The claim that rubbing a clove of garlic on the soles of your feet can make you “taste” it is a persistent piece of kitchen folklore. This phenomenon, which can take approximately 10 to 60 minutes to occur, seems to defy the basic biology of how the body senses flavor. This analysis examines the precise scientific pathways that allow compounds from the Allium sativum plant to travel from the skin to the sensory organs.
The Scientific Verdict: Absorption, Not Taste
The sensation experienced after applying garlic to the skin is not true taste, which relies on the five gustatory receptors on the tongue. Instead, the perception is olfactory, meaning it is detected by the nose. Active molecules in garlic are absorbed through the skin, enter the body’s circulation, and travel to the respiratory system. Detection occurs when they are exhaled through the breath, activating the olfactory receptors. This demonstrates that certain molecules can bypass the digestive system entirely.
Dermal Absorption and Systemic Circulation
The skin, especially the thick layer on the soles of the feet, acts as a significant barrier against foreign substances. However, the active compounds in garlic possess a chemical structure that enables them to permeate this protective layer. These molecules exhibit lipid solubility, allowing them to dissolve through the oily, lipid-based cell membranes of the skin. Once past the epidermis, the compounds reach the dermis, where they are picked up by the extensive network of capillaries. They then enter the systemic circulation and are circulated to all organs, including the lungs and the nasal passages, for eventual detection.
The Chemical Culprit: Sulfur Compounds
The molecules responsible for this sensation are volatile sulfur compounds, a signature component of garlic. When a raw clove is crushed or sliced, the enzyme alliinase reacts with the compound alliin to produce allicin. Allicin is a highly reactive, unstable compound that quickly breaks down into various smaller, volatile metabolites. These metabolites include diallyl disulfide and allyl methyl sulfide (AMS). These sulfur-containing products travel in the bloodstream and are eventually expelled from the body. Because of their gaseous nature, these compounds are released through exhalation and sweat, creating the distinctive garlic odor on the breath and skin.
The Role of Retronasal Olfaction
The final step involves a mechanism known as retronasal olfaction. When volatile sulfur compounds are carried by the bloodstream to the lungs, they are transferred into the air we exhale. As this air moves through the throat and out of the nose, the compounds pass into the nasal cavity from the back. These compounds then stimulate the olfactory receptors located high in the nose. The brain interprets these signals as a “flavor” that seems to originate in the mouth, even though the tongue’s taste buds are not involved. This explains why people report “tasting” the garlic when they are actually smelling the sulfur metabolites circulating in their breath.