Mineral deficiency is a reduced level of any of the minerals essential to human health. An abnormally low mineral concentration is usually defined as a level that may impair a function dependent on that mineral.
Minerals are essential nutrients for every living cell in the human body. Defined in the study of human nutrition as all the inorganic elements or molecules required for life, minerals assist in body functions such as producing energy, growing, and healing. Minerals are required for fluid balance, blood and bone development, maintaining a healthy nervous system, and regulating muscles, including heart muscles. Minerals, like vitamins , function as coenzymes. They participate in all enzyme reactions in the body and help in the assimilation and use of vitamins and other nutrients.
Minerals occur either as bulk minerals (macrominerals) or trace minerals (microminerals). The body needs more bulk minerals than it does trace minerals, although both are essential for health. Minerals are consumed in food from plants and plant-eating animals. These sources of minerals develop in a sequence that takes millions of years, beginning with rock formation, the breakdown of rocks into mineral salts, and the assimilation of these salts into soil that nourishes edible plants.
Recommended daily allowances exist for a number of minerals, such as calcium. However, minimum daily requirements for some minerals such as boron, chromium, and molybdenum, do not exist. The essential bulk minerals include:
- Calcium—essential for strong bones and teeth, healthy gums, and bone growth and mineral density in children. Calcium helps regulate the heart rate and nerve impulses, lower cholesterol, prevent atherosclerosis, develop muscles, and prevent muscle cramping. Calcium is an important component of blood clotting. Calcium and phosphorus are closely related minerals that should be balanced. About 99 percent of calcium and 85 percent of phosphate occur in the skeleton as crystals of calcium phosphate. Both nutrients occur in a variety of foods such as milk, eggs, and green, leafy vegetables. Calcium deficiency due to lack of dietary calcium occurs only rarely and is often due to vitamin D deficiency , because vitamin D is required for efficient absorption of dietary calcium. Significant depletion of calcium stores can lead to osteoporosis.
- Magnesium—assists in the utilization of calcium and potassium, and functions in enzyme reactions to produce energy. Magnesium protects the lining of arteries and helps form bones. It helps prevent cardiovascular disease, osteoporosis, and some cancers. By acting with vitamin B 6 , magnesium can help prevent or dissolve calcium oxylate kidney stones, the most common kind of stones. Dietary magnesium deficiency is uncommon, but may occur in chronic alcoholics, persons taking diuretic drugs, and as a result of severe, prolonged diarrhea .
- Sodium—sodium deficiency (hyponatremia) is a serious deficiency, arising most often after excessive losses of body fluid ( dehydration ) during prolonged and severe diarrhea or vomiting . Sodium and potassium are electrolytes that must be balanced in the body. Since most people get more than enough salt in the diet, potassium may be needed to balance it. Together, these minerals control fluid balance through a mechanism called "the sodium/potassium pump." Prolonged imbalances in sodium and potassium can contribute to heart disease.
- Potassium—important for a healthy nervous system and a steady heart rate, helps to prevent stroke , and, with sodium, is critical in maintaining fluid balance. Potassium, an electrolyte, must be balanced with sodium. Potassium deficiency is usually associated with sodium deficiency and both are associated with dehydration stemming from excessive losses of body fluid.
- Phosphorus—helps form bones and teeth, supports cell growth, and regulates heart muscle contraction and kidney function. Phosphorus converts food to energy and supports the utilization of vitamins. Deficiency is rare because phosphate is plentiful in plant and animal foods and is efficiently absorbed from the diet. Phosphorus is closely related to calcium and the two minerals should be in balance with each other and with magnesium. Deficiency in one will affect all and will ultimately have an unwanted effect on body function. Calcium and phosphorus are stored in the bones as crystals of calcium phosphate. Milk, eggs, and green, leafy vegetables are rich in calcium and phosphate.
Trace minerals essential for human health include:
- Boron—required for healthy bones, brain function, alertness, and the metabolism of bulk minerals such as calcium, phosphorus, and magnesium. Deficiencies are rare except in aging, when supplementation may help absorb calcium. A deficiency in boron is associated with vitamin D deficiency. Boron supplements can improve calcium levels as well as vitamin D levels, and can help prevent osteoporosis in postmenopausal women by promoting calcium absorption.
- Chromium—required for maintaining energy levels. Chromium helps metabolize glucose and stabilize glucose levels. It helps the body manufacture and use cholesterol and protein.
- Copper—helps form healthy bones, joints, and nerves as well as hemoglobin and red blood cells. Copper contributes to healing, energy production, taste, and hair and skin color. It is essential in forming collagen for healthy bones and connective tissue, and helps prevent osteoporosis. Except in osteoporosis, copper deficiency is rare, although dramatic changes in copper metabolism occur in two serious genetic diseases, Wilson disease and Menkes' disease.
- Germanium—helps improve the delivery of oxygen to tissues and remove toxins and poisons from the body. Germanium gives garlic its natural antibiotic properties.
- Iodine—helps promote healthy physical and mental development in children. Iodine is required for thyroid gland function and metabolizing fats. Iodine deficiency is a public health problem in parts of the world that have iodine-deficient soils. Iodine is needed to make thyroid hormone, which has a variety of roles in human embryo development. A deficiency during pregnancy can cause serious birth defects. Deficiency in adults can result in an enlarged thyroid gland (goiter) in the neck.
- Iron—critical in the production of hemoglobin, the oxygen-carrying protein in red blood cells, and myoglobin found in muscle tissue. Iron is essential for important enzyme reactions, growth, and maintaining a healthy immune system. In the blood, iron is found in larger amounts than any other mineral. Iron deficiency causes anemia (low hemoglobin and reduced numbers of red blood cells), which results in tiredness and shortness of breath because of poor oxygen delivery.
- Manganese—essential for metabolizing fat and protein, regulating blood glucose, and supporting immune system and nervous system function. Manganese is necessary for normal bone growth and cartilage development. It is involved in reproductive functions and helps produce mother's milk. Along with B vitamins, manganese produces feelings of well-being. Deficiency can lead to convulsions, vision and hearing problems, muscle contractions, tooth-grinding and other problems in children; and atherosclerosis, heart disease, and hypertension in older adults.
- Molybdenum—found in bones, kidneys, and liver. Only extremely small amounts are needed to metabolize nitrogen and promote proper cell function. Molybdenum is present in beans, peas, legumes, whole grains, and green leafy vegetables. A diet low in these foods can lead to mouth and gum problems and cancer.
- Selenium—an important antioxidant that works with vitamin E to protect the immune system, heart, and liver, and may help prevent tumor formation. Selenium deficiency occurs in regions of the world where soils are selenium-poor and low-selenium foods are produced. Premature infants are naturally low in selenium with no known serious effects.
- Silicon—helps form bones and connective tissue, nails, skin, and hair. Silicon is important in preventing cardiovascular disease.
- Sulfur—disinfects the blood and helps to rid the body of harmful bacteria and toxic substances.
- Vanadium—vital to cell metabolism, and helps reduce cholesterol and form healthy bones and teeth. Vanadium functions in reproduction. Deficiencies may be associated with heart and kidney disease and reproductive disorders. Vanadium deficiency may be associated with infant mortality.
- Zinc—important in the growth of reproductive organs and regulation of oil glands. Zinc is required for protein synthesis, immune system function, protection of the liver, collagen formation, and wound healing. A component of insulin and major body enzymes, zinc helps vitamin absorption, particularly vitamins A and E. Deficiency is rare.
Trace and bulk minerals are stored in muscles and bones and delivered to tissue cells through blood circulation. They work together synergistically and must be chemically balanced in the body; if one is deficient or out of balance, it can affect all the others, often resulting in illness. If zinc, for example, is present at high levels, calcium levels will be reduced because the two minerals compete for absorption. Similarly, too much calcium will deplete magnesium, and so on. Deficiency in one nutrient occurs less often than deficiency in several nutrients. A child suffering from malnutrition will likely be deficient in a variety of nutrients. Deficiencies in one nutrient do occur, however, such as in populations living in iodine-poor regions, and in iron deficient persons who lose excess iron by abnormal bleeding. All uncorrected mineral deficiencies can affect body functions, produce symptoms, and result in illness.
Statistics are not available for most individual mineral deficiencies, most likely because such deficiencies are rare in the United States. Surveys of lower-income families in the United States reveal that about 6 percent of infants are anemic, indicating a possible deficiency of iron in the diet (all anemias are not iron-deficiency related).
Diarrheal diseases and related sodium and potassium deficiencies are responsible for about two million infant deaths each year worldwide. Few of these deaths occur in the United States.
Causes and symptoms
Calcium and phosphorus deficiencies
Calcium and phosphorus are plentiful in foods, and dietary deficiencies are rare. Vitamin D deficiency impairs the absorption of dietary calcium and can provoke calcium deficiency (hypocalcemia) even when adequate calcium is consumed. Vitamin D deficiency can be found among young infants and the elderly who may be shielded from sunshine for prolonged periods. As women age, reductions in the hormone estrogen can affect the rate of calcium loss. Significant depletion of calcium stores can lead to osteoporosis. Deficiency of calcium or imbalances with phosphorus and magnesium can produce muscle cramping and digestive problems. Symptoms of calcium deficiency include joint pain , brittle nails, eczema, high cholesterol , insomnia, high blood pressure, nervousness, and tooth decay . Calcium deficiency can also contribute to cognitive problems (confusion, inattention, learning, and memory), convulsions, depression, and hyperactivity. Phosphorus deficiency can produce anxiety .
Sodium and potassium deficiencies
Deficiency or imbalance in sodium and potassium does not usually result from a lack of these minerals in the diet, but from imbalances in body fluids. This can be caused by excessive losses of body fluid (dehydration) from severe diarrhea or vomiting; laxative abuse; or during treatment of heart disease or high blood pressure (hypertension) with diuretic drugs, which are used to reduce fluid overload. Sodium and potassium imbalances can cause cardiac arrhythmias and shock (a reduced flow of blood and oxygen to tissues throughout the body). Although diarrheal fluids deplete a number of electrolytes (sodium, potassium, chloride, calcium, phosphorus, and magnesium), the main concern in avoiding shock is replacing sodium and water. Potassium deficiency alone can also affect nerve function.
Dietary magnesium deficiency is rare because the mineral is found in nearly all foods, but it can occur through poor diet or in malnutrition, or result from excessive losses due to severe diarrhea or vomiting. Symptoms of magnesium deficiency include faulty transmission of nerve and muscle impulses, irritability, nervousness, and tantrums . Confusion, poor digestion, rapid or irregular heartbeat (arrhythmia), and seizures can also result. Magnesium deficiency is associated with cardiac arrest, asthma , chronic fatigue syndrome, chronic pain, depression, insomnia, irritable bowel syndrome , and lung conditions.
Boron deficiency is rare, although reduced levels do occur with aging and with reduced levels of vitamin D. Because boron is involved in the absorption of calcium, the only symptom may be reduced levels of calcium or the inability to absorb supplemental calcium.
Many Americans are deficient in dietary chromium, which can be associated with poor regulation of insulin and related imbalances in glucose (either diabetes or hypoglycemia ). Symptoms include fatigue, anxiety, poor protein metabolism, and glucose intolerance (as in diabetes). In adults, chromium deficiency can be a sign of coronary artery disease.
Copper is obtained through a balanced diet and deficiency is rare. Signs of copper deficiency may include anemia, diarrhea, weakness, poor respiratory function, baldness, skin sores, and increased lipid (fat) levels in the blood. Severe alterations in copper metabolism are seen in two rare genetic diseases: Wilson disease and Menkes' disease, which occur in about one in 100,000 births. Both diseases involve mutations in copper transport proteins, special channels that allow copper ions to pass through cell membranes. Menkes' disease, called the "kinky hair disease," results in tangled, grayish, steely, or kinky hair and chubby, rosy cheeks. Untreated Menkes' disease is associated with mental retardation and death before three years of age. Wilson disease involves decreases in copper in blood cells, the liver and brain; and increases in copper (copper toxicosis) in the cells of the intestines and kidneys. It results in degenerative changes in the brain, liver disease, and hemolytic anemia. Children older than five years who have any form of liver disease are often evaluated for serum and cellular copper levels to determine if Wilson disease is present.
Germanium deficiency is rare; in fact, there is no established deficiency level.
Iodine deficiency occurs when soil is iodine-poor and foods grown in the soil are correspondingly low in iodine. An iodine intake of 0.10–0.15 mg/day is considered to be nutritionally adequate. Iodine deficiency occurs when intake is below 0.05 mg/day. Goiter, an enlargement of the thyroid gland in the neck, results from iodine deficiency. Although goiter continues to be a problem in other parts of the world, it no longer occurs in the United States because of the fortification of foods with iodine. Iodine deficiency during pregnancy can result in cretinism in newborns, involving mental retardation and a large tongue.
Iron deficiency occurs most often because of poor iron intake and poor absorption. In children, iron deficiency is due to periods of dietary deficiency and heavy demands for iron during rapid growth. Human milk and cow's milk both contain low levels of iron; however, the iron in human milk is in a highly absorbable form. Infants are at risk for acquiring iron deficiency because their rapid rate of growth needs a corresponding increased supply of dietary iron, for use in making blood and muscles. Cow's milk formula is fortified with iron. Human milk is a better source of iron than cow's milk, since about half of the iron in human breast milk is absorbed by the infant's digestive tract. In contrast, only 10 percent of the iron in cow's milk is absorbed by the infant. Toddlers who drink excessive whole cow's milk are at risk for iron deficiency. Iron deficiency can also be caused by excess phosphorus in the diet, chronic intestinal bleeding, poor digestion and absorption, prolonged illness, ulcers, and the use of antacids. In women and teenage girls, blood loss through menstruation can result in iron deficiency. Symptoms of iron deficiency include anemia and resulting fatigue and weakness, especially during physical exertion. Fragile bones, brittle hair and nails, hair loss, spoon-shaped fingernails or ridges from the base of the nails to the ends, difficulty swallowing, nervousness, paleness, and lagging mental responses are also possible iron deficiency symptoms.
Deficiency of manganese is very rare. Experimental studies of individuals fed a manganese deficient diet have revealed that the deficiency produces a scaly, red rash on the skin of the upper torso.
Selenium deficiency may occur in premature infants who naturally tend to have about one-third the selenium levels of full-term infants. It is not known if these lower levels result in adverse consequences. Selenium deficiency occurs in regions of the world containing low-selenium soils, including parts of China, New Zealand, and Finland. In Keshan Province, China, a condition (Keshan disease) occurs that results in deterioration of regions of the heart and the development of fibers in these areas. Keshan disease, which may be fatal, is thought to result from a combination of selenium deficiency and a virus.
Zinc deficiency can be caused by diarrhea, liver and kidney disease, alcoholism , diabetes, malabsorption, and overconsumption of fiber. Symptoms of zinc deficiency include acne , recurrent colds and flu, loss of senses of taste and smell, poor night vision, slow growth, lack of sexual maturation, lack of pubic hair, and small stature. Studies have shown that signs of zinc deficiency are detectable after two to five weeks of consuming a zinc-free diet. Signs include a rash on the face, groin, hands and feet, and diarrhea. Administering zinc will correct these symptoms.
When to call the doctor
Mineral deficiencies present with a wide variety of symptoms. Parents should observe children closely and report any unusual symptoms to the pediatrician, such as tiredness, weakness, depression or anxiety, irritability, nervousness, skin irritations, dehydration from vomiting or diarrhea, and slow growth or development of skills. Other than providing regular vitamin supplements and a balanced diet to prevent deficiencies, parents should not attempt to diagnose and treat deficiencies on their own.
Individual minerals can be measured in blood serum, red blood cells, tissue cells, or urine, to estimate available levels and determine normal or abnormal status. Since each mineral performs strikingly different functions, tests to confirm deficiency are markedly different from each other. Testing can range from simple to extensive. Physicians will consider the possible consequences of each type of deficiency and evaluate the function of organ systems affected by the particular mineral.
In addition to determining serum calcium, phosphorus, and vitamin D levels, the diagnosis of calcium and phosphorus deficiency may involve taking x rays of the skeleton.
Diagnosing iron deficiency will require measuring iron levels and investigating anemia by performing blood tests such as a complete blood count (CBC) to determine the number of red blood cells, hemoglobin level, red cell volume, and cell maturity (morphology). A stair-stepping test may be used to evaluate stamina, but a blood test is required to diagnose iron deficiency.
Diagnosing low levels or imbalances of the electrolytes sodium, potassium, calcium, magnesium, or phosphate involves measuring the serum levels of each. Measurement determines the circulating blood level at the time blood was drawn. Laboratory values of sodium and potassium, which are present within cells and in the fluid between cells, can change rapidly depending on the individual's overall condition. They may be measured repeatedly to determine a trend and to monitor correction of the deficiency or imbalance after diagnosis.
Normal serum magnesium levels are 1.2–2.0 mE/l, while levels in deficiency (hypomagnesemia) are below 0.8 mE/l. Because calcium and magnesium must remain balanced, magnesium levels below 0.5 mE/l can provoke a decline in serum calcium levels. Hypomagnesemia can also result in low serum potassium. Symptoms of hypomagnesemia, such as twitching and convulsions, may actually result from the hypocalcemia. Other symptoms, such as cardiac arrhythmias, actually occur because of low potassium. All three minerals will be measured.
Iodine deficiency is diagnosed by measuring the concentration of iodine in urine. A urinary level greater than 0.05 mg iodine per gram of creatinine (another metabolite excreted in urine) indicates adequate iodine status. Levels under 0.025 mg iodine/gram creatinine indicate serious risk. The doctor may also examine the neck with the eyes and hands to see if a goiter is present.
Urinary zinc levels will differ between normal dietary intake (16 mg per day) and low-zinc diets (0.3 mg per day); normal urinary zinc is about 0.45 mg per day while low-zinc urinary levels are about 0.150 mg per day. Plasma zinc levels tend to be maintained during a dietary deficiency in zinc. Plasma and urinary zinc levels can be influenced by a variety of factors, and for this reason cannot provide a clear picture of zinc status.
Selenium can be measured in plasma or red blood cells and compared to normal values. The activity of an enzyme (glutathione peroxidase) in platelets (small blood cells essential in blood clotting) may be evaluated to assess selenium status.
Most mineral deficiencies can be successfully treated through diet or supplementation, except when caused by disease, which requires treatment of the disease.
Treating fluid imbalances and related deficiencies in sodium, potassium, calcium, and phosphate usually requires intravenous (IV) infusion of the deficient mineral in fluid over a period of time. Sudden changes in sodium and potassium levels can be just as dangerous as low levels; caution is used to restore balance gradually. Children may be given oral pediatric preparations to gradually restore fluids and minerals.
Iron deficiency requires oral supplementation or injectable iron. Vitamin C helps to assimilate iron.
Iodine deficiency is easily treated and prevented by consuming foods fortified with iodine, such as table salt. Goiter is reversible with treatment but cretinism is not.
A magnesium-rich diet will correct magnesium deficiency. If deficiency is due to prolonged depletion, treatment may include injections of magnesium sulfate; if severe enough to provoke convulsions, intravenous infusions may be given.
Selenium deficiency can be treated by supplementation. Children can be given supplements containing 1.0 mg sodium selenite.
Zinc and copper deficiencies are rare and can be treated with supplementation.
The prognosis for mineral deficiencies depends on the extent of deficiency at diagnosis, the degree of effects or symptoms, and the overall health of the individual. Correction through diet or supplements usually produces good results. Symptoms may sometimes be relieved promptly with supplementation. Some deficiencies produce permanent effects of varying severity.
In iodine deficiency, the prognosis for treating goiter is excellent. Sodium and potassium deficiencies or imbalances can be corrected if diagnosed and treated promptly, but can be life-threatening if untreated. Anemia and other effects of iron deficiency are not usually life-threatening and can be corrected with supplementation. "Silent" or undiagnosed calcium loss may result in osteoporosis, which may produce disability or complications by the time it is diagnosed.
Sea vegetables (sea weeds such as dulse, kelp, wakambe, and hijiki) are an excellent source of minerals obtained from the ocean. They can be used to make soup stock, added to stews and casseroles, or served with vegetables. Herbs are a valuable source of minerals as well. For example, calcium is found in alfalfa, burdock root, chamomile, dandelion, flaxseed, paprika, raspberry leaves, rose hips, and other herbs. Iron is found in the same herbs as calcium, and in the Chinese herb dong quai (angelica), as well as other herbs.
Ensuring an adequate intake of essential nutrients through a balanced diet and supplements is the best way to prevent mineral deficiencies. The Required Dietary Allowances (RDA) guidelines can help ensure that minerals are being obtained. Safe amounts of certain minerals are often included in multivitamins. Because excess mineral levels can also cause health problems, taking excessive amounts of any mineral supplement is not advised unless a deficiency is diagnosed. When mineral deficiency is the result of disease, medical attention, other than preventive measures, is required.
A balanced diet includes fresh vegetables and fruits, legumes, whole grains (cereal, bread, rice, pasta, and other grains), eggs, dairy products, fish, fowl, and lean meat as preferred. A diet high in refined foods, prepared foods, sugars, and fats will not provide sufficient quantities of essential minerals. Water delivers nutrients throughout the body; it is essential to drink enough clean water daily to maintain fluid balance and distribute nutrients.
Essential mineral nutrients are found in a variety of sources, as in these examples:
Electrolytes —Salts and minerals that produce electrically charged particles (ions) in body fluids. Common human electrolytes are sodium chloride, potassium, calcium, and sodium bicarbonate. Electrolytes control the fluid balance of the body and are important in muscle contraction, energy generation, and almost all major biochemical reactions in the body.
Nutrient —Substances in food that supply the body with the elements needed for metabolism. Examples of nutrients are vitamins, minerals, carbohydrates, fats, and proteins.
Osteoporosis —Literally meaning "porous bones," this condition occurs when bones lose an excessive amount of their protein and mineral content, particularly calcium. Over time, bone mass and strength are reduced leading to increased risk of fractures.
Recommended Dietary Allowance (RDA) —The Recommended Dietary Allowances (RDAs) are quantities of nutrients in the diet that are required to maintain good health in people. RDAs are established by the Food and Nutrition Board of the National Academy of Sciences, and may be revised every few years. A separate RDA value exists for each nutrient. The RDA values refer to the amount of nutrient expected to maintain good health in people. The actual amounts of each nutrient required to maintain good health in specific individuals differ from person to person.
- Boron is abundant in apples, pears, grapes, leafy greens, carrots, whole grains, and nuts.
- Primary calcium sources are dairy foods, eggs, fish, and green leafy vegetables. Other calcium-rich foods are figs, broccoli, cabbage, oats, almonds and filberts, yogurt, and blackstrap molasses. Spinach and Swiss chard bind calcium in the digestive tract and are not a ready source.
- Chromium is found in brown rice and other whole grains, cheeses, meats, dried beans, corn, eggs, mushrooms, and potatoes.
- Copper is found in nuts, mushrooms, broccoli, garlic, lentils, salmon, and green vegetables. It is also found in plumbing and cooking pots, which may leach into food and water.
- Germanium occurs primarily in garlic, shiitake mushrooms, and onions.
- Iron can be provided by eating green leafy vegetables, raisins, meat, eggs, liver, fish and fowl, nuts, and whole grains. It can also be obtained by cooking in iron skillets.
- Magnesium is found in most foods, primarily animal and fish sources.
- Potassium food sources include dairy foods, fish, fresh and dried fruits, beans and peas, meats, fish and fowl, and whole grains.
- Zinc sources include brewer's yeast, eggs, fish, meats, beans, mushrooms, nuts and seeds, and whole grains.
Good nutrition is a concern of all parents. In the United States, it is relatively easy to provide a balanced diet with essential nutrients if a wide variety of whole foods are prepared for family meals and snacks, while avoiding refined and prepared foods high in fats and sugars. RDA guidelines and public health resources can help assure parents that they can prevent dietary deficiencies in their young children and teens.
Balch, James, and Phyllis Balch. Prescription for Nutritional Healing, 3rd ed. New York: Avery Publishing Group, 2002.
Brody, Tom. Nutritional Biochemistry. San Diego: Academic Press, 1998.
American Society for Nutritional Sciences (ASNS). 9650 Rockville Pike, Suite 4500, Bethesda, MD 20814. (301) 634-7050. Web site: http://www.nutrition.org.
Food and Nutrition Information (FNIC). [cited October 9, 2004]. Available online at: http://www.nal.usda.gov/fnic/.
L. Lee Culvert Tom Brody, Ph.D.