Allium sativum, known as garlic

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.

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.[3] 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

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.[5]

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, and Cambodian 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 egg and olive oil produces aioli ("garlic and oil" in Provençal). 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.

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 to improve the immune system. Garlic may also protect against cancer.

However a rigorous, NIH-funded clinical trial published by the "Archives of Internal Medicine", on 26 February 2007, found that consumption of garlic, in any form, did not reduce cholesterol levels in patients with moderately high levels.

With regard to this clinical trial, Heart.org reports, "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 website says, "The findings underscore the hazards of meta-analyses made up of small, flawed studies and the value of rigorously studying popular herbal remedies". However, while garlic may not lower cholesterol levels in the bloodstream, this study does not contradict studies that show that garlic protects arteries from that cholesterol. For example, 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.

A study published in Preventive Medicine shows that garlic inhibits coronary artery calcification, a process that serves as a marker for plaque formation since the body lays down calcium in areas that have been damaged. In this year-long study, patients given aged garlic extract daily showed an average increase in their calcium score of 7.5%, while those in the placebo group had an average increase in calcium score of 22.2%.

One reason for garlic's beneficial effects may be its ability to lessen the amount of free radicals present in the bloodstream. According to a study published in Life Sciences, a daily dose of 1 ml/kg body weight of garlic extract for six months resulted in a significant reduction in oxidant (free radical) stress in the blood of patients with atherosclerosis. Since atherosclerotic plaques develop when cholesterol circulating in the bloodstream is damaged or oxidized, garlic's ability to prevent these oxidation reactions may explain some of its beneficial effects in atherosclerotic cardiovascular diseases. A German study published in Toxicology Letters indicates that garlic also greatly reduces plaque deposition and size by preventing the formation of the initial complex that develops into an atherosclerotic plaque. Called "nanoplaque," it is formed when calcium binds to proteoheparan sulfate and then to LDL cholesterol. Garlic prevents the binding of calcium to proteoheparan sulfate, thus decisively inhibiting plaque generation.

Research presented at the 6th Annual Conference on Arteriosclerosis, Thrombosis and Vascular Biology held by the American Heart Association in Washington, D.C., suggests that garlic can help prevent and potentially reverse atherosclerotic plaque formation. The laboratory studies, conducted by well-known German scientist Professor Güautnter Siegel, M.D., from the University of Medicine in Berlin, Germany, found that powdered garlic (Kwai ® garlic) reduced the formation of nanoplaque (the first building blocks of atherosclerotic plaque) by up to 40% and reduced the size of the nanoplaque that did form by up to 20%.

Laboratory research by US and Swedish scientists published in the August 2005 Proceedings of the National Academy of Sciences reveals the mechanism behind garlic's cardiovascular benefits. The compounds in garlic responsible for its pungency also excite a neuron pathway providing cardiovascular benefits. Garlic's pungency-and that of the other members of the Alliumgenus of plants, such as onions, leeks and chives-results from its organosulphur compounds, allicin and diallyl disulphide (DADS). In this current in vitro study, allicin and DADS were found to activate perivascular sensory nerve endings, inducing the relaxation and enlargement of blood vessels, lowering blood pressure and improving blood flow throughout the body.

Garlic's numerous beneficial cardiovascular effects are due to not only its sulfur compounds, but also to its vitamin C, vitamin B6, selenium and manganese:

Garlic is a very good source of vitamin C, the body's primary antioxidant defender in all aqueous (water-soluble) areas, such as the bloodstream, where it protects LDL cholesterol from oxidation. Since it is the oxidized form of LDL cholesterol that initiates damage to blood vessel walls, reducing levels of oxidizing free radicals in the bloodstream can have a profound effect on preventing cardiovascular disease.

Garlic's vitamin B6 helps prevent heart disease via another mechanism: lowering levels of homocysteine. An intermediate product of an important cellular biochemical process called the methylation cycle, homocysteine can directly damage blood vessel walls.

The selenium in garlic not only helps prevent heart disease, but also provides protection against cancer and heavy metal toxicity. A cofactor of glutathione peroxidase (one of the body's most important internally produced antioxidants), selenium also works with vitamin E in a number of vital antioxidant systems. Since vitamin E is one of the body's top defenders in all fat-soluble areas, while vitamin C protects the water-soluble areas, garlic, which contains both nutrients, does a good job of covering all the bases. Garlic is rich not only in selenium, but also in another trace mineral, manganese, which also functions as a cofactor in a number of other important antioxidant defense enzymes, for example, superoxide dismutase. Studies have found that in adults deficient in manganese, the level of HDL (the "good form" of cholesterol) is decreased.

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.

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.[23][24] 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.