Our bodies are an incredibly complex self-regulating system, made up of different vital organs that each work best at a different level of either acidity or basicity.

When people talk about the ideal pH level for the human body, they tend to use the number 7.4, and so water ionisers and alkaline diets are used to ensure the body maintains that pH level.

Whilst a pH of around 7.4 is normal for the blood, this only tells part of a fascinating story about a body and how it self-regulates systems with vastly different needs.

How Do We Measure Acidity?

Acids and alkaline solutions are measured on a scale between 0 and 14 known as the pH scale, which range from battery acids on the lowest end and drain cleaners on the highest side.

Seven, the middle of the scale, is reserved for pure, distilled water and blood is slightly more alkaline at 7.4 pH.

The issue is modern diets, however, is that they contain a lot of acids. Coffee is quite acidic and orange juice is especially acidic, and so the body needs a way to balance out the different pH levels of different solutions.

What Does The Body Need?

The blood needs to stay around a pH of 7.4, with a blood pH of less than 7.35 being a sign of acidosis, a potentially dangerous disease. The same is true with blood pH levels that are over 7.45, as alkalosis can also cause major issues.

Both of these conditions are rare, and are generally the result of lung and kidney diseases, or consuming large doses of aspirin, baking soda, methanol or antifreeze.

However, pH needs to be seen in terms of the different parts of the body, with some parts of the body having a lower pH value than others.

Stomach acid, for instance, has a pH of between 1 and 2 and the skin has a pH between 4.0 and 6.5 whilst the pancreas and lower digestive system has bile with a pH of up to 8.5.

Because of these vastly different needs, the body has a complex system to ensure that acids and alkalines are neutralised.

The Three Shields

There are three primary ways in which the human body regulates itself, each of which work together to keep the body’s systems in the pH range that keeps them functioning at their best.

The first of these is the use of chemical buffers, most notably bicarbonate. This is released by the kidneys and reacts with acids to turn them into water and carbon dioxide, which the body can easily manage through excretion and respiration, the second line of defence.

Respiration is how the lungs regulate how much carbon dioxide is in the blood, which can then be used to form the bicarbonate we need by reversing the reaction that buffers out acids.

Finally, the last line of defence is the kidneys, which play a vital part in the acid reduction process. They absorb alkalines and acids as needed and maintain a state of homeostasis, as well as produce bicarbonate as it is required.

This is why urine has such a variable pH; the kidneys help to purge out any excess and remove it from the body.