Chloride

Chloride is the primary extracellular anion (Cl⁻) found within the body’s extracellular fluid and is typically found bound to cation sodium as NaCl.¹ Sodium, chloride, and potassium are the main electrolytes that control water balance and action/electric potentials to conduct muscle/nerve impulses.¹

Absorption and Excretion:  Similar to sodium and potassium, chloride absorption rate ranges between 90-95%.¹ Chloride is absorbed in the small intestine and is associated with sodium absorption via a sodium chloride cotransporter but is mostly absorbed by paracellular diffusion.¹ 

Circulation: Chloride is found within extracellular fluid (88%) and intracellular fluid (12%).¹ Specifically, there is 103 mEq/L of chloride in extracellular fluid compared to 4 mEq/L in intracellular fluid.¹ 

Functions: Chloride is an electrolyte that has many functions within the body which include controlling fluid balance, promoting electric neutrality, and synthesizing hydrochloric acid (HCl).¹ Fluid balance is controlled through the difference between the concentration gradient and charge of ions to maintain isotonicity - this is referred to as an electrochemical gradient.¹ Chloride serves as an extracellular anion and neutralizes cation sodium; it is often bound to sodium and follows sodium.¹

The anion bicarbonate (waste product carbon dioxide combined with water) is exchanged for chloride within cells and is called the chloride shift.¹ When bicarbonate builds up inside cells, it eventually diffuses out of the cell and is replaced with anion chloride; the bicarbonate is broken down into water and carbon dioxide to be exhaled by the lungs.¹

Chloride is also found within HCl produced by parietal cells in the stomach; HCl is used to break down food into smaller components.¹ The role of chloride in action/electrical potentials is minimal compared to sodium and potassium but can both inhibit and promote action/electric potentials within neurons and heart cells.¹ Chloride also plays a role in balancing pH levels.³

Dietary Reference Intake (DRI) - The Adequate Intake (AI) for males and females 9-50 years old is 2.3 grams/day.² Males and females between 51-70 years old are recommended to consume 2.0 grams/day, and those 71+ years old or older are recommended to consume 1.8 grams/day.²

Deficiency/Toxicity - The body regulates chloride through renal/kidney processing of ultrafiltrate into urine.  Deficiency and toxicity of chloride is therefore uncommon but is possible for at-risk individuals. Chloride deficiency can occur with diarrhea, vomiting, or excessive diuretic use due to the loss of water and electrolytes termed hypochloremia.³

Consequent dehydration from severe or consistent loss of water can also cause a buildup of electrolytes such as chloride that can lead to hyperchloremia.³ Hyperchloremia can occur with excessive sodium intake.³ Hyperchloremia can cause blood acidosis, high blood pressure, and muscle weakness.³

Dietary Sources of Chloride

Chloride intake is associated with sodium intake due to its bond with sodium as NaCl or table salt. Therefore, foods high in sodium also contain chloride - 1 gram of NaCl contains 400 milligrams of sodium and 600 milligrams of chloride. Chloride levels in fruits, vegetables, meats, and seafood vary but are typically low. It is also found as an additive or preservative in foods.³

Examples of foods containing sodium and chloride include:

Meat/Seafood/Animal Product- ham, hot dogs, bologna, bacon, sardines

Dairy - cheddar cheese, milk, cream-based soups

Grains - crackers, bread, muffins

Vegetables - seaweed, lettuce, celery, tomatoes, olives

Other - soy sauce, french fries, fast food, gravies, broths, pickle

Source(s)

1. Denise M Medeiros and Robert E.C. Wildman, Advanced Human Nutrition, 4th ed. (Burlington, MA: Jones & Bartlett, 2019).

2. https://www.ncbi.nlm.nih.gov/books/NBK545442/table/appJ_tab3/?report=objectonly

3. https://nutritionsource.hsph.harvard.edu/chloride/#:~:text=It%20helps%20to%20regulate%20the,and%20carbon%20dioxide%20within%20cells.