MINERALS AND TRACE MINERALS

V. MINERALS AND TRACE MINERALS

Minerals are inorganic elements that retain their chemical identity when in a food product.

minerals are those present in amounts larger than 5 g in the human body. The seven major minerals include calcium, phosphorus, potassium, sulfur, sodium, chloride, and magne- sium. Sulfur, however, is not traditionally used as a nutritional additive. There are more than a dozen trace minerals. Some of the most important trace mineral nutritional additives include iron, zinc, copper, iodine, manganese.

Mineral additives are commercially available in one or several salt forms. Some minerals, including iron, are available in the elemental form. Aside from price consider- ations, the choice of the source depends on three factors:

1. Bioavailability of the mineral in a particular salt form

2. Solubility and/or mixability

3. Potential effects on final product properties Minerals cannot be destroyed by heat, air, acid, or mixing, and only little care is

needed to preserve minerals during food preparation. The ash that remains when a food is burned contains the minerals that were in the food originally.

A. Calcium

Calcium is needed to form bones and to keep bones strong. Bones and teeth are the major storage units of calcium of one’s body. Bones are continually torn down and built back as the body works to meet its calcium needs. If calcium needs are not met through dietary intake, the body will pull greater amounts of calcium from bones. Without adequate intake of calcium, use of stored calcium will lead to porous bones and eventually to the crippling bone disease osteoporosis. Dairy products are an excellent source of calcium. Other sources include dark green leafy vegetables, broccoli, spinach, sardines, canned salmon, and almonds. Recommended Dietary Allowances for calcium have been increased to 1300 mg for ages 9–18, 1000 mg for ages 19–50, and 1200 mg for age 50 and older (145).

Researchers have found that it may be beneficial to start efforts to increase calcium intake early in development, prior to the physical changes associated with puberty (146). As children move to adolescence, their awareness of the importance of calcium increases. Educational factors must focus on increasing specific information about daily requirements and calcium content of various dietary sources (147). As the aging process continues, individuals’ fears about lactose maldigestion or perceptions of dairy products being fat- tening should be addressed (148). Education must continue about the risk of osteoporosis and the ability to meet one’s needs either through dietary intakes or use of supplemental calcium.

Calcium is commercially available in several forms as a nutrient in foods. Calcium phosphate, monobasic: anhydrous (CAS: 7758-23-8) and monohydrate

(CAS: 10031-30-8). Occurs as white crystals, granules, or granular powder and is sparingly soluble in water and is insoluble in alcohol.

Calcium phosphate, tribasic (CAS: 7758-87-4). This white, odorless, tasteless pow- der is stable in air. It is insoluble in alcohol and almost insoluble in water. Dis- solves readily in dilute hydrochloric and nitric acids.

Calcium acid pyrophosphate (no CAS). This is a fine, white, colorless and acidic powder. It is insoluble in water, but does dissolve in dilute hydrochloric and nitric acids.

Calcium carbonate (CAS: 471-34-1). This fine, white microcrystalline powder is Calcium carbonate (CAS: 471-34-1). This fine, white microcrystalline powder is

Calcium glycerophosphate (CAS: 27214-00-2). This fine, white, odorless, almost tasteless powder is somewhat hygroscopic. Greater solubility in water at lower temperatures, and citric acid increases solubility in water. Insoluble in alcohol.

Calcium lactobionate (CAS: 5001-51-4). This is a white to cream colored, odorless,

free-flowing powder that has a bland taste and readily forms double salts. Calcium oxide (CAS: 1305-78-8). This comes as hard, white or grayish white masses or granules, or as white to grayish white powder. It is odorless and soluble in glycerin and insoluble in alcohol.

Calcium phosphate, dibasic: anhydrous (CAS: 7757-93-9) and dihydrate (CAS: 7789-77-7). These are white, odorless, tasteless powders that are stable in air. Calcium pyrophosphate (CAS: 7790-76-3). This is a white, odorless and tasteless powder. It is soluble in dilute hydrochloric and nitric acid and insoluble in water. Calcium sulfate: anhydrous (CAS: 7778-18-9). This fine, white to slightly yellow white, odorless powder is anhydrous or contains two molecules of water of hydra- tion.

Other commercial forms of calcium exist: calcium silicate, calcium acetate, calcium bromate, calcium chloride, calcium gluconate, calcium hydroxide, and calcium peroxide. However, in the Federal Commercial Codex, their functional use in foods does not include the term nutrient (149,150).

Calcium is determined using either atomic absorption spectrometry or inductively coupled plasma spectroscopy. The calcium content in foods may also be determined by permanganate titration. After initial preparation of calcium to an ash solution, it is then precipitated at a pH of about 4 as the oxalate. The oxalate is then dissolved in sulfuric acid to liberate the oxalic acid. The oxalic acid is then titrated with standard potassium permanganate solution (151).

B. Phosphorus

Following calcium, phosphorus is the second major component of bone and teeth. Besides working with calcium, phosphorus is important as a major regulator of energy metabolism in one’s body organs and generates energy in every cell of one’s body. Phosphorus also plays an important role in DNA and RNA (152). Most foods contain phosphorus. However, good sources are protein-rich foods including milk, meat, poultry, fish, and eggs. Legumes and nuts are good sources as well. Carbonated beverages also contain phosphorus. With such an abundance of availability to phosphorus, deficiencies are rare. Should deficiency occur, symptoms would include loss of appetite, bone loss, weakness, and pain. Clinical deficiencies may result from those patients on long-term administration of glucose or total parenteral nutrition without sufficient phosphate. Other concerns are those that have exces- sive use of phosphate-binding antacids, hyperparathyroidism, diabetic acidosis, or alcohol- ism. Premature infants fed unfortified human milk may also develop hypophosphatemia (153). Calcium and phosphorus can have an inhibitory effect on the absorption of iron from food. However, healthy full-term infants fed calcium-, phosphorus-, and iron-fortified formula were found to have no problems with iron deficiency (154).

With excessive intake of phosphorus, the level of calcium in blood may be reduced. This may be a potentially serious problem in those that already have low calcium intake.

progresses. Modifying the protein and phosphorus diets of these patients can be a means to slow the progression of renal insufficiency (155).

The recommended dietary allowances for phosphorus were decreased in 1997. The current recommendations for males and females 9 to 18 years of age is 1250 mg and for males and females 19 years of age and beyond is 700 mg (156).

Commercially phosphorus is available in combination with other minerals: calcium phosphate, calcium pyrophosphate, calcium glycerophosphate, ferric phosphate, ferric py- rophosphate, magnesium phosphate, manganese glycerophosphate, potassium glycero- phosphate, sodium phosphate, sodium ferric pyrophosphate, and sodium pyrophosphate (157).

The Food and Drug Administration has a yearly program, the Total Diet Study, that measures mineral content in representative diets of specific age–sex categories. Analysis of phosphorus content was conducted in 1974–1976 and 1978–1979 using colormetric methods, and then, beginning in 1982, inductively coupled plasma spectroscopy was intro- duced (158). For the purpose of determination of total phosphorus in commercial food oils, graphite furnace atomic absorption provides a rapid and relatively sensitive measure (159).

C. Magnesium

Magnesium is an intracellular cation largely found in bone, followed by muscle, soft tis- sues, and body fluids. It is important for the part that it plays in more than 300 body enzymes. Enzymes regulate body functions, including producing energy, making body protein, and enabling muscle contractions. Magnesium also plays a part in neuromuscular transmission and activity and works with or against the effects of calcium. Excess magne- sium will inhibit bone calcification (160).

Dietary sources high in magnesium include seeds, nuts, legumes, and unmilled ce- real grains. Green vegetables are also good sources. Diets high in refined foods, meats, and dairy products are low in magnesium. In the processing of foods like flour, rice, and sugar, magnesium is lost and not returned in the enrichment process.

Because magnesium is relatively common, deficiencies are rare. In cases where the body does not absorb magnesium appropriately, deficiency symptoms of irregular heart- beat, nausea, weakness, and mental derangement may result. Low magnesium intakes or magnesium deficits in the older population have been linked to various disease states, including ischemic heart disease, hypertension, osteoporosis, glucose intolerance, diabetes, and stroke (161). Because there are no clinical manifestations of magnesium deficiency, it is the most overlooked electrolyte alteration among hospital in-patients (162). Magnesium deficiencies are also common in short bowel syndrome where there is binding of calcium and magnesium, as well as with diseases that cause prolonged vomiting or diarrhea (163). Excessive intakes of magnesium do not appear to be of concern unless kidney disease exists (164).

Recommended dietary allowances for males 19 to 30 years old is 400 mg, and from

31 years on is 420 mg. Recommendations for females 19 to 30 years old is 310 mg, and from 31 years on is 320 mg (165). Commercial forms of magnesium include (166):

Magnesium gluconate: anhydrous (CAS: 3632-91-5) and dihydrate (CAS: 59625- Magnesium gluconate: anhydrous (CAS: 3632-91-5) and dihydrate (CAS: 59625-

Magnesium phosphate, tribasic (CAS: 7757-87-1). This white, odorless, tasteless, crystalline powder may contain four, five, or eight molecules of water of hydra- tion. It is soluble in dilute mineral acids and almost insoluble in water.

Magnesium sulfate (CAS: 7487-88-9). This colorless crystal or granular crystalline powder is odorless. May be produced with one or seven molecules of water of hydration or in dried form containing equivalent of about 2.3 waters of hydration. It is readily soluble in water, slowly soluble in glycerine, and sparingly soluble in alcohol.

An integrated analytical scheme involving flame atomic absorption and flame emis- sion spectrometry can be used to determine magnesium elements in foods (167). The Food and Drug Administration’s Total Diet Study used atomic absorption spectrometry in their analysis of magnesium in foods for the years 1976–1977 and 1980–1995. Inductively coupled plasma spectroscopy was also used beginning in 1982 (168).

D. Potassium, Sodium, and Chloride

These three minerals are known as electrolytes because of their ability to dissociate into positively and negatively charged ions when dissolved in water. These ions, in delicate balance, help to regulate fluids in and out of body cells.

Potassium, the major cation of intracellular fluid, is present in small amounts in extracellular fluid. With sodium, potassium maintains normal water balance, osmotic equi- librium and acid–base balance. Besides helping to regulate fluids in and out of body cells, potassium is also important, along with calcium, in the regulation of neuromuscular activ- ity. Potassium promotes cellular growth and helps maintain normal blood pressure. Muscle mass and glycogen storage are related to muscle mass. During times of muscle formation an adequate supply of potassium is essential. Muscle contractions require potassium.

A wide range of food sources provide potassium including bananas, whole milk, turkey, haddock, okra, oranges, and tomatoes. Concerns involving too much potassium are rare except in cases where the kidneys are unable to excrete excess, which may lead to heart problems. In cases of excessive vomiting and diarrhea, potassium deficiency may result. Deficiency symptoms may include weakness, appetite loss, nausea, and fatigue. Low potassium (hypokalemia) is one of the most common electrolyte abnormalities en- countered in clinical practice (169). Diuretic therapy may lead to hypokalemia. Supple- mental potassium administration must be watched carefully to avoid severe hyperkalemia. One of the safest ways to minimize hypokalemia is to insure adequate dietary intake of potassium. There are no established recommended dietary allowance levels for potassium.

Commercial forms of potassium include (170): Potassium chloride (CAS: 7447-40-7). A colorless, elongated, prismatic or cubical

crystal or a white granular powder. It is odorless, has a saline taste, and is stable in air. Potassium chloride containing anticaking free-flowing, or conditioning

Potassium gluconate: anhydrous (CAS: 299-27-4) and monohydrate (CAS: 35398- 15-3). This is an odorless and slightly bitter tasting white or yellowish white, crystalline powder or granules. It is freely soluble in water and in glycerin, slightly soluble in alcohol and insoluble in ether.

Potassium glycerophosphate (CAS: 1319-70-6). This is a pale yellow, syrupy liquid containing three molecules of water of hydration. It may be prepared as a colorless to pale yellow, syrupy solution having a concentration of 50 to 75%.

Potassium iodide (CAS: 7681-11-0). These hexahedral crystals are either transparent and colorless or somewhat opaque and white or a white, granular powder. It is stable in dry air and slightly hygroscopic in moist air.

Both atomic absorption spectrometry and inductively coupled plasma spectroscopy are used to determine potassium in foods (171). Activation analysis without chemical separation was found to be unreliable for determining potassium (172).

Sodium is the major cation of extracellular fluid. As an electrolyte, sodium helps regulate the movement of body fluids in and out of body cells. Sodium also helps muscles relax and helps transmit nerve impulses. Substantial amounts of sodium can be found in bile and pancreatic juices. The skeleton holds 35 to 40% of total body sodium, however this sodium is unexchangeable with sodium in body fluids.

The most common form of sodium is sodium chloride or table salt. Processed foods are high in sodium and only a small amount of sodium occurs naturally in foods. There is no Recommended Dietary Allowance for sodium. For healthy adults, a minimum of 500 mg daily is considered safe and adequate. The Daily Value used in food labeling was set at ⬍2400 mg sodium by the Nutrition Labeling and Education Act of 1994 (174).

In the 1960s sodium restriction began to gain acceptance as a dietary practice to reduce hypertension (175). Studies have indicated that it is not just the sodium intake but may also be confounding factors ingested with sodium that impact blood pressure (176). Diets low in potassium or calcium were found to amplify the effect of high sodium chloride intake on blood pressure. Weinberger (177) found that there is increasing evidence to support the contention that blood pressure is responsive to sodium intake in susceptible healthy individuals and those individuals with hypertension. Advocating modest sodium restriction to those individuals who are likely to be salt sensitive would be advantageous.

Commercial forms of sodium as a nutrient include (170): Sodium ascorbate (CAS: 134-03-2). A white to yellowish crystalline powder.

Sodium chloride (CAS: 7647-14-5). Generically known as salt. Available in various forms: evaporated salt, rock salt, solar salt, or simply salt. It is transparent to opaque, white crystalline solid of variable particle size. Under humidity of less than 75%, it remains dry but will become deliquescent at higher humidities.

Sodium citrate (CAS: 68-04-2). These colorless crystals or white, crystalline powder are used as the nutrient for cultured buttermilk. Sodium ferric pyrophosphate (CAS: 1332-96-3). This is a white to tan, odorless powder that is insoluble in water but is soluble in hydrochloric acid. Sodium gluconate (CAS: 527-07-1). This granular to fine, crystalline powder is white to tan in color. It is soluble in water, sparingly soluble in alcohol, and insoluble in ether.

Sodium phosphate, dibasic (CAS: 7558-79-4). This is anhydrous or contains two molecules of water of hydration. The white, crystalline powder or granules are

Sodium phosphate, monobasic (CAS: 7558-80-7). This occurs in two forms. The anhydrous form is a white, crystalline powder or granules. The hydrated form of one or two molecules of water is white or transparent crystals or granules. Both are odorless and slightly hygroscopic.

Sodium phosphate, tribasic (CAS: 7601-54-9). This occurs as a white odorless crys- tal or granule or crystalline powder. Sodium pyrophosphate (CAS: 7722-88-5). This white, crystalline, or granular pow- der is anhydrous or contains 10 molecules of water. It is soluble in water and insoluble in alcohol. The form containing ten molecules of water will effloresce slightly in dry air.

Atomic absorption spectrometry and inductively coupled plasma spectroscopy are used to determine sodium in foods. Flame photometry will also give high results for so- dium.

Chloride is the principal anion of extracellular fluids and is widely distributed in the body. Both chloride and sodium amounts and concentrations are responsible for regula- tion of extracellular fluids (178). Chloride functions as a regulator of fluids in and out of body cells and as a helper in transmission of nerve impulses. Stomach acid contains chlo- ride which aids in the digestion of foods and absorption of nutrients. Chloride is found mostly in salt made of sodium and chloride. Small amounts of chloride are found in water supplies.

Excessive chloride, like excessive sodium, may play a role in high blood pressure. For those individuals who are sensitive, dietary intake should be monitored. Deficiencies in chloride are rare in healthy adults. Body cells are made up of various ion channels that allow the transmitting of electrolytes back and forth across cell membranes. In cystic fibrosis, the cystic fibrosis transmembrane conductance regulator is mutated and causes

a disorder in chloride ion transport (179). Children with cystic fibrosis were found to have chloride deficiencies and metabolic alkalosis. Infants that display unexplained hypo- chloraemic metabolic alkalosis should have serum electrolyte balances regularly checked (180).

There are no Recommended Dietary Allowances for chloride. Chloride is commercially available in combination with other minerals as the follow-

ing forms: calcium pantothenate, calcium chloride double salt (CAS: 6363-38-8), choline chloride (CAS: 67-48-1), manganese chloride (CAS: 7773-01-5), potassium chloride (CAS: 7447-40-7), and sodium chloride (CAS: 7647-14-5). Chloride in foods can be ana- lyzed by either a gravimetric method or a volumetric method (181).

E. Iron

Iron is important as a carrier of oxygen in the hemoglobin of red blood cells. Hemoglobin takes oxygen to body cells where it is used for energy production. The resulting byproduct of energy production, carbon dioxide, is removed by hemoglobin. Iron can exist in differ- ent ionic states and therefore can serve as a cofactor to enzymes involved in oxidation– reduction reactions. As energy production proceeds, iron gets recycled protecting against iron deficiency. Iron is also important for its roles in protecting from infections, in con- verting beta carotene to vitamin A, in helping produce collagen, and in helping make body proteins.

Iron is widely available in foods from a variety of sources, both animal and plant.

both heme and nonheme iron in a ratio of about 40 to 60. Heme iron is more rapidly absorbed in the body then nonheme iron. Absorption of nonheme iron can be increased with consumption of vitamin C sources.

Hinderances to nonheme iron absorption can be caused by oxalic acid in spinach and chocolate, phytic acid in wheat bran and legumes, tannins in tea, and polyphenols in coffee (182). These food substances should be limited when trying to absorb iron from plant sources. Recommended Dietary Allowances for males ages 11 to 18 is 12 mg, and for males 19 and older is 10 mg. For females 11 to 50 years old the recommended amount is 15 mg. Over 50 the amount drops to 10 mg largely due to the postmenopausal status of women at this age. Pregnancy raises the recommended amount to 30 mg, and with lactation it is raised to 15 mg (183). Iron is needed most during periods of rapid growth and for women during childbearing years and pregnancy. Prior to menopause, iron is needed to replace that lost from menstrual flow.

Despite its wide availability, iron deficiency is one of the most common nutritional deficiencies, especially among children and women during childbearing years. Deficien- cies can be caused by injury, hemorrhage, or illness and can be aggravated by poorly balanced diet containing insufficient iron, protein, folate, vitamin B12, vitamin B6, and vitamin C (184). Anemia occurs as a result of iron deficiency and symptoms include fatigue, weakness, and general poor health.

Excessive iron overload may be caused by hereditary hemochromatosis or transfu- sion overload. Iron toxicity or poisoning is a short-term disorder that occurs following ingestion of large doses of therapeutic iron. Iron toxicity can lead to severe organ damage and death within hours or days. This is a concern particularly where women in a household are taking iron supplements and children accidently consume large doses of these supple- ments (185).

Commercial forms of iron include (186): Ferric ammonium citrate, brown (no CAS). This is a complex salt of undetermined

structure, composed of iron, ammonia, and citric acid. It occurs as thin, transparent brown, reddish brown, or garnet red scales or granules or as a brownish yellow powder.

Ferric ammonium citrate, green (no CAS). As with the preceding, this complex salt contains the same undetermined structure but occurs as thin transparent green scales, as granules, as a powder, or as transparent green crystals.

Ferric phosphate (CAS: 10045-86-0). This occurs as an odorless, yellowish white to buff colored powder. It contains from one to four molecules of water of hydration. Ferric pyrophosphate (CAS: 10058-44-3). This tan to yellowish white, odorless pow- der is insoluble in water but soluble in mineral acids. Ferrous fumarate (CAS: 141-01-5). This is an odorless, reddish orange to red-brown powder that may contain small lumps. When crushed these lumps may produce

a yellow streak. Ferrous gluconate (CAS: 299-29-6). This powder or granule may have a slight odor, like that of burned sugar. The powder or granules are fine, yellowish gray or pale greenish yellow.

Ferrous lactate (CAS: 5905-52-2). This greenish white powder or crystal has a dis- tinctive odor. It is sparingly soluble in water and practically insoluble in ethanol. Ferrous sulfate (CAS: 7720-78-7). This is odorless but has a saline styptic taste and

Ferrous sulfate, dried (no CAS). This is a grayish white to buff colored powder that dissolves slowly in water and is insoluble in alcohol. Iron, carbonyl (CAS: 37220-42-1). This is an elemental iron produced by the decom- position of iron pentacarbonyl as a dark gray powder. Iron, electrolytic (no CAS). This is an elemental iron produced by electrodeposition in the form of an amorphous, lusterless, grayish black powder. Iron, reduced (no CAS). This is produced by a chemical process and is in the form of a grayish black powder. It is lusterless or has not more than a slight luster.

Near-infrared spectroscopic analysis has been used to determine heme and nonheme iron in raw muscle meats. This diffuse reflectance method is a rapid and simple method. Other methods for analysis of iron in foods include inductively coupled argon plasma atomic emission spectrophotometry, Schricker procedure, and Suzuki procedures (187).

F. Zinc

Zinc is second only to iron in its abundance. Zinc assists in the promotion of cell reproduc- tion, tissue growth, and tissue repair. Over 70 enzymes have zinc as a part of them. Zinc is an essential nutrient for normal wound healing (188). Zinc supplementation was found to improve cell-mediated immune response in older populations (189). Zinc is also in- volved in reactions to either synthesize or degrade major metabolities such as carbohy- drates, lipids, proteins, and nucleic acid. Debate continues regarding the role zinc plays with the common cold. Studies have gone both ways, some showing benefits in using zinc gluconate lozenges and other studies showing no benefits. Mossad et al. (190) found that in the doses and form they used, zinc gluconate significantly reduced the duration of the symptoms of the common cold. On the other hand, Macknin et al. (191) found that zinc gluconate lozenges were not effective in treating cold symptoms of children and adolescents. Zinc gluconate does have an unpleasant taste and nausea is a possible adverse effect (192).

Zinc is primarily found in meat, fish, poultry, milk, and milk products. Whole grain products, wheat germ, black-eyed peas, and fermented soybean paste (miso) are also good sources of zinc.

Recommended Dietary Allowances for males 11 years and older is 15 mg, and for females 11 years and older is 12 mg. Zinc requirements are higher for pregnant and lactat- ing women (193).

Deficiencies in zinc can cause retarded growth, loss of appetite, skin changes, and reduced resistance to infections. During pregnancy, zinc deficiencies can cause birth de- fects (194). High calcium diets have been found to significantly reduce zinc absorption and zinc balance in postmenopausal women (195). Although the interaction between cal- cium and zinc is not completely understood, those individuals with low calcium levels may also have low zinc levels. Zinc toxicity, although rare, can cause deficiency in copper. Toxic levels can also be harmful to the immune system. Because of conflicting studies and the careful balance of zinc levels, a well-balanced diet including foods rich in zinc and other nutrients should be promoted.

Commercial forms include zinc gluconate, zinc oxide, and zinc sulfate: Zinc gluconate (CAS: 4468-02-4). A white or nearly white, granular or crystalline

powder. Depending on the method of isolation, zinc gluconate can occur as a

Zinc oxide (CAS: 1314-13-2). A fine, white, odorless, amorphous powder. Zinc oxide will gradually absorb carbon dioxide from the air. Zinc sulfate (CAS: 7733-02-2). A colorless, transparent prisms or small needles or granular crystalline powder. It is insoluble in alcohol and its solutions are acid to litmus.

All three commercial forms of zinc should be stored in well-closed containers (196). Using atomic absorption with a flame mode is found to be efficient and accurate in

determination of zinc in foods. This method yielded low interlaboratory coefficients of variation and good recoveries (197).

G. Copper

Copper is involved as a part of many enzymes and helps the body to produce energy in cells. Copper also helps make hemoglobin and is needed to carry oxygen in red blood cells. Studies have found that copper is required for infant growth, host defense mecha- nisms, bone strength, red and white cell maturation, iron transport, cholesterol and glucose metabolism, myocardial contractility, and brain development (198).

Sources of copper in food are highly variable. Rich sources include organ meats, oysters, seafood, nuts, chocolate, and seeds. Milk is a poor source of copper although human breast milk has a higher content than cow milk. Concentration of copper in breast milk does decrease with the time of lactation. Most infant formulas are fortified with copper (199). Drinking water will also have a variable amount of copper depending on the natural mineral content and pH of the water and the plumbing system.

Deficiencies of copper can result from decreased copper stores at birth, inadequate dietary copper intake, poor absorption, elevated requirements induced by rapid growth, or increased copper losses. Clinical manifestations of copper deficiency are anemia, neu- tropenia, and bone abnormalities. Copper competes with zinc and iron, therefore high intakes of zinc and/or iron may predispose one to copper deficiency (200). Menkes’ kinky hair syndrome is an inherited disorder affecting normal absorption of copper from the intestine and is characterized by growth of sparse, kinky hair (201).

Overt toxicity from dietary copper sources is rare. Wilson’s disease is a rare inherited disease which causes copper to be accumulated slowly in the liver and then released and taken in by other parts of the body.

Although there are no established Recommended Dietary Allowance levels for cop- per, an estimated safe and adequate daily dietary intake (ESADDI) has been established. The ESADDI level for adults is 1.5 to 3 mg/day (202).

Commercial forms of copper include (203): Copper gluconate (CAS: 527-09-3). This is a fine, light blue powder that is soluble

in water and is slightly soluble in alcohol. Copper sulfate (CAS: 7758-98-7). The blue crystals, crystalline granules or powder function as a nutrient supplement. This chemical will effloresce slowly in dry air.

Atomic absorption in the flame mode can be used efficiently, accurately, with low interlaboratory cooefficients of variation and will provide good results regarding copper content in foods (204).

H. Iodine

Iodine functions as a part of the thyroid hormone, thyroxin. The thyroid regulates the rate that one’s body uses energy. It is involved in the regulation of metabolic activities of cells, especially of the brain during fetal and early postnatal life. When requirements are not met, functional and developmental abnormalities can occur. During 1994, it was esti- mated that some 1.5 billion people in 118 countries were at risk for iodine deficiency, making iodine deficiency one of the world’s single most important causes of preventable brain damage and mental retardation (205). In a study of severely iodine deficient (SID) and mildly iodine deficient (MID) male children, the SID children were found to be slower learners than MID children. Also, the rate of improvement in performances was signifi- cantly different between the two groups. The SID children were poorly motivated to achieve. Iodine deficiency was found to lead to a range of deficits and reflected develop- mental disadvantages of the entire community. These iodine deficient areas do not provide children with the necessary supportive sociopsychological environments for learning new skills and various cognitive abilities (206).

Iodine found in foods is rapidly absorbed as iodide. Iodized salt is the main source of this element. Iodine in milk is influenced by the source of animal feed and the sanitizing solutions used in the dairy industry (207). Drinking water from water purification systems used by Peace Corps volunteers in Niger was found to be a possible source of excessive iodine intake (208). Other sources of iodine include saltwater fish, potatoes, spinach, and almonds (209).

Deficiencies of iodine can occur at all stages of development. During pregnancy, infancy, or early childhood, deficiency may lead to endemic cretinism in an infant or child. Cretinism is not reversible. Goiters, the more commonly known iodine deficiency symptom, can be reversed by providing adequate iodine intake.

Iodine can also be toxic. Goiters, thyroiditis, hypothyroidism, and hyperthyroidism may result from excessive iodine in individuals who are salt sensitive, have other thyroid disorders, or have normally low intacts of iodine. Graves’ disease is the most common form of hyperthyroidism. Calcium and vitamin D losses may occur in cases of hyperthy- roidism, and supplementation with a multivitamin is recommended (210).

The iodine recommended allowance for adults is 150 µg/day. During pregnancy, an additional 25 µg/day is recommended due to the demands of the fetus. An additional

50 µg/day is recommended for lactating women (211). Iodine is available commercially in combination with potassium as potassium iodide. Kelp, a dehydrated seaweed, may be chopped as coarse particles and/or ground for fine powder and provides a salty characteris- tic taste. Kelp is used as a source of iodine (212).

Reliable determination of iodide in foods is difficult. This difficulty is due to the low levels of iodide in foods and the losses of iodide that occur in sample digestion. In capillary electrophoresis analysis, one can simultaneously determine fluoride, chloride, bromide, iodide, and some oxy-halogenated species with indirect UV detection (213).

I. Manganese

Manganese functions as a part of several enzymes. Besides magnesium, manganese can also activate numerous enzymes. Manganese is associated with the formation of connec- tive and bony tissues, growth and reproduction, and carbohydrate and lipid metabolism (214).

Sources of manganese include nuts, seeds, tea, and whole grains. Small amounts are found in meats, dairy products, and sugary and refined foods. Various dietary components influence the bioavailability of manganese and its absorption, retention, and excretion. These components include iron, phosphorus, phytates, and fiber and also may include calcium, copper, and polyphenolic compounds (215).

Manganese deficiency symptoms include poor reproductive performance, growth retardation, congenital malformations in offspring, abnormal formation of bone and carti- lage, and impaired glucose tolerance (216). However, due to homeostatic mechanisms limiting the absorption of manganese from the GI tract, there have been no reported cases of deficiency in humans (217).

The lungs and brain are the primary targets for overexposure to manganese. Fell et al. (218) found cholestatic disease and nervous system disorders associated with high blood concentrations of manganese in patients receiving long-term parenteral nutrition. Manganese madness was first used to describe an initial psychiatric syndrome which in- cluded compulsive behavior, emotional lability, and hallucinations that occurred due to the lungs and gastrointestinal tract absorbing too much manganese oxide (217).

No RDA exists for manganese. However, the estimated safe and adequate daily dietary intake for adults is 2.0 to 5.0 mg/day (216). Commercial forms of manganese include (219):

Manganese chloride (CAS: 7773-01-5). This is available as large, irregular, pink, translucent crystals. Very soluble in hot water and freely soluble in room tempera- ture water.

Manganese gluconate (CAS: 6485-39-8). This is available in either dihydrate or anhydrous form. It is a slightly pink colored powder. Manganese glycerophosphate (CAS: 1320-46-3). Odorless and nearly tasteless white or pinkish white powder. Manganese hypophosphite (CAS: 10043-84-2). Odorless and nearly tasteless, pink,

granular or crystalline powder. It is stable in air and soluble in alcohol. Manganese sulfate (CAS: 7785-87-7). This is a pale pink, granular, odorless powder. Manganese citrate (CAS: 10024-66-5). This is a light pink or pink-white fine, granu-

lar solid. Atomic spectroscopy and neutron activation analysis are two methods believed to

have the most sensitivity and greatest potential for accurately measuring manganese (220).