Eyes watering while eating is a common, normal physiological response. This reaction often occurs when certain foods stimulate specific sensory pathways in the body. Understanding this involves exploring how our tear system functions and how food compounds interact with sensory nerves.
How Tears Form
Tears are produced by the lacrimal glands, located above the outer corner of each eye. These glands continuously secrete a fluid, mostly water and salt, which lubricates and nourishes the eye’s surface. This fluid, known as the tear film, also contains proteins, electrolytes, and other substances that protect the eye.
There are three main types of tears: basal, reflex, and emotional. Basal tears are always present, providing constant lubrication and protection. Reflex tears are produced in larger quantities as a rapid response to irritation or foreign bodies, flushing away potential threats. Emotional tears, triggered by strong feelings, have a different chemical composition, including higher levels of certain hormones and neurotransmitters. When eating causes eyes to water, it is primarily due to the production of reflex tears.
Lacrimal glands are innervated by a neural network, including branches of the trigeminal nerve (cranial nerve V), which transmits sensory information from the eye to the brain. When irritants are detected on the eye’s surface or in nearby areas like the nasal passages, these sensory nerves signal the brainstem. This activates parasympathetic nerves, leading to increased tear secretion from the lacrimal glands as a protective mechanism.
Spicy Food and Eye Watering
Spicy foods trigger eye watering due to compounds like capsaicin, found in chili peppers. When capsaicin enters the mouth or nasal passages, it interacts with specific pain receptors known as TRPV1 receptors. These receptors are present in mucous membranes and detect heat and irritants.
The activation of TRPV1 receptors by capsaicin stimulates branches of the trigeminal nerve. This stimulation sends signals to the brain, which interprets the capsaicin as an irritant. In response, the body initiates a reflex tearing response to flush away the perceived threat. This watery discharge dilutes and removes the irritating substance from sensitive tissues, including the eyes and nasal passages.
Other Foods That Make Your Eyes Water
Beyond spicy ingredients, other foods can also cause eyes to water through different chemical interactions. Onions are a well-known culprit, making eyes water when their cells are damaged during cutting. This process releases a sulfur-containing compound called syn-propanethial-S-oxide. When this volatile gas reaches the eyes, it reacts with the watery surface to form a mild sulfuric acid, stimulating sensory neurons and triggering reflex tears.
Strong aromas and vapors from pungent foods can also induce tearing. Volatile compounds from items like strong vinegars or aromatic cheeses can irritate the membranes of the nose and eyes. This irritation can activate the trigeminal nerve, leading to a reflex tearing response to clear the perceived irritant. Highly acidic foods, such as sour candies or citrus fruits, can elicit a similar reaction. The intense sourness can stimulate mucous membranes and trigger a reflex that includes eye watering, as the body attempts to dilute the acidic sensation.
When Tearing Indicates a Different Cause
While eye watering during eating is often a normal reflex, persistent or unusual tearing might suggest an underlying condition. Frey’s Syndrome, also known as gustatory lacrimation, is a rare neurological disorder where facial nerve damage causes tearing or sweating in response to eating. This occurs due to abnormal nerve regrowth, where nerves intended for salivary glands mistakenly connect to sweat or tear glands.
Paradoxically, dry eye syndrome can also lead to excessive reflex tearing. When eyes are severely dry, they become irritated, prompting lacrimal glands to produce watery tears to compensate for dryness. However, these reflex tears often lack the necessary lubricating components, perpetuating the cycle of irritation. Additionally, a blocked tear duct can cause tears to back up and spill over, which might become more noticeable during activities like eating. If tearing is persistent, painful, accompanied by other symptoms, or significantly impacts daily life, consulting a healthcare professional is advisable.