Oct 212011

Saliva is a cocktail of natural chemicals

The average healthy person secretes half a litre (500 mls) of saliva a day into their mouth from six glands. When we are at rest the rate of saliva production falls to around 0.3 ml per minute but when we start chewing something it then rises to 5 ml per minute . As we continue to chew it slowly falls and after about 20 minutes it will be around half this rate.

Of course the vast majority of saliva is water (99.5% in fact). However, the other 0.5% is a mixture of soluble chemicals which play a key role in providing enzymes to help us digest our food. And not only does saliva do this, it also keeps our mouth and teeth in good condition.

The chemicals in saliva are various organic molecules, inorganic ions, and large organic molecules including proteins.

The organic molecules are urea, amino acids, fatty acids, uric acid, lactate and glucose and they come from the body’s plasma so they vary according to amounts in that fluid.

The inorganic ions are chloride (Cl-), potassium (K+), sodium (Na+), phosphate PO43-), bicarbonate (HCO3-), calcium (Ca2+), and magnesium (Mg2+). The calcium and phosphate are needed to keeping the teeth in good condition because tooth enamel is a type of calcium phosphate, and saliva can help repair the teeth. The pH of saliva is 7, in other words it is neutral, and this helps to promote re-mineralisation of the tooth enamel. It is only when the pH falls below 5.5 that slight demineralisation occurs.

The large molecules in saliva are proteins, glycoproteins, antibodies, lipids and enzymes. The last of these are amylase, peroxidase, and lysozyme. Lysozyme also acts as an antibacterial agent which is why licking wounds can keep them clean of infection. The number of proteins identified in saliva has increased to around 50 and some of their functions are still unknown.

The inability to produce enough saliva is known as xerostomia and is a symptom of some conditions, including being a side effect of some drugs. Chewing gum is an ideal remedy to stimulate more saliva production.