Chloride is a salt consisting of two elements, one of which is chlorine. Chloride makes up about 0.15% of the body weight and is found in the extracellular fluid, along with sodium.

Chloride is essential in the maintenance of the body's acid-base and fluid balance. It is an essential component of the gastric (digestive) juices.

Chloride is mainly obtained from table salt or sea salt, which is primarily sodium chloride. It is also found in many vegetables. Foods with higher amounts of chloride are seaweed, rye, tomatoes, lettuce, celery, and olives. Potassium chloride is found in most foods and is usually the main ingredient of salt substitutes.

Increased intake of chloride in the form of salt can cause fluid retention, but this is primarily because of the sodium in the salt, not the chloride.

A deficiency of chloride can be caused by fluid loss as a result of excessive sweating, vomiting, or diarrhea. Use of medications such as diuretics can also cause a deficiency. This loss of chloride can result in excessive alkalinity of the body fluids (alkalosis), low fluid volume (dehydration), and loss of potassium in the urine.

There are no recommended dietary allowances for chloride. It is readily available in the food supply. In fact, most Americans probably consume more chloride than necessary, in the form of added table salt and excessive salt in processed foods.