Why Does Food Taste Different When You Have a Cold?

You get a bad cold. You sit down for a meal you normally love and it tastes like nothing. Flat, grey, a vague sensation of salt and warmth without any of the specific character that makes food interesting.

You assume your taste is impaired.

Your taste is almost completely fine. What’s gone is your smell. And the reason that affects everything is that what you experience as “taste” — the complex, distinctive, recognizable quality of food — is mostly smell.

What Your Tongue Actually Detects

Your tongue is a relatively simple instrument.

The taste receptors on your tongue — organized into taste buds across the surface — can detect five basic qualities: sweet, salty, sour, bitter, and umami (the savory taste associated with glutamates in foods like meat and aged cheese). Possibly a sixth, fat, is still being studied.

That’s the whole list. Your tongue cannot distinguish between a strawberry and a raspberry. It cannot tell coffee from tea. It cannot recognize cinnamon, garlic, vanilla, or the difference between a cheap wine and an expensive one.

Those distinctions exist elsewhere.

The Route Your Nose Doesn’t Tell You About

When you’re eating, air and volatile chemical compounds move through your mouth and up through the back of your throat into your nasal cavity — a route called retronasal olfaction. The volatile molecules released as you chew reach the olfactory epithelium, a small patch of tissue high in the nasal cavity, and the olfactory receptors there generate the rich, complex signal that your brain adds to the basic taste input.

You are also smelling food through the front of your nose when you bring it to your face — orthonasal olfaction — but the retronasal route, operating continuously as you chew and swallow, is what generates the majority of flavor experience during a meal.

The olfactory system has roughly 400 types of receptors (compared to the tongue’s five) and can detect thousands of distinct molecules. The resolution is incomparably higher. What you experience as the “flavor” of almost anything is primarily the olfactory component, combined with the tongue’s basic signals and additional inputs — texture, temperature, carbonation, the mild chemical burn of spice — into a unified perceptual event.

The estimate most sensory scientists use: somewhere between 70 and 80 percent of what people call “taste” is actually smell.

What Congestion Does

When you have a cold, nasal inflammation and mucus congestion block airflow in the nasal passages. The retronasal route from the back of your throat to the olfactory epithelium is obstructed. Volatile molecules can’t reach the olfactory receptors in sufficient concentration.

The tongue is unaffected. You can still detect sweet, salty, sour, bitter, umami. But the entire olfactory dimension of flavor — the difference between one thing and another, the characteristic quality that makes food recognizable and pleasurable — is mostly gone.

What remains is the basic sensory floor. Everything tastes vaguely like the same substance at different intensities of sweet, salty, and savory.

The Test You Can Do Right Now

Close your nostrils, pinch them shut, and eat something with a distinctive flavor — a flavored jelly bean, a piece of fruit, a cracker with a spread.

You’ll get the basic taste dimensions: sweet, salty, possibly sour. But you likely won’t be able to identify what the specific food is. The strawberry jelly bean and the lemon jelly bean have similar basic sugar profiles. Without the olfactory component, the distinction disappears.

Release your nose while the food is still in your mouth.

The flavor arrives instantly. The entire characteristic quality of the food — everything that makes it that specific thing — floods in from the retronasal pathway.

This is not a trick. That route was there the whole time, dormant, waiting for air to flow.

Why You Don’t Notice It’s Your Nose

The reason this isn’t obvious is that your brain doesn’t experience it as two separate signals. The olfactory input and the taste input are integrated before they reach consciousness. You experience the output as a single unified thing called “taste” — you have no direct subjective access to which component came from where.

This is a general feature of multisensory perception. When you watch a movie and the audio and video are synchronized, you experience them as a single event, not as a picture with sound added. When you eat food and taste and smell are combined, you experience them as a single quality called flavor, not as taste with smell added.

When one component is removed — when congestion blocks the olfactory signal — the remaining perception feels impoverished, diminished, and strangely flat. But the feeling of something being missing is not a clear pointer to where the missing thing came from.

What This Means for Eating and Drinking

People who lose their sense of smell — anosmia, from infection, head injury, neurological damage, or COVID-19 — retain full taste function. They can detect sweet, salty, sour, bitter, umami. They can tell the difference between a sweet thing and a bitter thing.

What they cannot do is tell the difference between an apple and a pear, or between coffee and tea, or between a meal they used to love and one they’ve never had. The specific character of everything flattens. Many describe it as one of the more disorienting sensory losses — not because it prevents basic function, but because flavor is so embedded in the experience of food, meals, memory, comfort.

COVID-19 made this the most publicly discussed sensory loss in recent memory. Millions of people discovered, temporarily, that the flavor they’d attributed to their tongue was living in their nose the whole time.

You already knew that smell affects flavor. You didn’t know, probably, that the contribution was this large.

Almost everything that makes food worth eating is olfactory. The tongue is just the first gate.

When that gate is the only one still open, you find out what it was contributing all along: basic survival data, stripped of everything else.