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Overview of Minerals

by Larry E. Johnson, MD, PhD

Six macrominerals are required by people in gram amounts.

  • Four cations: Na, K, Ca, and Mg

  • Two accompanying anions: Cl and P

Daily requirements range from 0.3 to 2.0 g. Bone, muscle, heart, and brain function depend on these minerals.

Nine trace minerals (microminerals) are required by people in minute amounts:

  • Chromium

  • Copper

  • Iodine

  • Iron

  • Fluorine

  • Manganese

  • Molybdenum

  • Selenium

  • Zinc

Dietary guidelines for trace minerals have been determined. All trace minerals are toxic at high levels; some minerals (arsenic, nickel, and chromium) may be carcinogens.

Mineral deficiencies (except of iodine, iron, and zinc) do not often develop spontaneously in adults on ordinary diets; infants are more vulnerable because their growth is rapid and intake varies. Trace mineral imbalances can result from hereditary disorders (eg, hemochromatosis, Wilson disease), kidney dialysis, parenteral nutrition, or restrictive diets prescribed for people with inborn errors of metabolism.

Trace Minerals

Nutrient

Principal Sources

Functions

Effects of Deficiency and Toxicity

Chromium

Liver, processed meats, whole-grain cereals, nuts

Promotion of glucose tolerance

Deficiency: Possibly impaired glucose tolerance

Copper

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

Enzyme component, hematopoiesis, bone formation

Deficiency: Anemia in undernourished children, Menkes (kinky-hair) syndrome

Toxicity: Wilson disease, copper poisoning

Fluorine

Seafood, tea, fluoridated water (sodium fluoride 1.0–2.0 ppm)

Bone and tooth formation

Deficiency: Predisposition to dental caries, possibly osteoporosis

Toxicity: Fluorosis, mottling and pitting of permanent teeth, exostoses of spine

Iodine

Seafood, iodized salt, eggs, cheese, drinking water (content varies)

Thyroxine (T 4 ) and triiodothyronine (T 3 ) synthesis, development of fetus

Deficiency: Simple (colloid, endemic) goiter, cretinism, deaf-mutism, impaired fetal growth and brain development

Toxicity: Hyperthyroidism or hypothyroidism

Iron

Many foods (except dairy products)—soybean flour, beef, kidney, liver, fish, poultry, beans, clams, molasses, enriched grains and cereals (bioavailability variable in plant sources)

Hemoglobin and myoglobin formation, cytochrome enzymes, iron-sulfur proteins

Deficiency: Anemia, pica, glossitis, angular cheilosis

Toxicity: Hemochromatosis, cirrhosis, diabetes mellitus, skin pigmentation

Manganese

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

Healthy bone structure

Component of manganese-specific enzymes: glycosyltransferases, phosphoenolpyruvate carboxykinase, manganese-superoxide dismutase

Deficiency: Questionable

Toxicity: Neurologic symptoms resembling those of parkinsonism or Wilson disease

Molybdenum

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

Component of coenzyme for sulfite oxidase, xanthine dehydrogenase, and one aldehyde oxidase

Deficiency: Tachycardia, headache, nausea, obtundation (sulfite toxicity)

Selenium

Meats, seafood, nuts, plant-based foods (selenium content varying with soil concentration)

Component of glutathione peroxidase and thyroid hormone iodinase

Deficiency: Keshan disease (viral cardiomyopathy), muscle weakness

Toxicity: Hair loss, abnormal nails, nausea, dermatitis, peripheral neuropathy

Zinc

Meat, liver, oysters, seafood, fortified cereals, peanuts, whole grains (bioavailability variable in plant sources)

Enzyme component, skin integrity, wound healing, growth

Deficiency: Impaired growth and delayed sexual maturation, hypogonadism, hypogeusia

Toxicity: RBC microcytosis, neutropenia, impaired immunity

Guidelines for Daily Intake of Minerals

Category

Age (yr) or Time Frame

Chromium (mcg)

Copper (mcg)

Fluoride (mg)

Iodine (mcg)

Iron (mg)

Manganese (mg)

Molybdenum (mcg)

Selenium (mcg)

Zinc (mg)

Recommended daily intake

Infants

0.0–0.6

0.2

200

NR

110

0.27

0.3

2

15

2

0.7–1.0

5.5

220

0.01–0.5

130

11

0.6

3

20

3

Children

1–3

11

340

0.7

90

7

1.2

17

20

3

4–8

15

440

1

90

10

1.5

22

30

5

Males

9–13

25

700

2

120

8

1.9

34

40

8

14–18

35

890

3

150

11

2.2

43

55

11

19–30

35

900

4

150

8

2.3

45

55

11

31–50

35

900

4

150

8

2.3

45

55

11

51+

30

900

4

150

8

2.3

45

55

11

Females

9–13

21

700

2

120

8

1.6

34

40

8

14–18

24

890

3

150

15

1.6

43

55

9

19–30

25

900

3

150

18

1.8

45

55

8

31–50

25

900

3

150

18

1.8

45

55

8

51+

20

900

3

150

8

1.8

45

55

8

Pregnant

30

1000

3

220

27

2.0

50

60

11

Breastfeeding

45

1300

3

290

9

2.6

50

70

12

Upper limit (UL)

Infants

< 1

ND

ND

0.7–0.9

ND

40

ND

ND

45–60

4–5

Children

1–8

ND

1000–3000

1.3–2.2

200–300

40

2–3

300–600

90–150

7–12

People

9

ND

5,000–10,000

10

600–1100

40–45

6–11

1100–2000

280–400

23–40

N ote: Recommended dietary allowances (RDAs) are shown in regular type. RDAs are set to meet the needs of 97 to 98% of people in a group.

Adequate intakes (AIs) are shown in bold type. For healthy breastfed infants, AIs are the mean intake. For other groups, AIs are amounts believed to meet the needs of all people in the group, but because of lack of data, the percentage of people covered cannot be specified with confidence.

NR = not recommended; ND = not determinable because of lack of data, so sources of intake should be limited to foods.

Adapted from Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc, Food and Nutrition Board, Institute of Medicine. Washington, DC, National Academies Press, 2002, p. 772–773.

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