by Dr John Winsor - The Sunday Times of Malta

Taste enables us to differentiate between bitter, sweet, salty or sour flavours. Smell is also used to help distinguish between tastes, so disturbance of smell can alter our taste appreciation. For instance, if your nose is blocked due to a cold, you can’t smell and appear to lose your sense of taste as well.

Dysgeusia is the medical word for disturbance of taste sensation, and it usually occurs when we have a dry mouth.

Each person has about 10,000 tastebuds. Most are on the tongue but there are also a few on the back of the throat. They are contained in raised pimples, or papillae. Large papillae are mushroom-shaped and called fungiform. The smaller ones are filliform papillae and look like mountain peaks when seen under the microscope.

If you poke your tongue out and have a look at the surface in a mirror, you can see small and large papillae on the rough-textured surface. Taste pores — long-necked tubes — in these pimples are surrounded by four types of taste buds, each of which is composed of special cells which are sensitive to either sweet, sour, salty or bitter flavours.

Certain chemicals in food and drink provoke these tastes by dissolving in saliva and entering the pore. Hairs projecting from these cells into the pore are stimulated by the chemicals. When a nerve is provoked in this way, it sends messages to the brain via the glossopharyngeal nerve, helping us perceive taste.

However, if we have a dry mouth, there is not enough saliva to dissolve all the chemicals and appreciate the full flavour.

Complete or partial loss of taste usually stems from degeneration of the taste buds due to the aging process. But the most common cause is a dry mouth, which can be caused by many factors, including some drugs.

Smoking also dries the mouth. The nicotine paralyses the hairs in the cells and adds a taste of its own, so smokers cannot appreciate to the full the delicacy of the food they are eating. Another common cause of taste loss is blocking by other strong food chemicals. For instance, spices and garlic overpower the taste buds and produce a distorted sensation of flavours.

Damage to taste buds also arises from inflammation — stomatitis — or nasty conditions such as cancer of the mouth, or where radiotherapy has been given.

The special nerves conveying the taste messages can be damaged in a head injury, tumour of the brain or after surgery on the head and neck. Some psychiatric illnesses cause disturbances of taste, probably because of hallucinations rather than true taste loss.

So, when you realise you’ve had a really tasty meal, you’ve got a lot to be thankful for!