start over.

If you have a good garlic press, you do not need to peel garlic cloves before pressing, which can be a wonderful time-saver. Just place the unpeeled clove in the tool cavity, press and discard the skins left in the cavity.

An easy rule of thumb to remember regarding the potency of the flavor of garlic is: The smaller you cut it, the stronger the flavor. Chopping finely and/or pressing a garlic clove will expose more surfaces to the air, causing a chemical reaction to produce that strong aroma and potent flavor.

Resources: sciencedaily.com, motherearthnews.com, fyiliving.com, livestrong.com

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