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 tumor 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…
YOUR SPIT CONTAINS TESTOSTERONE
Men and women’s saliva contains hormones including testosterone, oestrogen and progesterone, cortisone and melatonin.
‘Hormones such as testosterone and oestrogen are fat-soluble, so easily pass through cells walls into the salivary glands,’ says Professor Proctor.
It’s not known what, if any, physiological function they have in saliva.
It also contains calcium, antibacterial compounds and human cells shed from the mouth lining, which is why a swab saliva test can analyse DNA.
‘Without it, you would be prone to nasty infections such as oral thrush, ulcers and gum disease,’ says Professor Proctor.