Garlic

Allium sativum L., commonly known as garlic, is a species in the onion family Alliaceae. Its close relatives include the onion, shallot, and leek. Garlic has been used throughout recorded history for both culinary and medicinal purposes. It has a characteristic pungent, 'hot', flavour that mellows and sweetens considerably with cooking. A 'head' of garlic, the most commonly used plant part, comprises numerous discrete 'cloves'. The leaves and stems are sometimes eaten, particularly while immature and tender.

So-called elephant garlic is a different species (a form of leek).

Origin and distribution
The ancestry of cultivated garlic, according to Zohary and Hopf, is not definitely established: "a difficulty in the identification of its wild progenitor is the sterility of the cultivars."

Allium sativum grows in the wild in areas where it has become naturalised; it probably descended from the species Allium longicuspis, which grows wild in south-western Asia. The 'wild garlic', 'crow garlic' and 'field garlic' of Britain are the species Allium ursinum, Allium vineale and Aleum oleraceum, respectively. In North America, 'Allium vineale, known as 'wild-' or 'crow garlic', and Allium candadensis, known as 'meadow-' or 'wild garlic', are common weeds in fields.



Culinary uses


Garlic is widely used around the world for its pungent flavour, as a seasoning or condiment. Depending on the form of cooking, the flavor is either mellow or intense. It is often paired with onion, tomato, or ginger. The parchment-like skin is much like the skin of an onion, and is typically removed before using in raw or cooked form. An alternative is to coat heads of garlic and roast them in the oven. The garlic softens and can be extracted from individual cloves by squeezing one end.

Oils are often flavored with garlic cloves. Commercially prepared oils are widely available, but when preparing garlic-infused oil at home, there is a risk of botulism if the product is not stored properly. To reduce this risk, the oil should be refrigerated and used within one week. Manufacturers add chemicals and/or acids to eliminate the risk of botulism in their products.

In Chinese cuisine, the young bulbs are pickled for 3–6 weeks in a mixture of sugar, salt and spices. In Russia and the Caucasus, the shoots are pickled and eaten as an appetizer.

Immature scapes are tender and edible. They are also known as 'garlic spears', 'stems', or 'tops'. Scapes generally have a milder taste than cloves. They are often used in stir frying or prepared like asparagus. Garlic leaves are a popular vegetable in many parts of Asia, particularly Chinese, Vietnamese, Cambodian and Korean cuisines. The leaves are cut, cleaned and then stir-fried with eggs, meat, or vegetables.

Garlic is essential to several Mediterranean dishes. Mixing garlic with eggs and olive oil produces aioli ("garlic and oil" in Provençal). The Spanish variant does not use eggs. Garlic, oil, and a chunky base produce skordalia (from the Greek and Italian names of garlic). Blending garlic, almond, oil and soaked bread produces ajoblanco (ajo blanco is Spanish for "white garlic"). Le Tourin is a French garlic soup.

Storage
Domestically, garlic is stored warm (above 18°C) and dry, to keep it dormant (so that it does not sprout). It is traditionally hung; softneck varieties are often braided in strands called "plaits", or in short plaits called "grappes" Pictures.

Commercially, garlic is stored at 0°C, also dry.

Historical use
From the earliest times garlic has been used as a food. It formed part of the diet of the Israelites in Egypt (Numbers 11:5) and of the labourers employed by Khufu in constructing the pyramid. Garlic is still grown in Egypt, but the Syrian variety is the kind most esteemed now (see Rawlinson's Herodotus, 2.125).

It was consumed by the ancient Greek and Roman soldiers, sailors and rural classes (Virgil, Ecologues ii. 11), and, according to Pliny the Elder (Natural History xix. 32), by the African peasantry. Galen eulogizes it as the "rustic's theriac" (cure-all) (see F Adams's Paulus Aegineta, p. 99), and Alexander Neckam, a writer of the 12th century (see Wright's edition of his works, p. 473, 1863), recommends it as a palliative of the heat of the sun in field labor.

In his Natural History Pliny gives an exceedingly long list of scenarios in which it was considered beneficial (N.H. xx. 23). Dr. T. Sydenham valued it as an application in confluent smallpox, and, says Cullen (Mat. Med. ii. p. 174, 1789), found some dropsies cured by it alone. Early in the 20th century, it was sometimes used in the treatment of pulmonary tuberculosis or phthisis. Garlic was rare in traditional English cuisine (though it is said to have been grown in England before 1548), and has been a much more common ingredient in Mediterranean Europe. Garlic was placed by the ancient Greeks on the piles of stones at cross-roads, as a supper for Hecate (Theophrastus, Characters, The Superstitious Man); and according to Pliny, garlic and onions were invoked as deities by the Egyptians at the taking of oaths. The inhabitants of Pelusium in lower Egypt, who worshipped the onion, are said to have had an aversion to both onions and garlic as food.

To prevent the plant from running to leaf, Pliny (N.H. xix. 34) advised bending the stalk downward and covering with earth; seeding, he observes, may be prevented by twisting the stalk (by "seeding", he most likely means the development of small, less potent bulbs).

Medicinal use and health benefits
Garlic has been used as both food and medicine in many cultures for thousands of years, dating as far back as the time that the Egyptian pyramids were built. Garlic is claimed to help prevent heart disease including atherosclerosis, high cholesterol, high blood pressure, and cancer.

Animal studies, and some early investigational studies in humans, have suggested possible cardiovascular benefits of garlic. A Czech study found garlic supplementation reduced accumulation of cholesterol on vascular walls of animals. Another study had similar results, with garlic supplementation significantly reducing the placque in the aortas of cholesterol-fed rabbits. Another study showed that supplementation with garlic extract inhibited vascular calcification in human patients with high blood cholesterol.

However, a NIH-funded randomized clinical trial published in Archives of Internal Medicine in 2007 found that consumption of garlic, in any form, did not reduce cholesterol levels in patients with moderately high baseline levels.

With regard to this clinical trial, Heart.org reports:

In 2007 a BBC news story reported that Allium sativum may have beneficial properties, such as preventing and fighting the common cold. This assertion has the backing of long tradition. Traditional British herbalism used garlic for hoarseness and coughs, both as a syrup and in a salve made of garlic and lard, which was rubbed on the chest and back. The Cherokee also used it as an expectorant for coughs and croup.

Allium sativum has been found to reduce platelet aggregation and hyperlipidemia.

Garlic is also alleged to help regulate blood sugar levels. Regular and prolonged use of therapeutic amounts of aged garlic extracts lower blood homocysteine levels, and has shown to prevent some complications of diabetes mellitus. People taking insulin should not consume medicinal amounts of garlic without consulting a physician. In such applications, garlic must be fresh and uncooked, or the allicin will be lost.

Allium sativum may also possess cancer-fighting properties due to the presence of allylic sulfur compounds such as diallyl disulfide (DADs), believed to be an anticarcinogen.

In 1858, Louis Pasteur observed garlic's antibacterial activity, and it was used as an antiseptic to prevent gangrene during World War I and World War II. More recently it has been found from a clinical trial that a mouthwash containing 2.5% fresh garlic shows good antimicrobial activity, although the majority of the participants reported an unpleasant taste and halitosis.

In modern naturopathy, garlic is used as a treatment for intestinal worms and other intestinal parasites, both orally and as an anal suppository. Garlic cloves are used as a remedy for infections (especially chest problems), digestive disorders, and fungal infections such as thrush.

Garlic supplementation in rats along with a high protein diet has been shown to boost testosterone levels.

Properties
When crushed, Allium sativum yields allicin, a powerful antibiotic and anti-fungal compound (phytoncide). It also contains alliin, ajoene, enzymes, vitamin B, minerals, and flavonoids.

The percentage composition of the bulbs is given by E. Solly (Trans. Hon. Soc. Loud., new ser., iii. p. 60) as water 84.09%, organic matter 13.38%, and inorganic matter 1.53% - that of the leaves being water 87.14%, organic matter 11.27% and inorganic matter 1.59%. The phytochemicals responsible for the sharp flavor of garlic are produced when the plant's cells are damaged. When a cell is broken by chopping, chewing, or crushing, enzymes stored in cell vacuoles trigger the breakdown of several sulfur-containing compounds stored in the cell fluids. The resultant compounds are responsible for the sharp or hot taste and strong smell of garlic. Some of the compounds are unstable and continue to evolve over time. Among the members of the onion family, garlic has by far the highest concentrations of initial reaction products, making garlic much more potent than onions, shallots, or leeks. Although people have come to enjoy the taste of garlic, these compounds are believed to have evolved as a defensive mechanism, deterring animals like birds, insects, and worms from eating the plant.

A large number of sulfur compounds contribute to the smell and taste of garlic. Diallyl disulfide is believed to be an important odour component. Allicin has been found to be the compound most responsible for the spiciness of raw garlic. This chemical opens thermoTRP (transient receptor potential) channels that are responsible for the burning sense of heat in foods. The process of cooking garlic removes allicin, thus mellowing its spiciness.

When eaten in quantity, garlic may be strongly evident in the diner's sweat and breath the following day. This is because garlic's strong smelling sulfur compounds are metabolized forming allyl methyl sulfide. Allyl methyl sulfide (AMS) cannot be digested and is passed into the blood. It is carried to the lungs and the skin where it is excreted. Since digestion takes several hours, and release of AMS several hours more, the effect of eating garlic may be present for a long time.

This well-known phenomenon of "garlic breath" is alleged to be alleviated by eating fresh parsley. The herb is, therefore, included in many garlic recipes, such as Pistou and Persillade. However, since the odour results mainly from digestive processes placing compounds such as AMS in the blood, and AMS is then released through the lungs over the course of many hours, eating parsley provides only a temporary masking. One way of accelerating the release of AMS from the body is the use of a sauna. Due to its strong odor, garlic is sometimes called the "stinking rose".

Because garlic passes into the bloodstream, it can be a useful mosquito repellent. This is most likely the cause of the myth that vampires hate garlic.

Superstition and mythology
Garlic has been regarded as a force for both good and evil. A Christian myth considers that after Satan left the Garden of Eden, garlic arose in his left footprint, and onion in the right. In Europe, many cultures have used garlic for protection or white magic, perhaps owing to its reputation as a potent preventative medicine. Central European folk beliefs considered garlic a powerful ward against demons, werewolves, and vampires. To ward off vampires, garlic could be worn, hung in windows or rubbed on chimneys and keyholes.

The association of garlic to evil spirits may be based on the antibacterial, antiparasitic value of garlic, which could prevent infections that lead to delusions, and other related mental illness symptoms.

Cautions

 * Known adverse effects of garlic include halitosis (non-bacterial), indigestion, nausea, emesis and diarrhea.


 * Garlic should not be taken with warfarin, antiplatelets, saquinavir, antihypertensives, or hypoglycemic drugs.


 * Cases of botulism have been caused by consuming garlic-in-oil preparations. It is important to add acid when creating these mixtures and to keep them refrigerated to retard bacterial growth.


 * Whilst culinary quantities are considered safe during pregnancy and breastfeeding, extremely large quantities of garlic and garlic supplements have been linked with a raised risk of bleeding. Garlic may cause abortion. Some breastfeeding mothers have found their babies slow to feed and have noted a garlic odour coming from their baby when they have consumed garlic.


 * The side effects of long-term garlic supplementation, if any exist, are largely unknown and no FDA-approved study has been performed. However, garlic has been consumed for several thousand years without any adverse long-term effects, suggesting that modest quantities of garlic pose, at worst, minimal risks to normal individuals.


 * There have been several reports of serious burns resulting from garlic being applied topically for various purposes, including naturopathic uses and acne treatment. On the basis of numerous reports of such burns, including burns to children, topical use of raw garlic, as well as insertion of raw garlic into body cavities is strongly discouraged and could lead to serious injury. In particular, topical application of raw garlic to young children is extremely risky.