Garlic: Health Benefits, Side Effects, Uses, Dosage, Warnings?


GARLIC: Benefits, Side Effects, Uses, Dosage, Warnings?

Common name : garlic.
Scientific name : Allium sativum .
Family : Alliaceae (formerly Liliaceae or Amaryllidaceae).


Garlic provides incomparable aroma to many dishes, including salads and, of course, pasta.
The garlic bread is ten times better made with real garlic with the garlic powder.

Despite its small size, garlic is a "superfood".
It contains antioxidants help to prevent age-related diseases.
Kind or garlic capsules?

Listing our Natural Health Products section (see item garlic (pns)) deals with the use of garlic and garlic extracts in supplement form. The record here is simply that addresses garlic kind, as it is consumed raw or cooked in various food preparations.

Health Profile

Garlic has been used for hundreds of years to treat various health problems. A large number of studies have been conducted to better understand the active ingredients of garlic and their physiological effects. In these studies, garlic is used in various forms: fresh, dried, and as an extract, oil or stain. Note that this card is dedicated solely to the effects of the consumption of fresh garlic (raw or cooked) as used in various food preparations.

Active ingredients and properties
For vegetables in the family Alliaceae
Several prospective studies and epidemiology have shown that high consumption of fruits and vegetables reduces the risk of cardiovascular disease, some cancers and other chronic diseases 1.2 . Specifically, studies have shown that consumption of vegetables from the allium family (garlic, onions, shallots, chives, scallions, leeks) have a protective effect against cancers of the stomach and intestine 3.4 . To date, there are insufficient data to link with other types of cancers such as prostate, breast, esophagus and lung 4 .

For garlic
Cancer . Several epidemiological studies indicate a positive effect of garlic consumption on the prevention of certain cancers 5 . First, the results of a meta-analysis involving 18 epidemiological studies published between 1966 and 1999 shows a 30% reduction in risk of colorectal cancer and about 50% of the risk of stomach cancer when high consumption of garlic 6 . Of all the studies identified, such consumption amounted to approximately 18 g of raw garlic and cooked a week (about six cloves). Since feed intake varied widely from study to study, it is difficult to determine more precisely the minimum of garlic to consume to benefit from its effects on colorectal cancer and stomach quantity. Other studies have found an inverse relationship between garlic consumption and the incidence of cancers of the larynx 7 of the prostate 8.9 and within 10 . However, no general conclusions can be released at this time, given the low number of studies on the subject 6 .

Garlic: raw or cooked?
The enzyme found in garlic and which allows the formation of allicin and other sulfur compounds by the heat is turned off 19 . Depending on the mode and time of cooking garlic, sulfur compounds formed will be different and the amount of antioxidants may reduce 29.37 . The properties of raw garlic are well higher than those cooked garlic 19 . Trick: add garlic 20 minutes or less before the end of cooking to preserve the quality of its active compounds as possible 38 .

Garlic may slow the development of certain cancers, both in its protective action against damage from carcinogens as its ability to prevent cancer cells to grow 11 . The sulfur compounds in garlic may play an important role (see Active ingredients) 5 . Thus, garlic, on a one consuming two cloves per day (approximately 6 g of garlic), is part of a list of foods containing molecules with potential anticancer preferred in an optimal diet for prevent cancer 11 . It is important to remember that food alone can not be effective in protecting against cancer. A varied and constant consumption of several foods with a potential preventive and maintaining a healthy lifestyle are essential.

Cardiovascular disease . The American Heart Association (AHA) publishes dietary recommendations to prevent the risk of cardiovascular disease, such as high consumption of fruits and vegetables, and choice of whole grain cereals and low-fat dairy products 12 . Based on numerous research results, the AHA offers a list of specific foods that have a cardioprotective effect. Garlic is one of those foods (as well as nuts, soy, legumes and tea) and its consumption is thus added to the basic recommendations of the AHA with a view to preventing cardiovascular disease.

The majority of studies evaluating the effect of garlic on the risk factors for cardiovascular disease (such as blood pressure, cholesterol and blood glucose) were performed with supplements or garlic extracts in order to isolate the active ingredients. Overall, these studies show a tendency to slightly reduce cholesterol and blood triglycerides . Few studies have therefore evaluated the real impact of the consumption of fresh garlic (raw or cooked) on these risk factors and elsewhere they date a few years. In two of these studies, daily consumption of 3 g and 10 g of fresh garlic for respectively 16 and 8 weeks has contributed to a decrease in total cholesterol 13,14 . Further studies are needed to assess the effect of the consumption of fresh garlic on the prevention and treatment of cardiovascular disease 15 . According to the results of studies using extracts of garlic, an equivalent intake to 2 g to 5 g of raw garlic or 10 g to 15 g of cooked garlic would be needed to enjoy the benefits of certain factors risk of cardiovascular diseases such total cholesterol, LDL-cholesterol ("bad") cholesterol or high triglycerides in the blood 16 .

Infections . Garlic is used traditionally for its antimicrobial properties and for the treatment of some infections. The majority of studies on the subject have been made ​​from extracts of garlic, with often difficult to reach with a conventional dose of fresh garlic consumption. In a study in a population of a region of China, a high consumption of garlic (more than 5 kg per person per year, the equivalent of about four to five cloves of garlic a day) was weakly associated with decreased infection with the bacterium Helicobacter pylori 17 . This observation has been challenged by a clinical study in which ten people eating fresh garlic cloves a day, with no significant effect against infection H. pylori 18 . For now, the data are not sufficient to suggest that the consumption of fresh garlic bring an antimicrobial effect in the body 19 .

Beneficial active ingredients
Garlic contains many active compounds, which provide various health benefits. Several roles attributed to some of these compounds. This applies among other sulfur compounds, associated both to the prevention of cancer and cardiovascular disease. Note that the molecules phytochemicals in garlic are all active in the body and some yet to be discovered 20 . Note that the active ingredients in fresh garlic principles work synergistically to produce different effects on health.

Sulfur compounds . These substances are so named because they contain one or more sulfur atoms in their chemical structure. Sulfur compounds are released when garlic is cut, crushed or crushed 19 . At this time, alliin (an inactive and odorless garlic molecule) into contact with an enzyme and becomes allicin , which is the molecule responsible for the characteristic odor of garlic. Thereafter, the allicin is converted into other compounds such as sulfurized diallyl sulfide , the diallyl disulfide and ajoene . It is mainly these compounds that could prevent some cancer cells to multiply and protect the body against potential carcinogens 11.21 .

In some studies, allicin has been proposed as the main active compound associated with the cardioprotective effect of garlic 22 , including its ability to reduce the plaques of atherosclerosis in animals 23 . By cons, when you consider the fact that allicin is not absorbed into the blood during the consumption of garlic, it is unlikely that it contributes as such to the effect on cardiovascular health 20 . Allicin is more a transitional compound rapidly converted to other sulfur compounds which themselves are active in the body 20 . Finally, the ajoène is a compound capable of inhibiting the synthesis (formation) of cholesterol in vitro 24 and may thus play a role in the effect cholesterol attributed to garlic.

Antioxidants . Antioxidants are compounds that protect body cells from damage caused by free radicals . These are highly reactive molecules that are involved in the development of cardiovascular disease , certain cancers and other diseases associated with aging 25 . Garlic contains various antioxidant compounds such as flavonoids 26 and tocopherols 27 , in addition to sulfur compounds which also contribute to the antioxidant activity 28 . The consumption of fresh garlic (raw or cooked) increase antioxidant activity in the plasma of rats 29 , but the daily consumption of 3 g to 6 g of raw garlic for seven or eight days in humans has not confirmed this observation 30,31 . We know as well as any equivalent weight, garlic has a higher antioxidant capacity than a wide selection of vegetables 32.33 . By cons, if the frequency and size of the portion usually consumed are taken into account, the impact of garlic consumption on total antioxidant capacity remains limited compared to other vegetables consumed in larger amounts 33 .

Other compounds . The saponins are compounds found in garlic that have the ability to lower blood cholesterol in animals 34 and blood coagulation in vitro 35 , two desired effects for the prevention of cardiovascular diseases. In addition, it has been shown in animals that the garlic protein isolated may affect lipid-lowering 36 . These promising compounds could therefore be involved in the cardioprotective effect of garlic, but more studies are needed to better understand their roles.

Other properties
Garlic Is antioxidant?

We know that fresh garlic contains some antioxidants, but now its TAC index is not available.

Garlic Is acidifying?

Data not available.

Garlic he has a high glycemic load?

Data not available.

The most important nutrients
What is a "portion" of garlic?

Weight / volume

Raw garlic, 3 g / 1 clove




0.2 g


1.0 g



Dietary fiber

0.1 g

Source : Health Canada. Canadian Nutrient File , 2005.

Consumed in small quantities, garlic provides few nutrients. As against, consumed in larger quantities in a day, garlic appears to be a source of some nutrients. For example, a bulb of garlic (about 40 ml or 24 g of garlic) is a good source of manganese and vitamin B6, as well as a source of phosphorus (see our fact sheet Awards nutrient phosphorus ), iron , of copper , selenium and vitamin C.

Interactions with certain drugs
or extracts of garlic supplements interact with certain medications that thin the blood or have an anticoagulant effect. Similarly, consumption of excessive amounts of fresh garlic in taking certain anti-clotting drugs could cause an additive effect, increasing the risk of bleeding 19 . In addition, it is advisable to avoid eating garlic before surgery to reduce the risk of prolonged bleeding. Finally, in people taking drugs hypoglycemic , consumption of large amounts of fresh garlic may increase the effect of these drugs. In general, consumption of less than 4 g garlic (equivalent to one clove) per day seems prudent to avoid adverse interactions.

Side effects of garlic

Garlic can alter the taste of breast milk. The breastfeeding women should therefore monitor their consumption of garlic during this period 16 .
Eating a high and regular amount of garlic could alter blood glucose; people with diabetes should pay special attention to 16 .
Excessive consumption of raw garlic, especially when the stomach is empty, can cause gastrointestinal disorders : ingesting one to two cloves of garlic a day proves a safe dose for an adult 19 .
Garlic oil retained in
Garlic may be retained in the oil, making it possible to prolong the shelf life. By cons, it is possible that garlic contains a bacteria that causes botulism . Well preserved in oil (without oxygen) conditions are optimal for the development of toxins. Consumption of a damaged product can lead to serious food poisoning manifested by symptoms such as dizziness, blurred or double vision, difficulty in breathing, swallowing and speaking. The look, the smell and taste of an oil deteriorated will not necessarily change, so it is important to observe the following guidelines:

Always refrigerate garlic preserved in oil.
Eat immediately or within one week of the garlic oil homemade. The oils in commercial garlic should contain preservatives (acids, as vinegar or salt): check the label of the product.


Profile Section Health
Research and Writing : Caroline Trudeau, RD, nutritionist, Institute of Nutraceuticals and Functional Foods (INAF), Université Laval
Scientific review : Charles Couillard, PhD, Institute of Nutraceuticals and Functional Foods (INAF ), Laval University
Collaboration : Jasmine Coulombe, student nutrition, Laval University and Louise Corneau, RD, MSc, nutritionist, Institute of Nutraceuticals and Functional Foods (INAF), Université Laval.
(September 2006)

Garlic over time
The word " garlic "comes from Latin allium . It could be derived from a Greek word meaning "spring from" an allusion to the very fast has the bulb to split into several bulbs, which literally appear in spring. Others think it comes from the Celtic all , which means "spice".

The original center of the garlic would be a large crescent (the "growing garlic") which extends from the Caspian Sea to the west to the Tian Shan on the border of China and Kazakhstan, to the east. In this vast area, there are about 150 wild species of the genus Allium . By cons, we did not find the wild ancestor of cultivated garlic ( Allium sativum ).

The stinking rose
Shakespeare believed that garlic was not done for the noble and Cervantes recommended that people not eat onion or garlic odor to the risk that betrays an unfortunate peasant origin. "Stinking rose", "left foot footprint of Satan," the most vehement qualifiers have never failed to describe it.

The earliest writings on culture dating from the Sumerians (2500 BC. AD), but it was used before as a spice or cure. Known Egyptians, Greeks and Romans, it will spread in southern and eastern Europe. He did not know the same success in the North and in the British Isles, except occasionally as a medicinal plant in the gardens of monasteries.

Transported by sailors who still keep to protect against epidemics and the evil eye, he will win the Dominican Republic with Columbus and then disseminate throughout South America and Central America. However, it was not until XIX th century will happen in North America, under the influence of Mexican cuisine, which is very fond of. He will find fertile ground in California, particularly in the valley of Gilroy, where it will grow to a large scale and we will not hesitate to grant the status of "international capital of garlic."

Culinary uses
top To access other recipes, you can visit the site recipes, offering among others, the following recipes: recipes Garlic , Garlic Soup, Garlic Bread
How to choose
Garlic to tender stem and garlic rod hard
Garlic commonly sold in America belongs to the subspecies Allium sativum var. sativum , which is characterized by the absence of botanically a flower stalk (hence its name "garlic stem tender") and many small pods.

Myth about garlic.
Brushing teeth after eating garlic reduces bad breath.

Reality . Brushing has no effect on garlic breath, since the odor from gases released in the mouth during chewing, and in the gastrointestinal tract during digestion. These gases are at least three hours before disposal. The only way to reduce a little breath after eating is to chew parsley, mint or coffee beans.

From a culinary standpoint, subspecies Allium sativum var. ophioscorodon , which has a flower spike (hence the name "garlic hard rod" or a "garlic stick") and pod relatively fewer and larger, is much greater. It is believed that this subspecies is the older of the two and has kept some of the characteristics of wild garlic, with its flavor and, unfortunately, its short shelf life. Preserved over the centuries thanks to amateurs care, garlic stick is available today through networks of artisan producers as well as some specialty shops. In Europe, where it is known, it is not uncommon it is considered as a local product. So will he go for the pink garlic from Lautrec in France who enjoys a designation of origin.

Garlic rocambole
Such hard rod is particularly tasty, but not always easy to find.

The false garlic
so-called Quebec "elephant garlic" and in France, "headed garlic" is not garlic, but a kind of leek which is usually ready the same way, although it has neither Tang nor the virtues of garlic.

Culinary preparations
Aillet : thus called garlic grows out of the earth in the spring and that has not yet begun to form the bulb. It can be eaten with toasted in salt or lightly steamed and drizzled with vinaigrette, like leeks. It can also chop into salads, soups, etc. Search this side of Asian grocery stores.
Flower stalk : to promote the production of the bulb, the flower stalk of garlic with his bud, must be turned off shortly after its formation. Finely chopped it into all sorts of preparations, such as garlic butter . It can be found in pot in delicatessens.
Garlic cloves : roasted or broiled in its skin, garlic takes on a very special flavor that will enhance mayonnaise, salad dressings or sauces warm. The entire bulb will initially headed and brushed with oil. You can also add individual cloves in a broth or sauce and remove them before serving, or stuff a chicken to roast. At the end of cooking, you can recover the garlic and make a sauce.
Who's with me
in the view of some good eaters, the only truly effective way to avoid annoying those around him with a sulfurous breath is to convince him to eat garlic along with you ...

Ailloli : it rises like mayonnaise except that we start with crushed garlic before adding the usual ingredients. It can accompany a fish, cold meat or fondue. If we add a piece of bread soaked in fish stock and red peppers from Spain, we get a rust , traditionally served with bouillabaisse in Provence.
Aïgo-bouïdo : many soup recipes Garlic developed worldwide, is one of the simplest Aïgo-bouïdo, the mid-culinary uses, medicinal half. To prepare it, you cook six crushed cloves of garlic in a quart of boiling water for ten minutes. Then remove from heat and add sage, thyme and bay leaves and let steep a few minutes. Remove the weeds, beat an egg omelet and add to the soup while continuing to beat. Salt and pepper. This broth is served on a slice of bread mixed with oil.
Pasta : cook the garlic cloves in oil, then remove the garlic and coat the pasta with the flavored oil. Others simply prefer to add crushed garlic in hot noodles with a little melted butter or olive oil.
Bitter garlic salad : dandelion, chicory, escarole, radicchio, Treviso lose some of their bitterness and are enhanced when served with croutons income in olive oil and rubbed with garlic. Drizzle with warm dressing to soften the greens and add the bacon, if desired.
According to a lover of garlic that were clearly not lacking in humor, "a nickel under you perhaps will take the train, but garlic will guarantee you a seat."

Garlic Butter : serving frog legs, shrimp and topped with butter snails that have mixed with garlic, shallots and finely chopped parsley. Spending a few minutes in the oven at high heat. We can cook mussels in butter with garlic, herbs and white wine, covering until they open. Reduce the liquid over high heat and pour over the mussels.
Garlic bread : slice a baguette a little stale without completely split segments. Inserted between the slices of butter handled with minced garlic and salt. Lock the rod in aluminum foil, place in oven and cook over medium heat 20 to 30 minutes.
Depending on the variety, fresh garlic will keep for three to nine months. Keep it dry at room temperature, because cold and humidity have the effect of triggering the germination process.

Organic gardening
Quebec is sown garlic between 15 September and 15 October, and harvested in July of the following year. For growing in flower bed, the ideal spacing of 12 cm by 20 cm. For row crops, the plants of 15 cm, and the ranks of 20-25 cm is will space. To ensure that garlic survive the vagaries of winter, it is recommended to cover it with a thick mulch (leaves, straw or old hay). Remove the mulch in April or May to allow the earth to warm and plants off and on again to prevent weeds, against which the garlic, with narrow leaves, is defenseless.

To promote the growth of the bulb, the flower stalk of garlic varieties stick will be cut at the latest when it reaches 15 cm (around mid-June in southern Quebec). You can leave a few flower stalks grow: their deployment is a spectacle in itself and, moreover, we can harvest the bulbils that form later at the end to use as seed or food. By the way, this is for hens that love it (the bulb and bulblets), an almost surefire way to reduce the incidence of infectious diseases in poultry, including salmonellosis.

Harvesting takes place from mid-July to mid-August depending on varieties and regions, when there is five or six green leaves (the original ten) on the stem. The entire plant, with its leaves and roots, will be suspended and dry in the shade for a period of two to four weeks to complete the process of maturing and drying the bulbs. At harvest time, we absolutely must resist the urge to wash the bulbs, may block the maturation process. Once completely dry bulbs, roots and stems flush two or three inches will be cut. Set aside the pods of medium size for seed, ensuring that they are all very healthy.

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