Monday, February 28, 2011

Superfood: Garlic

Allium sativum, commonly known as garlic, is a species in the onion family Alliaceae. Its close relatives include the onion, shallot, leek, chive, and rakkyo. Garlic has been used throughout history for both culinary and medicinal purposes. The garlic plant's bulb is the most commonly used part of the plant. With the exception of the single clove types, the bulb is divided into numerous fleshy sections called cloves. The cloves are used for consumption (raw or cooked), or for medicinal purposes, and have a characteristic pungent, spicy flavor that mellows and sweetens considerably with cooking. The leaves, and flowers (bulbils) on the head (spathe) are also edible, and being milder in flavor than the bulbs, they are most often consumed while immature and still tender. Additionally, the immature flower stalks (scapes) of the hardneck and elephant types are sometimes marketed for uses similar to asparagus in stir-fries. The papery, protective layers of "skin" over various parts of the plant are generally discarded during preparation for most culinary uses, though in Korea immature whole heads are sometimes prepared with the tender skins intact. The root cluster attached to the basal plate of the bulb is the only part not typically considered palatable in any form. The sticky juice within the bulb cloves is used as an adhesive in mending glass and china.
The irrational fear of garlic is alliumphobia.
The ancestry of cultivated garlic is not definitely established: according to Zohary and Hopf "A difficulty in the identification of its wild progenitor is the sterility of the cultivars", though it is thought to be descendent from the species Allium longicuspis, which grows wild in central and southwestern Asia. Allium sativum grow in the wild in areas where it has become naturalised. The "wild garlic", "crow garlic", and "field garlic" of Britain are members of the species Allium ursinum, Allium vineale, and Allium oleraceum, respectively. In North America, Allium vineale (known as "wild garlic" or "crow garlic") and Allium canadense, known as "meadow garlic" or "wild garlic" and "wild onion", are common weeds in fields. One of the best-known "garlics", the so-called elephant garlic, is actually a wild leek (Allium ampeloprasum), and not a true garlic. Single clove garlic (also called Pearl garlic or Solo garlic) also exists, originating in the Yunnan province of China.
Consumer garlic can come in many formats, including fresh, frozen, dried, fermented (Black Garlic) and shelf stable products (in tubes or jars).
There are different types or subspecies of garlic, most notably hardneck garlic and softneck garlic. The latitude where the garlic is grown affects the choice of type as garlic can be day-length sensitive. Hardneck garlic is generally grown in cooler climates; softneck garlic is generally grown closer to the equator.
Garlic scapes are removed in order to focus all the garlic's energy into bulb growth. The scapes are sold separately for cooking.
Garlic is grown globally, but China is by far the largest producer of garlic, with approximately 10.5 million tonnes (23 billion pounds) annually, accounting for over 77% of world output. India (4.1%) and South Korea (2%) follow, with Russia (1.6%) in fourth place and the United States (where garlic is grown primarily as a cash crop in every state except for Alaska) in fifth place (1.4%). This leaves 16% of global garlic production in countries that each produce less than 2% of global output. Much of the garlic production in the United States is centered on Gilroy, California, which calls itself the "garlic capital of the world".
Culinary uses
Garlic is widely used around the world for its pungent flavor as a seasoning or condiment. It is a fundamental component in many or most dishes of various regions, including eastern Asia, south Asia, Southeast Asia, the Middle East, northern Africa, southern Europe, and parts of South and Central America. The flavour varies in intensity and aroma with the different cooking methods. 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 cut the top off the bulb, coat the cloves by dribbling olive oil (or other oil-based seasoning) over them, and roast them in an oven. Garlic softens and can be extracted from the cloves by squeezing the (root) end of the bulb, or individually by squeezing one end of the clove. In Korea, heads of garlic are fermented at high temperature; the resulting product, called black garlic, is sweet and syrupy, and is now being sold in the United States, United Kingdom and Australia.
Garlic may be applied to breads to create a variety of classic dishes such as garlic bread, garlic toast, bruschetta, crostini and canape.
Oils are often flavored with garlic cloves. These infused oils are used to season all categories of vegetables, meats, breads and pasta.
In some cuisine, the young bulbs are pickled for 3–6 weeks in a mixture of sugar, salt, and spices. In eastern Europe, 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 braised like asparagus. Garlic leaves are a popular vegetable in many parts of Asia. The leaves are cut, cleaned, and then stir-fried with eggs, meat, or vegetables.
Mixing garlic with egg yolks and olive oil produces aioli. Garlic, oil, and a chunky base produce skordalia. Blending garlic, almond, oil, and soaked bread produces ajoblanco.
Garlic powder has a different taste from fresh garlic. If used as a substitute for fresh garlic, 1/8 teaspoon of garlic powder is equivalent to one clove of garlic.

Medicinal use and health benefits
In test tube studies garlic has been found to have antibacterial, antiviral, and antifungal activity. However, these actions are less clear in humans. Garlic is also claimed to help prevent heart disease (including atherosclerosis, high cholesterol, and high blood pressure) and cancer. In fact, countries where garlic is consumed in higher amounts, due to traditional cuisine, have been found to have a lower prevalence of cancer. 
Animal studies, and some early investigational studies in humans, have suggested possible cardiovascular benefits of garlic. A Czech study found that garlic supplementation reduced accumulation of cholesterol on the vascular walls of animals. Another study had similar results, with garlic supplementation significantly reducing aortic plaque deposits of cholesterol-fed rabbits. Another study showed that supplementation with garlic extract inhibited vascular calcification in human patients with high blood cholesterol. The known vasodilative effect of garlic is possibly caused by catabolism of garlic-derived polysulfides to hydrogen sulfide in red blood cells, a reaction that is dependent on reduced thiols in or on the RBC membrane. Hydrogen sulfide is an endogenous cardioprotective vascular cell-signaling molecule.
Although these studies showed protective vascular changes in garlic-fed subjects, a randomized clinical trial funded by the National Institutes of Health (NIH) in the United States and published in the Archives of Internal Medicine in 2007 found that the consumption of garlic in any form did not reduce blood cholesterol levels in patients with moderately high baseline cholesterol levels.
According to the, "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."
In 2007, the BBC reported that Allium sativum may have other beneficial properties, such as preventing and fighting the common cold. This assertion has the backing of long tradition in herbal medicine, which has used garlic for hoarseness and coughs. 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 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.
Garlic cloves are used as a remedy for infections (especially chest problems), digestive disorders, and fungal infections such as thrush.
Garlic has been found to enhance thiamin absorption and therefore reduce the likelihood for developing the thiamin deficiency beriberi.
In 1924 it was found that garlic is an effective way to prevent scurvy, due to its high vitamin C content.
Garlic has been used reasonably successfully in AIDS patients to treat cryptosporidium in an uncontrolled study in China. It has also been used by at least one AIDS patient to treat toxoplasmosis, another protozoal disease.
Garlic supplementation in rats, along with a high protein diet, has been shown to boost testosterone levels.
A 2010 double-blind, parallel, randomised, placebo-controlled trial involving 50 patients whose routine clinical records in general practice documented treated but uncontrolled hypertension. Concluded that "Our trial suggests that aged garlic extract is superior to placebo in lowering systolic blood pressure similarly to current first line medications in patients with treated but uncontrolled hypertension."

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