What Your Tongue Can Tell You About Health

My grandmother particularly enjoyed making cold-pressed ox tongue, but it is a culinary custom I have no wish to carry on. Have you ever encountered one? As well as being enormous, it involves considerable effort: scrubbing, cooking and pressing it, then stripping away the thick skin before it can be eaten.

No thank you.

Whether from an ox or a person, tongues consist largely of muscle. Some muscles alter the tongue’s shape, while others enable it to move. Its surface is covered by specialised membranes with numerous tiny projections, known as papillae, which are connected to our taste buds. They allow us to detect the flavours and textures of what we eat.

Yet tasting food and helping us swallow are not the tongue’s only roles: how it looks may also reveal significant clues about overall health.

Technicolour tongues

The tongue can develop an unexpectedly wide variety of colours.

Consider a red tongue. When it is vividly red, swollen and inflamed, it may be called a strawberry tongue. Inflamed papillae resemble the seeds on a strawberry’s surface, and the process can start with a white coating that gives the impression of a slightly unripe strawberry. Once this layer comes away, the tongue is left strikingly red.

Although the term may sound charming, a strawberry tongue must always be treated as a serious sign. It may be a symptom of scarlet fever, caused by the bacterium streptococcus pyogenes. While highly infectious, scarlet fever can be treated with antibiotics.

If left untreated, scarlet fever may nevertheless cause complications including rheumatic fever. A strawberry tongue may also signal Kawasaki disease, a potentially severe inflammatory condition that occurs mainly in children. It too must be identified promptly and treated in hospital.

Toxic shock syndrome, an uncommon but life-threatening emergency, can also produce a strawberry tongue. It develops when bacteria from the skin enter the body and release damaging toxins. Symptoms include a high temperature, aching muscles and a characteristic "sandpaper" rash.

A strawberry tongue should therefore never be ignored.

Tongues may also become white or, perhaps surprisingly, black. Thrush, for example, can produce a white tongue, while lingua villosa nigra refers to black hairy tongue. The term describes the lengthening of the smallest papillae, causing them to resemble hairs. Smoking, a dry mouth and poor oral hygiene are associated with the condition.

Blue tongues can occur as well. Known as central cyanosis, this serious condition causes a blueish, or cyan, colour in the mouth, tongue or face because blood is insufficiently oxygenated or circulation is poor. It can arise in many heart and lung conditions, and even at high altitude. This too is a medical emergency and warrants a call to 999.

A mapped tongue

Beyond red, white, black and blue, a tongue can develop some truly unusual patterns. Geographic tongue is one such example: the rough papillae on the upper surface are replaced by areas of smooth red tissue. The resulting pattern resembles a world map, with land moving between oceans.

Remarkably, these patches may appear and disappear, continually altering the tongue’s appearance. In a sense, it resembles continental drift as the patches change position across the surface.

Geographic tongue generally causes little in the way of symptoms, though some people experience surface irritation or, at times, a burning feeling. It is completely harmless and more prevalent than might be expected, affecting an estimated 1-3% of the population.

Recognising geographic tongue can sometimes lead to the identification of other related disorders. The evidence for certain links is stronger than for others, but psoriasis, allergic conditions, asthma and diabetes have all been associated with it.

Tongue myth-busting

There are limits to what a tongue can reveal, and some purported signs still lack persuasive scientific evidence.

Take grooves or fissures on the upper tongue surface. Most people can spot one or two cracks on their own tongue, commonly including one that runs directly down the middle. This seems simply to be a normal variation.

Some individuals, however, have a greater number of deeper fissures. This is sometimes termed fissured tongue, and it appears to share certain features with geographic tongue.

Cracks have also been said to be linked to other issues, including vitamin and iron deficiencies, dry mouth, or xerostomia, and smoking, among others. Here again, the scientific evidence supporting these associations varies in strength.

One of the most persistent tongue myths is also taught in schools, which may help to perpetuate it. It is the mistaken belief that particular areas of the tongue detect particular tastes: sweetness at the tip and bitterness at the back, for instance.

This is codswallop. To begin with, nearly all papillae contain taste buds, apart from the extremely small filiform type, meaning every part of the tongue can detect every taste. In addition, these maps may leave out the fifth taste, umami. Derived from the Japanese word for delicious, umami describes savoury flavours: think Parmesan cheese, cooked meat and tomatoes.

So, although the tongue has no taste map, it may resemble a map in some people - and doctors can read it like an atlas when making a broad range of diagnoses.

Dan Baumgardt, Senior Lecturer, School of Physiology, Pharmacology and Neuroscience, University of Bristol

This article is republished from The Conversation under a Creative Commons licence. Read the original article.