Can we reveal our health by simply examining our tongues?

It is not uncommon for doctors and other healthcare practitioners to ask their patients to open up and say "ahhh." A close look at the tongue (and everything else inside the mouth) can reveal a lot of hidden information about the overall state of our health.

Hailed as "the strongest muscle in the body," the tongue is composed of a group of muscles that allow us to taste food, swallow and talk. Richly supplied with blood vessels and a constant flow of saliva, the tongue is constantly being cleaned, which discourages harmful bacteria forming in the mouth area.

A healthy tongue is pink and covered with small nodules called papillae. However, if we are unwell, a problem can often be detected by simply looking at our tongues for signs of anemia, cyanosis, or infections such as thrush, dehydration and kidney problems.

Now, we no longer need to be in a doctor's office to have our tongues inspected for possible illness. Karthik Ramamurthy of Rajalakshmi Engineering College in Chennai, India, and colleagues have designed a digital tongue analysis software to help people in remote areas who may not have access to a physician.

The IT specialists have trained a neural network that can take soft inputs, such as standard questions about symptoms and a digitized image of the patient's tongue, and offer a likely diagnosis, so that a healthcare professional can be contacted if necessary. The digitized images of the patient's tongue reveal discoloration, engorgement, texture and other factors that might be linked to illness.

• Smoothness and "beefiness" might reveal vitamin B12, iron or folate deficiency, and anemia.
• Black discoloration could indicate fungal overgrowth in HIV patients or prolonged antibiotic use.
• Longitudinal furrows on the tongue are associated with syphilis.
• Ulcers may indicate the presence of Crohn's disease or colitis and various other conditions.

However, the team's automated diagnostic uses the condition of the tongue in combination with other symptoms to identify whether a patient has any of various illnesses — common cold, flu, bronchitis, streptococcal throat infection, sinusitis, allergies, asthma, pulmonary edema, food poisoning and diverticulitis.

The current system allows diagnosis of 14 distinct conditions, but the team says they will be able to add eye images and use those as an additional hard input for their neural network and so extend its usefulness significantly.