Astonishing things your saliva reveals about you - Facts n Figs - Facts About Food, Health, Fitness & Beauty


Astonishing things your saliva reveals about you

  • 'It might be 99 per cent water, but it is far more than that'
  • Saliva carries substances that fight germs and promote wound healing
Your saliva is possibly not something you have given much thought to - but it plays a vital role in maintaining good health, says Gordon Proctor, a professor in salivary biology at King's College, London.
'Saliva is a remarkable substance. It might be 99 per cent water, but it is far more than that,' he says.
In fact, saliva carries the same bacteria found in your gut, as well as powerful substances that fight germs and promote wound healing - which might be why we instinctively pop our finger in our mouth if we cut or graze it.

Now, it is being used to detect serious disease. The University of California, Los Angeles recently announced that it had developed a £15 saliva test to spot early-stage lung cancer before it can be detected with a blood test.

The test looks for fragments of tumour DNA in a single drop of saliva, and can give a result in less than ten minutes.

Saliva is already used to see if someone has had an infection such as human papilloma virus (linked to cervical cancer), and scientists are developing ways of using it to monitor such conditions as diabetes, which would be cheaper and easier than urine or blood tests.

Here, we look at the sometimes surprising significance of saliva...



Saliva is produced by the salivary glands. There are three pairs of them: in the cheeks (the parotid glands), the jaw (submandibular) and under the tongue (sublingual), which send saliva through ducts into the mouth. Each produces a slightly different formula.

'The parotid glands produce watery saliva, which helps moisten food when you chew,' says Professor Proctor.

Without saliva, you would be prone to nasty infections such as oral thrush, ulcers and gum disease
Saliva from under the tongue is much stickier and is the special 'protective layer' that coats the inside of the mouth when you are not eating.

We produce less saliva at night because we're effectively fasting, so there's no chewing action to stimulate the flow -that's why we can wake up wanting water.

When we see and smell food, the brain signals the salivary glands to produce more saliva. 'Even more is produced when we start chewing,' says Professor Proctor.
This is because mechanoreceptors (sense cells that register touch or sound) in the lining of the mouth and in the gums register the pressure of chewing and pass signals to the brain.


Saliva is also vital in helping to prevent tooth decay and erosion. 'Saliva contains a buffer that neutralises acidity,' explains Dr Mervyn Druian, a London-based dentist.

There are also potent antibacterial compounds in saliva, which help to eliminate plaque-causing bacteria.


The average person produces between 1 and 2 litres of saliva each day, around the same as your urine output.

Lack of saliva may be a sign of a health problem.


A study published last December in the journal PLOS One, a peer-reviewed scientific journal published by the Public Library of Science, found that levels of a particular antibody found in saliva falls as death approaches.

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