According to a study done at Yale School of Medicine, a single pain receptor is responsible for the "kick" delivered by garlic and mustard oil (also the active ingredient in mustard and wasabi).

The same sensory receptor is responsible for the response to various environmental irritants like acrolein, which accounts for the toxic and inflammatory actions of tear gas, vehicle exhaust, tobacco smoke, and the byproduct of some chemotherapy drugs widely used in the treatment of cancer, severe arthritis, multiple sclerosis, and lupus.

"We identified TRPA1 (the receptor) not only as a promising target for the development of new pain medications, but also for potential new treatments of smoking-related disease and environmental irritation," said Sven-Eric Jordt, co-author and assistant professor in the Department of Pharmacology at Yale.

The researchers examined whether neurons taken from mice lacking the TRPA1 receptor responded normally to the pungent compounds found in mustard oil and garlic. They found neurons from the TRPA1-deficient mice were completely insensitive to either ingredient. In fact, the animals lacking the sensory gene did not flinch or try to lick when mustard oil was applied to their paws. Their paws also swelled less and became less sensitive to pain in response to the mustard oil exposure.

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