Does Garlic Prevent Cancer?

Garlic is the edible bulb from a plant in the lily family. Garlic, onions, leeks, scallions, shallots, and chives are classified as members of the Allium genus. Thus, they are commonly described as Allium vegetables.

Does garlic prevent cancer?

A host of studies provide compelling evidence that garlic and its organic allyl sulfur components are effective inhibitors of the cancer process. These studies reveal that the benefits of garlic are not limited to a specific species, to a particular tissue, or to a specific carcinogen. Of 37 observational studies in humans using garlic and related allyl sulfur components, 28 studies showed some cancer preventive effect. The evidence is particularly strong for a link between garlic and prevention of prostate and stomach cancers. However, all of the available information comes from observational studies comparing cancer incidence in populations who consume or do not consume garlic (epidemiologic studies), animal models, or observations with cells in culture. These findings have not yet been verified by clinical trials in humans.

Can "too much" garlic be harmful?

Although health benefits of garlic are frequently reported, excessive intake can have harmful effects. Studies have reported symptoms including garlic odor on breath and skin, occasional allergic reactions, stomach disorders and diarrhea, decrease in serum protein and calcium levels, association with bronchial asthma and contact dermatitis, and possible associations with production of sperm in males. Garlic preparations vary in concentration and in the number of active compounds they contain. Thus, quality control is an important consideration when foods such as garlic are considered for use as a cancer-fighting agent.