Trace Minerals
Nutrient | Principal Sources | Functions | Some Effects of Deficiency and Toxicity |
|---|---|---|---|
Liver, processed meats, whole-grain cereals, nuts | Promotion of glucose tolerance | Deficiency: Possibly impaired glucose tolerance Toxicity: | |
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; can be present in Menkes (kinky-hair) syndrome Toxicity: | |
Fluorine | 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 (T4) and triiodothyronine (T3) synthesis, development of fetus | Deficiency: Simple (colloid, endemic) goiter, congenital hypothyroidism with deaf-mutism, impaired fetal growth and brain development (cretinism) 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: Cirrhosis, diabetes mellitus, skin pigmentation; can be present in hemochromatosis |
Whole-grain cereals, pineapple, nuts, tea, beans, tomatoes | Healthy bone structure | 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 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: Red blood cell microcytosis, neutropenia, impaired immunity |