Horseradish, a pungent condiment, is well-known for its distinctive “kick” that often leads to a burning sensation in the nose and sinuses. This feeling is common when consumed in various forms. The sensation differs from the heat of chili peppers, which typically burn the mouth, highlighting a unique interaction with the body’s sensory systems. This article explains the specific compounds and physiological responses involved.
The Chemical Culprit
The primary compound responsible for horseradish’s burning sensation is allyl isothiocyanate (AITC). AITC is not active in an intact horseradish root; it is produced when the plant’s cells are damaged, such as through grating, chewing, or cutting.
Horseradish stores precursor compounds called glucosinolates (specifically sinigrin) separately from an enzyme called myrosinase within its cells. When the plant tissue is disrupted, these two components mix. The myrosinase enzyme then acts on the sinigrin, hydrolyzing it to release AITC. AITC has a very pungent and irritating odor, and its volatility means it easily becomes airborne.
How It Triggers the Sensation
The burning sensation from AITC results from its interaction with specific receptors on nerve cells. AITC primarily activates the Transient Receptor Potential Ankyrin 1 (TRPA1) ion channels. These receptors are found on sensory nerve endings throughout the body, including those in the mouth, throat, nose, and sinuses.
When AITC binds to and activates TRPA1 channels, it causes a rapid influx of calcium ions into the nerve cells. This influx generates electrical signals transmitted along nerve pathways to the brain. The brain interprets these signals as irritation, pain, or burning, similar to how it would process actual heat or other irritants. This is a chemical irritation, not actual tissue damage, and the sensation is temporary.
Why Your Nose Feels the Burn
Horseradish primarily affects the nose and sinuses due to AITC’s properties and the distribution of sensory receptors. AITC has high volatility. When horseradish is consumed, the AITC vapors easily travel from the mouth, through the back of the throat, and up into the nasal passages and sinuses.
The mucous membranes lining the nose and sinuses are particularly rich in TRPA1 receptors and trigeminal nerve endings. The trigeminal nerve is responsible for general sensation in the face, including areas like the eyes, nose, and sinuses. This high concentration of sensitive nerve endings in the nasal cavity makes these areas highly responsive to the airborne AITC, leading to the characteristic “nose-burning” sensation. The sensation is typically fleeting, distinguishing it from the prolonged burn of capsaicin found in chili peppers.