What Is pH Balance?

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The pH balance plays an important role in the chemical makeup of the human body. The term "pH" refers to whether a substance is an acid, an alkaline (also known as basic), or neutral.

In the human body, the pH of bodily fluids, organs, and other components can have an influence on the biochemical reactions that support various functions, such as digestion, metabolism, and hormonal production. Keeping the body's pH balanced allows the body to function in a state of equilibrium or homeostasis.

This article looks at how pH balance works, why pH balance is important for maintaining optimal health, and ways that pH balance might be altered.

pH Test

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Although pH is often something only talked about in chemistry class, it does have significance in terms of the body’s function.

PH is a measure of how acidic or alkaline a substance is. The "H" stands for hydrogen—pH estimates the concentration of the hydrogen ion in a given substance. As technical as that sounds, you don’t need to understand chemistry to understand how pH relates to health. 

A pH balance is important in terms of health because having a stable pH is key to maintaining the body’s everyday functioning. It’s not something that comes up every day as the body is very good at maintaining a healthy pH balance on its own.


The pH range is from zero to 14, with zero being the most acidic, 14 being the most basic, and seven being neutral. In healthy humans, normal body pH is between 7.35 and 7.45, with an average of 7.4.

This slightly alkaline pH level is ideal for many biological processes, such as the oxygenation of blood. However, not all parts of the body are kept in the precise 7.4 range.

For instance, in the stomach, gastric juices range from a pH of 1.35 to 3.5. That is very acidic. The acidity works to create a hostile environment that kills off bacteria and other pathogens, and it also aids in digestion by helping to break down protein and other food particles.

Skin also has an acidic pH. It's between 4 and 6.5. The reason the skin is acidic is to act as a barrier and protect the body from microbes.

How it Works

A pH balance simply means that the acid-base balance in the body is generally maintained. The body needs to stay in homeostasis (a stable state) to function optimally.

When healthy, the body has many different compensatory mechanisms in place to maintain this level, such as filtering blood through the kidney (to remove or retain acids and bases) and regulating breathing (which controls the intake of oxygen and expiration of carbon dioxide through the lungs).

Acids are produced as normal by-products during the process of metabolizing carbohydrates, proteins, and fats, which are then filtered out of the blood by the kidneys and excreted in the urine. Oxygen and electrolytes (minerals like sodium, potassium, and magnesium) are basic and help shift the body to a more alkaline state.

If body pH is less than 7.35, the body is in a state of "acidosis."

If body pH is more than 7.45, the body is in "alkalosis" or "basic."

Associated Conditions

The human body can be out of pH balance in these four main ways:

  • Metabolic acidosis: When the kidneys are unable to remove enough acid from the blood, this pH imbalance can occur. There are different types of metabolic acidosis, depending on the acid that is building up in the body. For example, lactic acidosis is caused by a buildup of lactic acid (a chemical that’s released in vigorous exercise).
  • Metabolic alkalosis: This occurs when there is too much of a chemical called bicarbonate in the blood, which is sometimes an indication of kidney disease.
  • Respiratory acidosis: In this disorder, excess carbon dioxide builds up in the body because not enough is being expelled through breathing. Chest injuries and the overuse of sedative drugs are some causes of respiratory acidosis.
  • Respiratory alkalosis: This condition is caused by not having enough carbon dioxide (an acid) in the blood. A lack of carbon dioxide can be caused by something as simple as being at a high altitude or something as serious as lung disease.

If one of these imbalances occurs, the body will try to compensate by inducing the opposite condition. For instance, if you are in metabolic acidosis, the body will try to counterbalance the state by causing respiratory alkalosis.


PH is the measure of how acidic or basic a substance is. In humans, pH balance plays a role in keeping the body functioning optimally. The ideal pH of the body is slightly alkaline, which facilitates certain biochemical reactions like oxygenating the blood. The body has numerous corrective measures to keep pH in homeostasis (a stable state).

A Word From Verywell

While understanding pH balance can be intimidating as it involves a bit of chemistry, the main takeaway is that maintaining a balance between acids and bases is a normal part of the body’s everyday functioning. While some conditions can affect your body’s pH balance, most times, your body’s pH is not something you need to actively think about.

3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Hopkins E, Sanvictores T, Sharma S. Physiology, acid-base balance. In: StatPearls. Treasure Island (FL): StatPearls Publishing.

  2. Schwalfenberg GK. The alkaline diet: is there evidence that an alkaline pH diet benefits health?J Environ Public Health. 2012:727630. doi:10.1155/2012/727630

  3. MedlinePlus. Acidosis.

By Emily Brown, MPH
Emily is a health communication consultant, writer, and editor at EVR Creative, specializing in public health research and health promotion. With a scientific background and a passion for creative writing, her work illustrates the value of evidence-based information and creativity in advancing public health.