saliva pH

[DoctorSaul]

What is the nornal pH of saliva in humans?

[Gef]

Stand to be corrected but I think the normal pH of the mouth should be about 7.4, ie slightly alkaline.

[theprof]

This is a difficult question to answer without going into an extraordinary amount of detail. I'll try to keep it concise.

"Normal" saliva can range in pH from about 6.3 to 8.0 and sometimes even above. The actual pH is very dependant on your diet and what you have eaten recently. This is what happens.

When you eat or drink something, nerve endings in the mouth cause a response in the salivatory centres in the brainstem. This results in a flow of saliva into the mouth from the salivary glands. This salivary secretion is under the control of the autonomic nervous system.

The autonomic nervous system is divided into two main divisions, the parasympathetic and sympathetic divisions. Now usually these two divisions are antagonistic to one another, but when it comes to salivation, they work together.

When the parasympathetic nerves are activated, large quantities of ions and enzymes in a very watery saliva are released from the salivary glands. When the sympathetic nerves are stimulated, small quantities of saliva rich in proteins are released from the salivary glands. These two different types of salivas have different pH's.

The result is that the exact pH of saliva is very dependant on the type of activity in the oral autonomic nervous system and it can vary considerably.

(cont)

[theprof]

To complicate matters further, certain oral bacteria (acidogenic bacteria) in dental plaque can metabolise some carbohydrates to acid products. Saliva functions to restore the balance here with the result that the pH can vary depending on the extent of plaque and caries present in the mouth as the additional acidity will cause the mean saliva pH to decrease proportionately. Once the pH decreases to about 5.7 - known as the critical pH - tooth enamel begins to dissolve.

In a healthy mouth, salivary bicarbonate ions raise the pH towards neutrality.

If you tried to pin me down to provide you with a textbook pH, I would tell you 6.5. However, you probably will not have a that exact pH unless you've not eaten or drank anything up to a couple of hours and it can change from one minute to the next in any case.

By the way, some people nowadays are claiming that salivary pH reflects the general state of body health and are advocating certain dubious remedies and procedures to restore this "imbalance" in "mineral depletion. The jury's still out on the case.

[newtron]

After that very detailed explaniation by theprof, I 've decided to offer some real data. I just happen to be in the lab today so I measured the pH of my saliva and it was 7.11. I have not had anything to eat or drink in at least 2 hours. I'll take another measurement in a few hours and report back my findings.

[newtron]

About 4.5 hours later (still haven't eaten anything) pH = 6.82.

[theprof]

By coincidence, I've also been in my lab today. My reading this morning,about 90 minutes after a light breakfast and a brew was 6.864. Unfortunately, the wife dragged me out of the uni around an hour later to take her shopping, so I can't provide a useful second reading.

These reading variations serve to confirm that salivary pH can vary not only between individuals but over a given period in a fasting individual as well. This is in accordance with documented literature available on the subject - it's nice to know we conform.

Whilst in the uni, I also had the chance to look further into the medical diagnoses from these pH readings according to some of these specialised "medical practitioners" in their journals.

You might be interested to know, newtron, that your initial pH is indicative of an individual suffering from excess gas combined with constipation. It also seems that yeasts, moulds and other fungi will be abundant in your body often leading to unexplained symptoms and infections. The good news from other "workers" seems to be that you have an abundance of "minerals" in your body, which is said to be beneficial.

Your second reading appears to indicate that you are a healthy individual!

[newtron]

Hmm, the conflicting diagnoses for the same pH reading and the fact that saliva pH does vary over short time periods does not give me a lot of confidence in using saliva pH as a general health idicator. What do you think theprof?

[theprof]

I don't usually attach much credence to claims of this nature newtron, unless they are provable scientifically

There is no evidence to suggest that this pseudo-scientific interpretation of saliva analysis is sufficiently reliable to provide an indisputable picture of the health of the human body.

The fact that the practitioners of this art interpret the results differently does not assist their cause, although the tendency of saliva pH to alter through the day is not without its drawbacks as far as they are concerned.

I think your right to be sceptical - I know that I am.

This matter came up for discussion at a dinner I attended a few months back. A couple of my colleagues at the table, both professors of medicine, stated quite categorically that these saliva analysis claims are without foundation.