Garlic is a perennial plant in the family Alliaceae and genus Allium, closely related to the onion, shallot, and leek.
It grows in the wild in areas where it has become naturalised, but is thought to have originally arisen in cultivation, probably descended from the species Allium longicuspis, which grows wild in south-western Asia.
Garlic has been used throughout all of recorded history for both culinary and medicinal purposes.
The portion of the plant most often consumed is an underground storage structure called a head. A head of garlic is composed of a dozen or more discrete cloves, each of which is a botanical bulb, an underground structure comprised of thickened leaf bases. Each garlic clove may often be composed of just one leaf base, unlike onions, which almost always have multiple layers. The above-ground portions of the garlic plant are also sometimes consumed, particularly while immature and tender.
Garlic has a powerful pungent or “hot” flavor when raw, which mellows considerably when it is cooked. Raw or cooked, garlic is noted for its strong characteristic odour.
Garlic is most often used as a seasoning or a condiment. When crushed or finely chopped it yields allicin, a powerful antibiotic and anti-fungal compound (phytoncide). It also contains alliin, ajoene, enzymes, vitamin B, minerals, and flavonoids.
Garlic is widely used in many forms of cooking for its strong flavour, which is considered to enhance many other flavours. Depending on the form of cooking and the desired result, the flavour is either mellow or intense. It is often paired with onion, tomato, and/or ginger.
In culinary preparation, it is necessary to remove the parchment-like skin from individual cloves before chopping. Lightly crushing the cloves with the ball of the hand or flat of a knife makes this job much easier. A common error made by novice cooks is to misinterpret the word “clove” as meaning the entire garlic head (naturally occurring cluster of cloves, depending on the species) rather than one of its segments, thereby wildly exaggerating the amount of garlic in a recipe. Aside from the bulbs, the shoots are often pickled in Russia and states of the Caucasus and eaten as an appetizer.
Often garlic and herbs are stored in cooking oil to create an oil that is infused with the flavors of the garlic and herbs used. This is done both commercially and at home. Care must be taken when storing garlic and herbs this way at home as there is a risk of botulism developing in the oxygen-free oil if the product is not stored properly. To reduce the risk of botulism, the oil containing the garlic must be refridgerated and used within one week. Commercial producers of garlic-in-oil use a combination of salts and/or acids to eliminate the risk of botulism in their products.
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.
The well-known phenomenon of “garlic breath” is alleged to be alleviated by eating fresh parsley. This is, therefore, included in many garlic recipes, e.g. Pistou and Persillade. However, since garlic breath 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 is at best a temporary fix. One way of accelerating the release of AMS from the body is the use of a sauna. Because of its strong odour, garlic is sometimes called the “stinking rose”.
Hardneck garlic varieties feature a seedpod that grows atop a leafless stalk known as a “scape”. Immature scapes are tender and edible. They are also known as “garlic spears”, “stems”, or “tops”. Scapes generally have a milder taste than the cloves. They are often used in stir frying or prepared like asparagus.
Some scientific research indicates that garlic can have health benefits, such as preventing and fighting common cold, diminishment of platelet aggregation; a meta-analysis showing significant (8% compared to placebo) lowering of Low density lipoprotein carrying cholesterol (LDL-C); treatment of hyperlipidaemia; the significant inhibition of atherosclerosis via the use of aged garlic extract Kyolic; and the protective nature of chronic garlic intake on elastic properties of aorta in the elderly.
However more recent studies and meta-analyses have challenged the real extent to which garlic can improve cholesterol 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. It may have some cancer-fighting properties because it is high in diallyl sulphide (DADs), believed to be an anticarcinogen. Decocted garlic extracts that are left to set overnight are very effective in healing wounds. 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.
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 continue to be used by aficionados as a remedy for infections (especially chest problems), digestive disorders, and fungal infections such as thrush. They are claimed to be an effective long-term remedy for cardiovascular problems reducing excessive blood cholesterol levels, arteriosclerosis, the risk of thrombosis, and hypertension but these claims are disputed, as there has been no clinical trial that has demonstrated any such benefits. Whole cloves used as vaginal suppositories are sometimes used as a home remedy for Candidiasis (yeast infections). Garlic is also alleged to help regulate blood sugar levels, and so can be helpful in late-onset diabetes, though 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.
Garlic supplementation in rats along with a high protein diet has been shown to boost testosterone levels.
Dietary supplements in pill form, as are commonly available, claim to possess the medicinal benefits of garlic, without (in the words of one manufacturer) “the unsocial qualities associated with fresh garlic cloves”.
From the earliest times garlic has been used as an article of diet. It is very widely used in Lebanese cuisine. Many Lebanese salads contain a garlic sauce. It formed part of the food of the Israelites in Egypt (Numb. xi. 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 (cf. Virg. Ed. ii. II), and, as Pliny tells us (N.H. 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 labour.
Pliny the Elder, in his Natural History, (N.H. xx. 23) gives an exceedingly long list of scenarios in which it was considered beneficial. 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 (Nat. Hist. 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).
Garlic has been seen as a force for both good and evil. A Christian myth says that after Satan left the Garden of Eden, garlic arose in his left footprint, and onion in the right. Even in Europe, though, many cultures have turned to garlic as a protective force or white magic, perhaps because of its reputation as a powerful preventative medicine. Central European folk beliefs considered garlic a powerful ward against devils, werewolves, and vampires. To ward off vampires, garlic could be worn on one’s person, hung in windows, or rubbed on chimneys and keyholes.