Why Can’t You Taste Food When You Have a Cold?
Food loses some of its taste when you have a cold because you can’t smell the odor of the food. Many foods wouldn’t taste as good as they do if you couldn’t smell them. This is because smell adds to the sense of taste.
For instance, if you hold your nose, you may find it hard to tell the difference between a piece of onion and a piece of apple. But the instant you release your nose, the “taste” of the onion becomes apparent.
When you have a bad cold, and mucus blocks the nasal passages, you cannot smell food, and, thus, it seems tasteless. There are many factors that contribute to the flavor of food – the five “traditional” tastes (sweet, sour, bitter, salty, umami), smell, texture, spiciness, “coolness” (like peppermint), temperature, etc.
Smell and taste are detected in similar ways, by chemoreceptor’s expressed in taste pores by specialized cells of the lingual epithelium (tongue), and in the nose by the olfactory epithelium.
Both are affected by upper respiratory tract infections like colds and the flu, leading to diminished senses of taste and smell, and a corresponding reduction in the overall flavor of food.