[4][5] It has long been used as a seasoning and culinary ingredient worldwide, with a history of several thousand years of human consumption and use, including use in traditional medicine.

[14] Although many humans enjoy the taste of garlic, these compounds are believed to have evolved as a defensive mechanism, deterring animals such as birds, insects, and worms from eating the plant.

[citation needed][a] Genetically and morphologically, garlic is most similar to the wild species Allium longicuspis, which grows in central and southwestern Asia.

[3] The California Department of Food and Agriculture conducts a certification program to assure freedom from nematode and white rot disease caused by Stromatinia cepivora, two pathogens that can both destroy a crop and remain in the soil indefinitely once introduced.

According to the University of California,Initial symptoms usually begin at the neck, where affected tissue softens, becomes water-soaked, and turns brown.

Garlic does well in loose, dry, well-drained soils in sunny locations, and is hardy throughout USDA climate zones 4–9.

Studies have shown sipping milk at the same time as consuming garlic can significantly neutralize bad breath.

[38] Upon cutting, similar to a color change in onion caused by reactions of amino acids with sulfur compounds,[39] garlic can turn green.

[2] Symptoms can include irritable bowel, diarrhea, mouth and throat ulcerations, nausea, breathing difficulties, and, in rare cases, anaphylaxis.

[10] Garlic-sensitive people show positive tests to diallyl disulfide, allylpropyldisulfide, allylmercaptan, and allicin, all of which are present in garlic.

People who suffer from garlic allergies are often sensitive to many other plants, including onions, chives, leeks, shallots, garden lilies, ginger, and bananas.

[10] Possible side effects include gastrointestinal discomfort, sweating, dizziness, allergic reactions, bleeding, and menstrual irregularities.

[10][46] Garlic may interact with warfarin,[10] saquinavir, antihypertensives, calcium channel blockers, the quinolone family of antibiotics such as ciprofloxacin, and hypoglycemic drugs, as well as other medications.

[47] Because of sulfur compounds circulating in blood, consumed garlic may act as a mosquito repellent, although there is no scientific evidence of its efficacy.

Per 100 gram serving, raw garlic is a moderate source (10–19% DV) of the B vitamins, thiamin and pantothenic acid, as well as the dietary minerals, calcium, potassium, phosphorus, and zinc.

[51] The distinctive aroma is mainly due to organosulfur compounds including allicin present in fresh garlic cloves and ajoene which forms when they are crushed or chopped.

Green garlic is often chopped and stir-fried or cooked in soup or hot pot in Southeast Asian (i.e. Vietnamese, Thai, Myanmar, Lao, Cambodian, Singaporean), and Chinese cookery, and is very abundant and low-priced.

[19] Inedible or rarely eaten parts of the garlic plant include the "skin" covering each clove and root cluster.

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.

Tuong ot toi Viet Nam (Vietnam chili garlic sauce) is a highly popular condiment and dip across North America and Asia.

Garlic was placed by the ancient Greeks on the piles of stones at crossroads, as a supper for Hecate (Theophrastus, Characters, The Superstitious Man).

[68] Infection may first appear as soft or water-soaked spots, followed by white patches (of mycelium) which turn blue or green with sporulation.

[69] As sporulation and germination are delayed at low temperature, and at −4 °C are inhibited entirely,[70] in refrigerated cloves one may only see the white mycelium during early stages.

As of 2016, clinical research found that consuming garlic produces only a small reduction in blood pressure (4 mmHg),[73][74][75][76] and there is no clear long-term effect on hypertension, cardiovascular morbidity or mortality.

[80][81] A 2016 meta-analysis of case-control and cohort studies found a moderate inverse association between garlic intake and some cancers of the upper digestive tract.

Galen, writing in the second century, eulogized garlic as the "rustic's theriac" (cure-all) (see F. Adams' Paulus Aegineta, p. 99).

Alexander Neckam, a writer of the 12th century (see Wright's edition of his works, p. 473, 1863), discussed it as a palliative for the heat of the sun in field labor.

In the 17th century, Thomas Sydenham valued it as an application in confluent smallpox, and William Cullen's Materia Medica of 1789 found some dropsies cured by it alone.

[3] An environmentally benign garlic-derived polysulfide product is approved for use in the European Union (under Annex 1 of 91/414) and the UK as a nematicide and insecticide, including for use in the control of cabbage root fly and red mite in poultry.

[90][91] Some Mahāyāna Buddhists and sects in China and Vietnam avoid eating onions, garlic, scallions, chives and leeks, which are known as Wu hun ((Chinese: 五葷; pinyin: Wǔ hūn), 'the five forbidden pungent vegetables').