Imagine that you awoke one morning to find that you had lost your senses of taste and smell. Totally. Everything you put in your mouth suddenly tasted like…well, sawdust. And everything you passed under your nose had no identifiable odour at all. Zilch!

The most obvious consequence would be the loss of one of life’s great pleasures: the infinitely varied and wonderful flavours of food. But it goes much further than that. You would also be deprived of the senses that tell us when food has gone bad, or warn us of dangerous toxins, which usually taste bitter (strychnine, for example). You would be void of sensory signals that switch on important bodily reactions. (Sweet, for instance, triggers the release of insulin.)

Such a scenario is not hypothetical. Every year, hundreds of thousands of people suffer partial or total loss of taste and smell as the result of head injuries, radiation or chemotherapy for cancer, medications, allergies, or any of a number of diseases, especially Parkinson’s and Alzheimer’s. And a great many other cases of sensory deprivation are believed to go undiagnosed.

Taste and smell are closely linked. In fact, the 10,000-odd taste buds in your tongue and soft palate (the back part of the roof of your mouth) are capable only of sensing salt, sour, sweet and bitter. All the rest of what we call taste – flavour is a better word – comes from your sense of smell. (Some scientists recognize a fifth taste category called umami, a sensation elicited by glutamate, which is found in chicken broth, meat extracts and some cheeses. Glutamate is used in the flavour enhancer MSG.)

In reality, the complexities of flavour go well beyond taste and smell. Temperature and texture (scientists call it “mouthfeel”) of food play a part, as well as something known as the “common chemical sense,” all those thousands of nerve endings – especially on the moist surfaces of the eyes, nose, mouth and throat – that pick up the sting of that onion you’re peeling, the coolness of menthol or the irritation of chili peppers.

Small wonder, then, that different things taste differently to different people. Or seem to. Despite the highly subjective nature of flavour and smell, there’s no denying that what delights me – oysters, for starters – may disgust you. Which raises some interesting questions.

For instance, can our likes and dislikes in foods be taken as signals from our body about what it needs or rejects? A case in point: animals are drawn to salt licks in the wild because they like the taste of salt. But is this craving connected to their metabolic need for salt? We humans share this craving – hence the appeal of many junk foods – but why, if our craving is rooted in bodily need, does it continue after our salt intake has reached dangerous levels?

We appear to have “taste memory” that gives us an aversion to foods that once caused us gastrointestinal problems or triggered allergic reactions. But does this work only retrospectively? Or might people with deadly allergies to some foods be warned off by an antipathy to their taste?

All children, or most of them, love sweets and would eat nothing else if given a free rein. But would they? Or would they eventually turn to other, more healthy foods in response to the urgings of their bodies? Not to mention their rotting teeth?

Unanswerable questions all, but presently the subject of much scientific research.

©Dr. Ashely Gordon, 2008.