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Since ancient times, garlic has been known as a miraculous ‘cure-all’, useful for everything from athlete’s foot to warding off heart disease. Its medical reputation goes back at least to 1550 BCE. During the first Olympic Games in Greece, garlic was consumed as a stimulant and in Roman times, soldiers chewed garlic before battle for strength.
Garlic belongs to the lily family and is related to onions, chives, shallots, and leeks. It is a perennial plant that is cultivated worldwide. Garlic is one of the most popular natural remedies of all time.

The research on garlic rose dramatically in 1983 when New York University Medical Center researchers showed in laboratory tests that garlic oil inhibited the development of skin cancer. In the recent years, there have been many researches done on the potential medicinal properties of garlic on health conditions, including:

  • high blood pressure
  • high cholesterol
  • heart disease
  • different types of cancer

Health benefits of garlic

There are three major types of health benefits of garlic, as confirmed by scientific studies. It helps with treating infection, protects circulation, and fights various types of toxins.

  • Treating infection

Fresh garlic has been shown to be effective against bacteria, yeasts, and fungi. It is most effective against fungi and Candida. In several studies, the ajoenes present in garlic have been successfully used to help prevent infections with the yeast Candida albicans. Also, according to research conducted at New Jersey Medical University, blood can kill fungi a half-hour after one or two cloves of fresh garlic are eaten.
Garlic is recommended for mild, recurring, or chronic infections, such as infections of the mouth, throat, stomach or skin. It can help with treatment of bronchitis, cystitis, colds, catarrh, and particularly Candida. To treat vaginitis, women can use garlic slices as a vaginal suppository, or the juice as a douche.

  • Protecting circulation

The ancient Greeks used garlic ‘to keep the arteries open’. Raw or aged garlic reliably reduces total cholesterol and Low-density Lipoprotein (LDL-C), while increasing High-density Lipoprotein (HDL-C), thus cutting the risk of heart attack. Researchers at Pennsylvania State University’s College of Health and Human Development found in laboratory tests that garlic ‘inhibited fatty acid synthesis in liver cells by up to 64 % and suppressed cholesterol synthesis by 87 %’.

Chronic inflammation could contribute to damage of our blood vessel walls, formation of plaque, and eventual clogging of our blood vessels. The vinyldithiins, diallyl polysulfoxides, and a sulfur-containing compound called thiacremonone have been most closely associated with the anti-inflammatory activity of garlic in our cardiovascular system.

Garlic protects from heart disease by preventing clots that can lead to heart attacks or strokes, and can reduce high blood pressure significantly. It can be beneficial for people with diabetes who are especially susceptible to cardiovascular diseases. Garlic can also significantly lower blood sugar levels. Timed-released garlic has been shown to reduce blood cholesterol levels, and to lower fasting blood sugar levels in patients with type 2 diabetes. Several studies have been published about the effect of garlic on lipid profile and blood glucose in diabetic patients.

  • Detoxifying

The sulfur and hydrogen compounds of garlic are potent toxic heavy metal chelators, binding and removing metals through excretions. These compounds can also protect from oxidation and free-radical damage which can lead to disease and premature aging.

Garlic aids in the detoxification of peroxides such as hydrogen peroxide and helps to prevent fats from being oxidized and deposited in tissues and arteries. Garlic also contains antioxidant nutrients such as vitamin A and C and selenium (which help with detoxification).

Aged garlic is a popular form of garlic to use for supplementation, since it does not have a fresh garlic scent. Studies on aged garlic extract (AGE) show that aging process significantly raises garlic’s antioxidant potential. AGE protects against DNA damage, keeps blood vessels healthy, and guards against radiation and sunlight damage. According to researcher and nutritionist Robert I-San Lin, Ph.D., aged garlic extract can prevent liver damage caused by carbon tetrachloride, a common indoor pollutant and free radical generator. Overall, aged garlic supplements provide a greater concentration of garlic’s beneficial compounds. It is particularly helpful to reduce oxidation associated with aging.

Garlic’s powerful compounds stimulate the immune system by increasing the potency of immune-system cells, which, in turn, help to fight microbes and cancer.

Researchers at California’s Loma Linda University found that garlic activates enzymes in the liver to destroy aflatoxin. Aflatoxin is a strong carcinogen produced by a mole found in nuts, mainly peanuts and peanut butter. The research also indicated that garlic may suppress the effects of cancer-causing agents in cigarette smoke, charbroiled meats, as well as air pollution.

A meta-analysis by the University of North Carolina of 18 studies on garlic showed that eating ten cloves of raw or cooked garlic weekly decreases the chances of colorectal cancer by 30% and stomach cancer risk by 50%.

Garlic has health-promoting properties such as:

  • Acidophilus growth stimulant
  • Antibacterial agent
  • Antioxidant and antiaging agent
  • Antiradiation treatment
  • Antistress agent
  • Antitumor agent
  • Antiviral agent
  • Heavy-metal chelation agent
  • Immune-system enchancer
  • Liver-protective agent

The following health problems may be improved by garlic consumption or supplementation:

  • Allergies
  • Arthritis
  • Asthma
  • Atherosclerosis
  • Bronchitis
  • Cancer
  • Canker sores
  • Cardiovascular disease
  • Carpal tunnel syndrome
  • Circulation
  • Colds/flu/persistent fever
  • Diabetes
  • Excessive sweating
  • Excessive unexplained weight loss
  • Fatigue
  • Fungal disease such as Candidiasis and athlete’s foot
  • Gastrointestinal disorders
  • Haemorrhoids
  • High cholesterol
  • High toxin levels
  • High triglycerides
  • Hypertension
  • Hypoglycemia
  • Impotence
  • Pneumonia
  • Sore throat
  • Swallowing difficulty
  • Swollen lymph nodes
  • Vaginal discharge
  • Varicose veins

Garlic chemistry

Garlic has a complex biochemistry. It contains various phytochemicals, including 75 different sulfur compounds. In addition, garlic is an excellent source of manganese and vitamin B6; a very good source of vitamin C and copper; and a good source of selenium, phosphorus, vitamin B1 and calcium.

The presence of the health-beneficial sulfur compounds depend upon whether the garlic is fresh or aged, raw or cooked, natural or in processed form (tablets, capsules, oils, or extracts). Garlic has a variety of bioactive compounds, including organosulfur compounds, saponins, phenolic compounds, and polysaccharides. The major active components of garlic are its organosulfur compounds, such as diallyl thiosulfonate (allicin), diallyl sulfide (DAS), diallyl disulfide (DADS), diallyl trisulfide (DATS), E/Z-ajoene, S-allyl-cysteine (SAC), and S-allyl-cysteine sulfoxide (alliin).

Crushing or slicing a garlic clove releases the enzyme alliinase. This substance in turn modifies another molecule, called alliin, into one known as allicin, which is the active component that gives garlic its aroma and flavour. Allicin benefits are especially well-researched in studies. By itself, allicin is a potent antioxidant that neutralizes cell-damaging free radicals. The garlic must be fresh, as the active ingredient is destroyed within one hour of crushing. Swallowing the clove intact will not permit the allicin to be converted into its active ingredient. Cooking, aging, and otherwise processing garlic causes allicin to break down into other compounds. During the aging process, alliin and allicin are converted to water-soluble, stable compounds that are odourless. Because allicin decomposes immediately, it is not biologically available to the body and cannot be absorbed into the bloodstream.

How to incorporate garlic in your diet and how much?

For general health promotion for adults, the World Health Organization recommends a daily dose of one of the following:

  • two to five grams of fresh garlic (could be raw, sautéed or roasted garlic)
  • 0.4 to 1.2 grams of dried garlic powder
  • two to five milligrams of garlic oil
  • 300 to 1,000 milligrams of garlic extract
  • other formulations that are equal to two to five milligrams of allicin

Note: Avoid consuming very large quantities of garlic if you take aspirin or anticoagulant drugs on a regular basis, because all three restrict clotting.

Note: In higher amounts, garlic can be irritating to the gastrointestinal tract, and when applied to the skin as raw garlic, it can cause burns.

Keep in mind that most studies have focused on the healing powers of fresh, raw, or cooked garlic, and aged garlic extract (AGE), while only a relative few have tested dried or powdered garlic supplements.

Kyolic Aged Garlic Extract from Wakunaga of America is a garlic extract that became very popular because it is standardized to contain a certain level of the two organosulfur compounds SAC and S-allylmercaptocysteine (SAMC). Unlike other aged garlic products, Kyolic contains the compound fructosyl arginine, which, in laboratory tests, proved to be as effective as vitamin C in its antioxidant activity.

Researchers at Pennsylvania State university found that both fresh garlic and aged garlic extract were effective in curbing the spontaneous formation of nitrosamines, carcinogens absorbed from food and water. A study reported in The Journal of Nutrition showed that supplementation with aged garlic extract lowered oxidative stress in humans study volunteers (both smokers and non-smokers) were given aged garlic extract once daily for fourteen days, and researchers concluded that supplementation with aged garlic may help prevent atherosclerosis and other diseases associated with oxidative stress. Aged garlic extract is odourless and tasteless for those worried about the specific garlic smell.

Other garlic supplements include garlic oil and garlic powder in capsules or tablets. Garlic oil capsules are commonly used as a therapeutic supplement. Garlic oil is good for the heart and colon, and is effective in the treatment of arthritis, candidiasis, and circulation problems. It can be used as an external or internal treatment, such as applying it to the feet or chest during colds or taking it orally as a simple means of obtaining garlic. Garlic oil is good in salad dressings, too.

You can also make our own garlic oil from chopped fresh garlic that is soaked a few days in olive oil. Experiment to find the number of cloves that gives the degree of flavour you like. Be sure to wash your hands thoroughly and rinse the garlic after peeling and before placing it in the oil. The peel may contain mold and bacteria that can contaminate the oil. Keep garlic oil refrigerated. This mixture will keep for up to a month before you need to replace it with fresh oil. If you find the odour too strong after you eat garlic, chew some springs of parsley or mint, or caraway or fennel seeds.

Some tips how to consume it:

  • Do not pulverize raw garlic in a blender. This will make it bitter.
  • To peel a garlic clove, place it on a cutting board and lay the flat side of a broad knife on top. Tap the knife sharply to split the peel, and the clove will pop out. If you need a lot of cloves, drop them in boiling water for a minute, then plunge into cold water. And the skin should slip off easily.
  • Garlic will keep for several weeks when stored in a covered container placed in a cool, dry spot – but do not refrigerate it.
  • Crush raw garlic and allow it to sit around 15 minutes before eating.
  • Whenever possible, eat it raw. The compounds that make garlic most effective, allicin and ajoene, can be destroyed by heating.
  • Don’t let garlic burn when sautéing or roasting. It turns sharp and bitter. Gently saute cloves on low heat until they become transparent.
  • To add more garlic to your diet, try mixing raw garlic with roasted red peppers and serving it as appetizer, adding raw garlic to tomato sauce, sprinkling it into a gratin, or mashing it with black beans for burritos.