Trace Elements in Human Nutrition

Iron
Is a constituent of haemoglobin, myoglobin and enzymes. Associated with ferritin, hemosiderin ( spleen, liver, bone marrow) and transferrin ( blood). Source is meat, eggs, vegetables, cereals. Deficiency is observed in four stages in life 1) At 6mnts‐4yrs iron content of milk is low, body grows rapidly and body reserves are insufficient 2) during early adolescence due to expanding RBC mass and need to deposit iron in myoglobin 3) menstrual iron loss 4) pregnancy, expanding blood volume of mother, demands of fetus and placenta, blood loss during childbirth. Manifests as anemia, impair psychomotor development, decreased physical activity and resistance to fatigue.Excess is never encountered from food, rarely due to long term ingestion of home brews made in iron vessels or children ingesting medicinal iron supplements. Idiopathic hemochromatosis‐inborn error of metabolism – enhanced iron absorption

Iodine
Is a component of thyroid hormones. Source is from seafood, in czech republic also eggs, milk and iodised salt ( 25mg/kg). Deficiency manifests as creatinism, goitre, stillbirth, mental retardation, mutism.

Copper
Is a constituent of many enzymes, participating in iron binding in Hb ( hematopoiesis), formation of pigmentation, immune function, constituent of cellular respiratory enzymes. Source‐ organ meats (liver), egg whites, seafood, nuts and seeds. Deficiency‐exceptional, described in malnourished children‐ anemia, bone demineralisation, impaired immunity, hair and nail growth

Chromium
Trivalent form potentiates action of insulin‐increased glucose tolerance, six valent form is allergen and carcinogen. Source‐yeast, meat, cheese, nuts. Deficiency‐decreased glucose tolerance, hyperlipidemia, acceleration of atherosclerotic changes

Fluoride
Bone and teeth formation. Source‐water, tea, fish if consumed with bone. Deficiency‐ increased caries formation, poor bone mineralisation. Excess‐brown pigmentation of teeth

Selenium
Present at active site of glutathione peroxidise that catalyses the breakdown of hydroperoxides, thus preventing damaged caused by free radicals. Positively influences immunity, probably anti carcinogenic. Souce‐seafood, kidney, liver ( grains and seeds depending on soil). Deficiency‐decreased lymphocytes and natural killer activity, decreased interferon formation, keshan disease ( cardiomyopathy), kashin – beck disease (osteoarthropathy)

Zinc
Involved in >200 enzyme reactions, component of superoxide dismutase, preventing oxidative stress, positively influence tissue growth and healing, participates in insulin formation and spermatogenesis. Source‐meat, liver, eggs, seafood. Deficiency – growth retardation, decrease immunity, loss of appetite, skin, nail, hair changes.

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 * 1) Minerals in Human Nutrition