pH is a measure used to determine the acidity or alkalinity of a solution, technically the cologarithm of the activity of dissolved hydrogen ions.

First introduced by the Danish chemist, Soren Peder Laurizt Sorensen, at the Carlsberg university in 1909, the pH scale has been used to measure acidity/alkalinity ever since. According to the scale, water has a pH of 7 and is classified as neutral, while measurements below 7 are considered acidic, and measurements above 7, considered alkaline. The application of the pH scale covers a range of disciplines that include biology, chemistry, the food sciences, environmental studies and oceanography, to name just a few.

What can the pH tell us about our state of health?
The pH scale when applied to a measurement of health measures the acidity or alkalinity of the body’s physiological state. A healthy pH reading can have a range of anywhere from 6.75 to 7.25.

There are two states that can cause the body’s internal balance to go out of sync, and this can result in either alkalosis or acidosis. A short explanation of these conditions is now provided.

• Alkalosis – is where the body’s pH reading is above 7.45. This condition can typically result from hyperventilation, which causes the body to loose carbon dioxide. Metabolic alkalosis can also be caused by prolonged vomiting and the loss of hydrochloric acid from the stomach.
  
  Symptoms of alkalosis: some of the symptoms of alkalosis that have been documented include: confusion, hand tremor, light-headedness, muscle twitching, nausea, vomiting, numbness or tingling in the face, prolonged muscle spasms.
   
• Acidosis – is where the body’s pH reading is below 7.35. Typically this condition results from the build-up of carbon dioxide in the blood, that can come from pulmonary problems - although head injuries, drugs (such as sedatives and anaesthetics) and brain tumours have also been attributed to acidosis.
  
  Symptoms of acidosis: while the symptoms of acidosis should be studies on a case by case basis, typically these can include low energy levels, excess weight, poor digestion, aches and pains, as well as other more serious medical conditions.

The levels of acidity or alkalinity are finely managed by the human body, and acceptable acidity or alkalinity levels can vary from one person to the next. It should also be noted that both the symptoms of acidosis and alkalosis can be associated with other more serious medical conditions so it’s important to make sure you are receiving periodic check-ups with your local doctor as part of an overall medical plan.

For general purpose ‘at home’ analysis there are a number of low cost kits that are available to help you measure your body’s acidity and alkalinity levels. These are a good starting point for the vast majority of people, especially as they are easy to administer and don’t require a doctor’s appointment, or for arrangements to be made to take days off work to attend the testing clinics.
 
pH measurement resources:
 

PH strips to help measure the body’s acidity and alkaline levels [link].

Complete DIY home balancing pH kit [link].

References
Wikipedia: pH, Alkalosis, and Acidosis
Vasey, C., 2006. The Acid Alkaline Diet, Healing Arts Press.