Much of what you call a food’s flavor comes from smell.

Smell has two access routes during everyday eating. Odors can enter through the nostrils before a bite, while aromas released inside the mouth can travel toward the nose from behind during chewing and swallowing.

Olfactory sensory neurons sit in a small patch of tissue high inside the nose. Molecules stimulate their receptors, and the resulting messages allow the brain to identify odors that contribute to a food's character.

When congestion blocks aroma access, food can seem bland even though sweetness, sourness, saltiness, bitterness, and umami remain detectable. A complaint of lost taste can therefore reflect a problem with smell rather than a complete failure of taste receptors.

The National Institute on Deafness and Other Communication Disorders identifies smell and taste as chemical senses. Both depend on detecting molecules, but they use different sensory cells and routes to the brain. In smell, specialized neurons in the nasal lining detect airborne substances. These neurons connect directly to the brain, which interprets patterns of receptor activity as particular odors rather than treating every molecule as an isolated conscious sensation.

Smelling a food before eating it uses the route through the nostrils. Eating adds another route, often called retronasal smell. Chewing releases volatile molecules, and air movement carries them through the channel connecting the throat with the nose. The sensory cells receiving this information are still olfactory cells. The fact that the aroma began in the mouth does not turn it into a signal from a taste bud.

This arrangement explains a common experience during a cold or flu. If swelling or congestion prevents odor molecules from reaching the olfactory tissue effectively, a favorite food may lose much of its recognizable character. Basic taste can persist, yet identifying a flavor such as chocolate or orange becomes harder. The missing contribution is often aroma, not the ability to detect every chemical property of the food.

Flavor includes more than these two senses. Texture and temperature contribute, while other nerve endings register chemical irritation or cooling, such as the sting of an onion or the freshness of menthol. Smell also serves functions beyond eating: it can alert people to smoke, spoiled food, or certain dangerous fumes. Its contribution to meals is therefore one part of a broader sensory system with practical consequences for safety and nutrition.

Aroma can be experienced as though it belongs entirely to the mouth even when the receptors detecting it are in the nose. NIDCD's description of the throat-to-nose route resolves this apparent contradiction. The place where a volatile molecule is released and the place where it is detected are different. That distinction is essential when interpreting the everyday complaint that a cold has taken away food's taste.