Micronutrients include vitamins and trace elements. By definition, a trace element is <0.01% of the body weight. Trace elements have a variety of essential functions.
| ELEMENT | PHYSIOLOGY | EFFECTS OF DEFICIENCY | EFFECTS OF EXCESS | DIETARY SOURCES |
|---|---|---|---|---|
| Chromium | Potentiates the action of insulin | Impaired glucose tolerance, peripheral neuropathy and encephalopathy | Unknown | Meat, brewer's yeast |
| Copper | Absorbed via specific intestinal transporter; circulates bound to ceruloplasmin; enzyme cofactor (superoxide dismutase, cytochrome oxidase, and enzymes involved in iron metabolism and connective tissue formation) | Microytic anemia, osteoporosis, neutropenia, neurologic symptoms, depigmentation of hair and skin | Acute:nausea, emesis, abdominal pain, coma, and hepatic necrosis; chronic toxicity (liver and brain injury) occurs in Wilson disease and another genetic disorder and secondary to excess intake | Oysters, nuts, liver, margarine, legumes, corn oil |
| Fluoride | Incorporated into bone | Dental caries | Chronic:dental fluorosis water | Toothpaste, fluoridated water |
| Iodine | Component of thyroid hormone | Hypothyroidism | Hypothyroidism and goiter; maternal excess may cause congenital hypothyroidism and goiter | Saltwater fish, iodized salt |
| Iron | Component of hemoglobin, myoglobin, cytochromes, and other enzymes | Anemia, decreased alertness, impaired learning | Acute: nausea, vomiting, diarrhea, abdominal pain, and hypotension; chronic excess usually secondary to hereditary disorders; causes organ dysfunction | Deficiency may also result from blood loss (hookworm infestation, menorrhagia) |
| Manganese | Enzyme cofactor | Hypercholesterolemia, weight loss, decreased clotting proteins | Neurologic manifestations, cholestatic jaundice | Nuts, grains, tea |
| Molybdenum | Enzyme cofactor (xanthine oxidase and others) | Tachycardia, tachypnea, night blindness, irritability, coma | Hyperuricemia and increased risk of gout | Legumes, grains, liver |
| Selenium | Enzyme cofactor (prevents oxidative damage) | Cardiomyopathy (Keshan disease), myopathy | Nausea, diarrhea, neurologic manifestations, nail and hair changes, garlic odor | Meat, seafood, whole grains, garlic |
| Zinc | Enzyme cofactor; constituent of zinc finger proteins, which regulate gene transcription | Decreased growth, dermatitis of extremities and around orifices, impaired immunity, poor wound healing, hypogonadism, diarrhea; supplements beneficial in diarrhea and improve neurodevelopmental outcomes | Abdominal pain, diarrhea, vomiting; may worsen copper deficiency | Meat, shellfish, whole grains, legumes |
Reference:
Nelson Textbook of Pediatrics 18th Edition