The story of garlic's role in human history could fill a book, as indeed it has, many times. Its species name, sativum, means cultivated, indicating that garlic does not grow in the wild. So fond have humans been of this herb that garlic can be found almost everywhere in the world, from Polynesia to Siberia.

From Roman antiquity through World War I, garlic poultices were used to prevent wound infections. The famous microbiologist Louis Pasteur performed some of the original work showing that garlic could kill bacteria. In 1916, the British government issued a general plea for the public to supply it with garlic in order to meet wartime needs. Garlic was called Russian penicillin during World War II because, after running out of antibiotics, the Russian government turned to this ancient treatment for its soldiers.

After World War II, Sandoz Pharmaceuticals manufactured a garlic compound for intestinal spasms, and the Van Patten Company produced another for lowering blood pressure.

Garlic is widely used as an all-around treatment for preventing or slowing the progression of atherosclerosis (the cause of most heart attacks and strokes).48-50 However, there is actually relatively little in the way of meaningful evidence that it works for this purpose. The balance of the evidence suggests that garlic is not effective for treating high cholesterol,53-64,99-102,111,121; there is only minimal evidence that it offers any benefits for people withhigh blood pressure.65According to some, but not all, studies, garlic might have blood-thinning effects,15-18,112 but whether this translates into any medical benefit remains unclear.

One study found preliminary evidence that use of garlic could enhance blood sugar control in diabetes.113

Garlic has a long folkloric history as a treatment for colds and is commonly stated to strengthen the immune system. However, up until 2001, there was no supporting evidence for this use. Since then, however, evidence including a well-designed double-blindstudy does suggest that regular use of garlic extract can help prevent colds.95

In addition, folklore suggesting that garlic ingestion can ward off insect bitesmay have some truth to it, at least when garlic is taken regularly for several weeks.29

When applied topically, garlic can kill fungi,38-41 and there is preliminary evidence suggesting that ajoene, a compound derived from garlic, might help treat athlete's foot.42,43 Topical garlic can also kill bacteria on contact; however, if you take garlic by mouth, it will not work like an antibiotic throughout your system. Furthermore, oral garlic has failed to prove effective for killing Helicobacter pylori, the stomach bacteria implicated as a major cause of ulcers.46,47

Traditionally, garlic was often combined with the herb mullein in oil products designed to reduce the pain of middle ear infections ( otitis media, not external ear infections known commonly as swimmer’s ear), and two double-blind studies support this use.97,98Note: While these products may reduce pain, it is very unlikely that they have any actual effect on the infection because the eardrum prevents them from reaching the site of infection.

Preliminary evidence, including one small double-blind trial suggests that regular intake of garlic as food or as aged garlic supplements may reduce risk of various forms of cancer.30-37,114,115

Based on extremely weak evidence, garlic has been proposed as a treatment for problems related to the yeast Candida albicans, such as vaginal yeast infections,44-45oral yeast infections (thrush),110 and the purported condition discussed in some alternative medicine circles as yeast hypersensitivity syndrome.