Diseases & Conditions


Minerals and Electrolytes

Minerals are necessary for the normal functioning of the body's cells. The body needs large quantities of calcium, chloride, magnesium, phosphate, potassium, and sodium. These minerals are called macrominerals. Bone, muscle, heart, and brain function depends on these minerals. The body needs small quantities of chromium, copper, fluoride, iodine, iron, manganese, molybdenum, selenium, and zinc. These minerals are called trace minerals. Except for chromium, all trace minerals are incorporated into enzymes or hormones required in body processes (metabolism). Chromium helps the body keep blood sugar levels normal. All trace minerals are harmful if too much is ingested.

Minerals are an essential part of a healthy diet. The recommended dietary allowance (RDA)—the amount most healthy people need each day to remain healthy—has been determined for most minerals. People who have a disorder may need more or less than this amount.

Consuming too little or too much of certain minerals can cause a nutritional disorder. People who eat a balanced diet containing a variety of foods are unlikely to develop a nutritional disorder or a major mineral deficiency, except for calcium, iodine, or iron deficiency. However, people who follow restrictive diets may not consume enough of a particular mineral (or vitamin). For example, vegetarians, including those who eat eggs and dairy products, are at risk of iron deficiency. Infants are more likely to develop deficiencies because they are growing rapidly (thus requiring large amounts of nutrients).

Consuming large amounts (megadoses) of mineral supplements without medical supervision may have harmful (toxic) effects.

Electrolytes: Some minerals—especially the macrominerals—are important as electrolytes. The body uses electrolytes to help regulate nerve and muscle function and to maintain acid-base balance (see Acid-Base Balance: Introduction ) and fluid balance.

To function normally, the body must keep fluid levels from varying too much in the areas of the body that contain fluid (called compartments). The three main compartments are Fluid within cells Fluid in the space around cells Blood Electrolytes, particularly sodium, help the body maintain normal fluid levels in these compartments (called fluid balance), because how much fluid a compartment contains depends on the concentration of electrolytes in it. If the electrolyte concentration is high, fluid moves into that compartment. If the electrolyte concentration is low, fluid moves out of that compartment. To adjust fluid levels, the body can actively move electrolytes in or out of cells. Thus, having electrolytes in the right concentrations (called electrolyte balance) is important in maintaining fluid balance among the compartments.

The kidneys help maintain electrolyte concentrations by filtering electrolytes from blood, returning some electrolytes, and excreting any excess into the urine. Thus, the kidney help maintain a balance between daily consumption and excretion.

If the balance of electrolytes is disturbed, disorders can develop. An electrolyte imbalance can result from the following: Becoming dehydrated Taking certain drugs Having certain heart, kidney, or liver disorders Being given intravenous fluids or feedings in inappropriate amounts


Doctors can detect many common nutritional disorders or an electrolyte imbalance by measuring the levels of minerals in a sample of blood or urine.



Good Sources

Main Functions

Recommended Dietary Allowance for adults

Safe Upper Limit


Milk and milk products, meat, fish eaten with the bones (such as sardines), eggs, fortified cereal products, beans, fruits, and vegetables

Required for the formation of bone and teeth, for blood clotting, for normal muscle function, for the normal functioning of many enzymes, and for normal heart rhythm

1,000 milligrams

1,200 milligrams for people over 50

2,500 milligrams


Salt, beef, pork, sardines, cheese, green olives, corn bread, potato chips, sauerkraut, and processed or canned foods (usually as salt)

Involved in electrolyte balance

1,000 milligrams


Liver, processed meats, whole-grain cereals, and nuts

Enables insulin to function (insulin controls blood sugar levels)

Helps in the processing (metabolism) and storage of carbohydrates, protein, and fat

35 micrograms for men aged 50 and younger

25 micrograms for women aged 50 and younger

30 micrograms for men over 50

20 micrograms for women over 50


Organ meats, shellfish, cocoa, mushrooms, nuts, dried legumes, dried fruits, peas, tomato products, and whole-grain cereals

Is a component of many enzymes that are necessary for energy production, for antioxidant action*, and for formation of the hormone epinephrine Some Trade Names ADRENALIN , red blood cells, bone, and connective tissue

900 micrograms

10,000 micrograms


Seafood, tea, and fluoridated water

Required for the formation of bone and teeth

3 milligrams for women

4 milligrams for men

10 milligrams


Seafood, iodized salt, eggs, cheese, and drinking water (in amounts that vary by the iodine content of local soil)

Required for the formation of thyroid hormones

150 micrograms

1,100 micrograms


As heme † iron:

Beef, poultry, fish, kidneys, and liver

As nonheme iron: Soybean flour, beans, molasses, spinach, clams, and fortified grains and cereals

Required for the formation of many enzymes in the body

Is an important component of muscle cells and of hemoglobin, which enables red blood cells to carry oxygen and deliver it to the body's tissues

8 milligrams for women over 50 and for men

18 milligrams for women aged 50 and younger (premenopause)

27 milligrams for pregnant women

9 milligrams for breastfeeding women

45 milligrams


Leafy green vegetables, nuts, cereal grains, beans, and tomato paste

Required for the formation of bone and teeth, for normal nerve and muscle function, and for the activation of enzymes

320 milligrams for women

420 milligrams for men


Whole-grain cereals, pineapple, nuts, tea, beans, and tomato paste

Required for the formation of bone and the formation and activation of certain enzymes

2.3 milligrams for men

1.8 milligrams for women

6 to 11 milligrams


Milk, legumes, whole-grain breads and cereals, and dark green vegetables

Required for metabolism of nitrogen, the activation of certain enzymes, and normal cell function

Helps break down sulfites (present in foods naturally and added as preservatives)

45 micrograms

1,100 to 2,000 micrograms


Dairy products, meat, poultry, fish, cereals, nuts, and legumes

Required for the formation of bone and teeth and for energy production

Used to form nucleic acids, including DNA (deoxyribonucleic acid)

700 milligrams

4,000 milligrams


Whole and skim milk, bananas, tomatoes, oranges, melons, potatoes, sweet potatoes, prunes, raisins, spinach, turnip greens, collard greens, kale, other green leafy vegetables, most peas and beans, and salt substitutes (potassium chloride)

Required for normal nerve and muscle function

Involved in electrolyte balance

3.5 grams


Meats, seafood, nuts, and cereals (depending on the selenium content of soil where grains were grown)

Acts as an antioxidant*, with vitamin E

Required for thyroid gland function

55 micrograms

400 micrograms


Salt, beef, pork, sardines, cheese, green olives, corn bread, potato chips, sauerkraut, and processed or canned foods (usually as salt)

Required for normal nerve and muscle function

Helps the body maintain a normal electrolyte and fluid balance

1,000 milligrams

2,400 milligrams


Meat, liver, oysters, seafood, peanuts, fortified cereals, and whole grains (depending on the zinc content of soil where grains were grown)

Used to form many enzymes and insulin

Required for healthy skin, healing of wounds, and growth

15 milligrams

*Antioxidants protect cells against damage due to reactive by-products of normal cell activity called free radicals.

† The body absorbs heme iron better than nonheme iron.

Source: The Merck Manual Home Edition