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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.

Vernacular names

• Garlic (English)
• Aglio (Italian)
• Ail (French)
• Alho (Portuguese)
• Kitunguu saumu, somu, thumu (Swahili)
• Poondu (பூண்டு) in Tamil
• Ajo in Spanish
• Hvitløk (Norwegian)
• Hvidløg (Danish)
• Knoblauch (German)
• Cesnak (Slovakian)
• Knoflook (Dutch)
• Rowshoon (Bengali)

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." It is believed to originate from Central Asia (Kazakhstan, Uzbekistan, and western China). This was confirmed by phylogenetic analysis based on molecular and biochemical markers, also indicating a secondary diversity centre in the Caucasus. Garlic spread to the Mediterranean in ancient times. It was already grown in Egypt in 1600 BC and is an ancient crop in India and China as well. At present garlic is grown all over the world from the equator to latitudes of 50° in both hemispheres, but is most popular in China, the Mediterranean and Latin America. In tropical Africa, garlic is grown during the cold season in the Sahel and at high elevations in East and southern Africa. It is a popular crop in the savanna zone, with a wide genetic variation in local cultivars. It is rarely, if ever, found in hot and humid lowlands.

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 southwestern 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 "wild" or "meadow" garlic, are common weeds in fields.

Uses around the world

After onion, garlic is the second most widely used cultivated Allium. The bulbs, composed of bulblets tightly packed around the previous season's stalk, whose easily divisable character has led to their being called "cloves", are mainly used for flavouring meat, fish, sauces and salads, raw or cooked, or, more recently, in dehydrated form. Apart from bulbs, the young floral stems are also used in Spain, China and Indonesia, and whole young green plants are used as well.

Garlic is much valued as a phyto-therapeutic crop. Garlic users, including many African people, extol its taste and health qualities. Crushed raw garlic is strongly antibiotic and has a reputation for lowering blood pressure and inhibiting thrombus formation, though its reputation in urban mythology for lowering cholesterol has been disproven.. Leaves and bulbs are considered to have hypotensive, carminative, antiseptic, anthelmintic, diaphoretic and expectorant properties. Several attributed prophylactic qualities are questionable, but have resulted in a rich supply of and demand for medicinal pills, drinks and powders based on garlic extracts.

Culinary uses

Garlic is widely used around the world for its pungent flavour, as a seasoning or condiment or to enhance 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. It is widely used in Lebanese cuisine: many Lebanese salads contain a garlic sauce.

It is necessary to remove the parchment-like skin from the cloves before cooking. The term 'clove' is sometimes misinterpreted to mean the whole garlic bulb (head).

Garlic is commonly stored in cooking oil with herbs to yield an oil infused with flavour. Garlic-infused oils are widely available. Care must be taken preparing these, 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 refrigerated and used within one week. (see Caution below). Commercial producers use a combination of salts 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. Pickled garlic is available at supermarkets. The shoots are often pickled in Russia and states of the Caucasus 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 in particular Chinese, Vietnamese, and Cambodian. The leaves are cut, cleaned and then stir-fried with eggs, meat or vegetables.

Historical use

Garlic formed part of the food 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

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A report published in the Archives of Internal Medicine (AIM) on 26 February 2007 found that consumption of garlic, in any form, did not reduce cholesterol levels in patients with moderately high levels . Inexplicably, this trial was referred to by one Misplaced Pages editor as "definitive"; whereas, there have been dozens of clinical trials on garlic in hyperlipidemias, some of them of comparable quality, and most of them coming to the opposite conclusion. (What it was that made this trial "definitive" was not disclosed.) These trials, up to the year 2000, were carefully reviewed by the Agency for Healthcare Research and Quality (AHRQ; U.S. Department of Health and Human Services), which noted that "thirty-seven randomized trials, all but one in adults, consistently showed that compared with placebo, various garlic preparations led to small, statistically significant reductions in total cholesterol at 1 month" The AHRQ report went on to state that the clearly beneficial effect of garlic is typically not sustained beyond 3 months, with most trials indicating no effect at 6 months. This suggests that the benefit of garlic may be better obtained with a cycling schedule than with continuous administration.

Other trials have been published since the AHRQ report, and indeed since the AIM article cited above. Notably, a single-blind, placebo-controlled study of garlic supplements in 150 hyperlipidemic subjects was published just days after the AIM publication. This trial (Kojuri et al) found highly-significant reductions of total cholesterol and LDL cholesterol, along with a surprisingly robust increase of HDL cholesterol ("good" cholesterol), after 6 weeks of treatment. Here again, as per the AHRQ report, it is not known whether this effect would persist at longer trial lengths, and it seems likely that it would not, if administration were continuous.

After the AIM publication, TheHeart.Org anounced that "Despite decades of research suggesting that garlic can improve cholesterol profiles, a new NIH-funded trial found absolutely no effects of raw garlic or garlic supplements on LDL, HDL, or triglycerides. The findings underscore the hazards of meta-analyses made up of small, flawed studies and the value of rigorously studying popular herbal remedies" . Oddly, TheHeart.Org seems intent on denouncing garlic, since the phrases "absolutely no effects" and simply "no effects" convey the same objective meaning, while the word absolutely performs no work except to excite emotions. Further, TheHeart.Org seems not to have paid much direct attention to the literature on the subject, which includes its share of well-designed, blinded and controlled trials (see, e.g., the Kojuri study cited above) in addition to small, flawed studies. The AHRQ report, mentioned above, is a good portal to the literature.

Fortunately, both the AHRQ report and the Kojuri study, cited above, are available publicly in full text at the links, whereas the AIM study, the accompanying editorial, and the TheHeart.Org commentary are all restricted to paying subscribers.

A BBC news story reported that Allium sativum may have beneficial properties, such as preventing and fighting the common cold.

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

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 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 are used as a remedy for infections (especially chest problems), digestive disorders, and fungal infections such as thrush. Whole cloves used as vaginal suppositories are sometimes used as a home remedy for Candidiasis (yeast infections).

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".

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".

Superstition and mythology

Garlic has 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.

Cultivation

Allium sativum is cultivated in the same manner as the shallot. The domesticated garlic plant does not produce seeds, but is grown from bulbs. These bulbs are the part of the plant most commonly eaten.

A bulb or head of garlic is white to pinkish purple, and usually measures 4-8cm in diameter. The bulb comprises numerous 8 - 25) discrete cloves. A central scape (25-100cm) supports flat or keeled (but not tubular) leaves, 30-60cm long x 2-3cm broad. Flowers are borne on a spherical inflorescence and are white, pink or purple, with six tepals 3 - 5 millimetres long. The flowers are commonly abortive and rarely produce any seeds. Bulbils may also be borne on the umbel, which is initially surrounded by a papery basal spathe splitting on one side.

Numerous cultivars are available, and are broadly classified as 'hardneck' and 'softneck' types. Hardneck types possess more intense flavours but less longevity in storage, and are closely related to their wild relatives. In contrast, softneck types have a long shelf life but less pungent flavour. If of fair size, four to six bulbs together weigh about 500 g (1 lb).

Storage

Varieties of Allium sativum differ not only in flavour, but in the storage potential of the bulbs. The bulbs are best preserved hanging in a dry place, away from direct sunlight. Under good storage conditions (room temperature and medium to low humidity), the following storage periods may be achieved:

• Asiatic, Turban and Porcelain types: a few months
• Rocambole and Purple Stripe types: 6 to 8 months (but have a tendency to dehydrate in less than 50% humidity)
• Artichoke types: 8 to 10 months
• Silverskin (including Creole) types: up to a full year

Cautions

• 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. 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.

Trivia

• The city of Gilroy, California promotes itself as "Garlic Capital of the World", and hosts the three-day Gilroy Garlic Festival every summer.

• The two-day Hudson Valley Garlic Festival is held yearly in Saugerties, New York.

• In the televised cartoon shorts, before he used spinach as a source of superhuman strength, comic book character Popeye's ancestor Hercules would sniff fresh bulbs of unpeeled garlic.

References

Notes

1. Gernot Katzer's Spice Pages.
2. ^ Grubben, G.J.H. & Denton, O.A. (2004) Plant Resources of Tropical Africa 2. Vegetables. PROTA Foundation, Wageningen; Backhuys, Leiden; CTA, Wageningen.
3. ^ PROTAbase on Allium sativum
4. Daniel Zohary and Maria Hopf, Domestication of plants in the Old World, third edition (Oxford: University Press, 2000), p. 197
5. Saulnkhe and Kadam p. 397
6. McGee p. 112
7. A study conducted at Stanford University by Christopher Gardner and published in Archives of Internal Medicine "Garlic Does Not Lower Cholesterol".
8. http://www.hc-sc.gc.ca/iyh-vsv/food-aliment/garlic-ail_e.html
9. Balch, Phyllis A. (2000). Prescription for Nutritional Healing, 3rd ed. New York: Avery. p. 97.
10. Garlic - What We Know and What We Don't Know Retrieved 27 Feb 2007
11. Effect of Raw Garlic vs Commercial Garlic Supplements on Plasma Lipid Concentrations in Adults With Moderate Hypercholesterolemia - A Randomized Clinical Trial Retrieved 26 Feb 2007
12. AHRQ Evidence Reports: 20. Garlic: Effects on Cardiovascular Risks and Disease, Protective Effects Against Cancer, and Clinical Adverse Effects Retrieved 14 March 2007
13. Kojuri et al: Effects of anethum graveolens and garlic on lipid profile in hyperlipidemic patients. Lipids in Health and Disease 2007, 6:5 doi:10.1186/1476-511X-6-5 Retrieved 14 March 2007
14. Goodbye, garlic? Randomized controlled trial of raw garlic and supplements finds no effect on lipids Retrieved 27 Feb 2007
15. Garlic 'prevents common cold' 2007
16. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2291748&dopt=Abstract
17. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9641475&dopt=Citation
18. People with diabetes should say 'yes' to garlic by Patricia Andersen-Parrado, Better Nutrition, Sept 1996
19. Garlic - University of Maryland Medical Center
20. Abstract
21. Health effects of garlic American Family Physician by Ellen Tattelman, July 1, 2005
23. McGee p. 310-311
24. Macpherson et al. section "Conclusion"
25. Macpherson et al.
26. Pickering, David (2003). Cassell's Dictionary of Superstitions. Sterling Publishing. ISBN 0-304-36561-0. p. 211
27. ^ McNally, Raymond T (1994). In Search of Dracula. Houghton Mifflin. ISBN 0-395-65783-0. p. 120. Cite error: The named reference "asdf" was defined multiple times with different content (see the help page).
28. McNalley p. 122; Pickering p. 211.
29. http://www.colostate.edu/Orgs/safefood/NEWSLTR/v2n4s08.html
30. Mayo Clinic, garlic advisory
31. Abstract

Bibliography

• McGee, Harold (2004). On Food and Cooking (Revised Edition). Scribner. ISBN 0-684-80001-2. pp 310–313: The Onion Family: Onions, Garlic, Leeks.
• Salunkhe, D.K.; Kadam, S.S. (1998). Handbook of Vegetable Science and Technology. Marcel Dekker. ISBN 0-8247-0105-4.{{cite book}}: CS1 maint: multiple names: authors list (link)
• Koch, H. P.; Lawson, L. D. (1996). Garlic. The Science and Therapeutic Application of Allium sativum L. and Related Species (Second Edition). Williams & Wilkens. ISBN 0-683-18147-5.{{cite book}}: CS1 maint: multiple names: authors list (link)
• James Mellgren (2003).
• Hamilton, Andy (2004). Selfsufficientish - Garlic. Retrieved 1 May 2005.
• R. Kamenetsky, I. L. Shafir, H. Zemah, A. Barzilay, and H. D. Rabinowitch (2004). Environmental Control of Garlic Growth and Florogenesis. J. Am. Soc. Hort. Sci. 129: 144-151.
• Lindsey J. Macpherson, Bernhard H. Geierstanger, Veena Viswanath, Michael Bandell, Samer R. Eid, SunWook Hwang, and Ardem Patapoutian (2005). "The pungency of garlic: Activation of TRPA1 and TRPV1 in response to allicin". Current Biology. 15 (May 24): 929–934. {{cite journal}}: External link in |title= (help)CS1 maint: multiple names: authors list (link)
• Balch, P. A. (2000). Prescription for Nutritional Healing, 3rd ed. New York: Avery.
• Block, E. (1985). The chemistry of garlic and onions. Scientific American 252 (March): 114-119.
• Block, E. (1992). The organosulfur chemistry of the genus Allium — implications for organic sulfur chemistry. Angewandte Chemie International Edition 104: 1158-1203.
• Breithaupt-Grogler, K., et al. (1997). Protective effect of chronic garlic intake on elastic properties of aorta in the elderly. Circulation 96: 2649-2655. Abstract.
• Efendy, J. L., et al. (1997). The effect of the aged garlic extract, 'Kyolic', on the development of experimental atherosclerosis. Arterosclerosis 132: 37-42. Abstract.
• Hile, A. G.; Shan, Z.; Zhang, S.-Z.; Block, E. (2004). Aversion of European starlings (Sturnus vulgaris) to garlic oil treated granules: garlic oil as an avian repellent. Garlic oil analysis by nuclear magnetic resonance spectroscopy. Journal of Agricultural and Food Chemistry 52: 2192-2196.
• Jain, A. K. (1993). Can garlic reduce levels of serum lipids? A controlled clinical study. American Journal of Medicine 94: 632-635. Abstract.
• Lawson, L. D.; Wang, Z. J. (2001). Low allicin release from garlic supplements: a major problem due to sensitivities of alliinase activity.Journal of Agricultural and Food Chemistry 49: 2592-2599.
• Mader, F. H. (1990). Treatment of hyperlipidemia with garlic-powder tablets. Arzneimittel-Forschung/Drug Research 40 (2): 3-8. Abstract.
• Silagy, C., and Neil, A. (1994). Garlic as a lipid-lowering agent - a meta-analysis. Journal of the Royal College of Physicians 28 (1): 2-8. Abstract
• Steiner, M., and Lin, R.S. (1998). Changes in platelet function and susceptibility of lipoproteins to oxidation associated with administration of aged garlic extract. Journal of Cardiovascular Pharmacology 31: 904-908. Abstract
• Yeh, Y-Y., et al. (1999). Garlic extract reduces plasma concentration of homocysteine in rats rendered folic acid deficient. FASEB Journal 13(4): Abstract 209.12.
• Yeh, Y-Y., et al. (1997). Garlic reduced plasma cholesterol in hypercholesterolemic men maintaining habitual diets. In: Ohigashi, H., et al. (eds). Food Factors for Cancer Prevention. Tokyo: Springer-Verlag. Abstract. This is a meta-reference and includes 205 scientific and non-scientific papers from the United States National Library of Medicine .

External links

• Plant Resources of Tropical Africa
• PROTAbase
• Garlic: Plants For a Future database

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