When I was young, in addition to the general practitioner I usually went to see, it was not uncommon to go to see Chinese medicine. Every time I go to see a Chinese doctor, he always starts with the same three requests: Let me feel your pulse, tell me how you slept, and stick out your tongue.

Professor Lynchian, Registered Specialist Western Medicine and Registered Chinese Medicine, Western Sydney University, explained that in the practice of Chinese medicine in 2000, the tongue held a special place and was regarded as an important diagnostic tool.

"Traditional Chinese medicine believes that the tongue is a reflection of the body's organ systems and health conditions," Lynchian said. Color, wetness, shape, tongue coating, and presence of tooth marks are all taken into account in the tongue examination. For example, a pale tongue may indicate insufficient qi and blood."

In Western medicine, before the advent of pathology, doctors relied on clinical interpretations derived from examination of patients, but examining the tongue was never key.

Dr Steven Kay, deputy chair of the Royal Australian College of General Practitioners' e-health and Practice Management Expert Committee, said: "Now we are using more tests from the laboratory... The tongue is not as useful to Western medicine as it used to be." However, the body - including the skin, eyes and tongue - can indicate a variety of health states.

Of course, a rash can indicate an allergic reaction, and jaundice can indicate a liver problem. The color of the lower eyelid can be a sign of anemia, and a retinal scan can diagnose diabetes.

As for the tongue, thick white fur can indicate a fungal infection, such as thrush, Lynchian explains. A red, moss-free tongue can indicate a vitamin deficiency; And sores or lumps can be a sign of something more serious, like mouth cancer.

Yellow tongue coating indicates possible diabetes; A dry tongue indicates possible dehydration; Swelling of the tongue may indicate poor circulation or fluid imbalance; Some cancer patients may have a purple, greasy tongue. Autoimmune diseases and hormonal imbalances can also cause noticeable changes in the tongue.

The tongue reveals our health because it has a rich blood supply and is full of nerve endings.

"The tongue is connected to the heart as well as the digestive and nervous systems through various nerves and blood vessels, and changes in these systems can directly affect how the tongue looks, feels and functions," Lynchian explains.

As the first organ of the digestive tract, the tongue can also reflect the health of the gut, he added: "A healthy digestive system is often manifested as a healthy tongue, and problems such as indigestion, malabsorption or inflammation can cause changes in tongue coating, tongue color or texture."

But how accurate is the tongue as a diagnostic tool? A new paper published by researchers from Iraq's Middle Technical University and the University of South Australia looks at the progress made in computer-aided disease diagnosis based on tongue color, aiming to find out.

Using image processing to compare tongue images from 50 people with diabetes, kidney failure and anemia to a database of 9,000 tongue images, the researchers correctly diagnosed 94 percent of cases.

They also diagnosed seven other diseases with 80 percent accuracy: asthma, heart disease, cancer, infection of the lingual papilla (small bumps on the tongue that contain taste buds), tongue inflammation and flu, and COVID-19.

Lead author and adjunct associate professor Ali Abdullaila Naj said the study, combined with advances in medical diagnostics, held "great promise."

"We expect imaging systems to play a key role in advancing more effective and non-invasive diagnostic methods for the diagnosis of multiple diseases," he said.

Lynchian said the "cool thing" is that they are using advanced computer technology to do this, such as artificial intelligence. "It's a big benefit because it's less dependent on people and means fewer mistakes," he says.

As for tongue tests, more data is needed to confirm the accuracy of the method, he said. "I would certainly like to use it as an additional enhancement to clinical medicine," he says.

"Imaging can always go wrong," he said. However, if the tongue analysis shows that the patient has a condition, you will find a way to confirm it, or find a way to deny it. It allows you to focus instead of fumbling around in the dark."