Trace element

Function

Dietary sources

Causes deficiency

Risk groups

Clinical findings

Screening and management

Chromium

Metabolism of fats and carbohydrates

Muscle meat, grain, legumes, nuts

Restricted food access

Extremely rare,
PN

Impaired glucose tolerance, weight loss, confusion, peripheral neuropathy

Levels more commonly checked for excess (e.g. in PN dependent patients), ubiquitous in food, no dosing needed

Copper

Mineral cofactor superoxide dismutase, enzymes related to electron transfer, iron oxidation, melanin formation and connective tissue synthesis

Organ and muscle meat, nuts, cereals,

Long term PN without Cu added

Extremely rare,
PN

Impaired glucose tolerance, weight loss, confusion, peripheral neuropathy, anaemia, neutropenia

Malnutrition, PN dependent patients

Iodine

Component of thyroid hormones required for normal growth and development

Sea fish, seaweed, iodised salt, dairy (through cattle supplementation)

Environmental deficiency in inland Africa and Asia, Sth America, mountainous areas
WHO map iodine
Absorbed stomach and upper SI

Environmental deficiency in inland Africa and Asia
Goitrogens can impair binding of I to thyroglobulin (brassicas, sweet potato, maize)

Hypothyroidism (lethargy, poor cold tolerance, bradycardia, goitre), cretinism (intellectual disability (reduced language and memory skills), deaf-mutism, +/- hypothyroidism, short stature), miscarriage, stillbirth, increased perinatal mortality.

24 hr urine iodine excretion (90% excreted via kidneys) or random urine iodine:creatinine

Iodised salt
Mx thyroid disease

Iron

Component in heme and cytochrome proteins

Organ and muscle meat, pulses, dried apricots, green leafy vegetables

Restricted food access, increased losses, including parasite infection (inc. hookworm), malaria

Young children, esp those born to deficient mothers, high milk intake, vegetarians,
chronic disease, PN dependent

Microcytic anaemia, pallor, weakness, shortness of breath

See anaemia and iron deficiency guideline

Manganese

Component metalloenzymes, bone formation, metabolism protein, carbohydrate, colesterol

Cereals, tea, vegetables, low ferritin levels increase absorption, low bile excretion reduces excretion

Clinical deficiency not usually seen, even with low dietary intake if otherwise healthy.

Extremely rare

Impaired growth, reproductive function and glucose tolerance

Levels more commonly checked for excess (e.g. in PN dependent patients) See NRV

Molybdenum

Enzyme cofactor, including for purines/pyridines

Legumes, grains, nuts

Clinical deficiency not usually seen, reported in long term PN without Mb added.

Extremely rare
PN

Neurological impairment in genetic abnormality sulphite oxidase

Levels not usually checked
See NRV

Selenium

Antioxidant, redox reactions, thyroid metabolism (conversion T4 to T3), glutathione peroxidase

Seafood, chicken, muscle meat, fish, brazil nuts, eggs. Cereals and plant food content reflect soil content

Areas where soil levels low, gut disease

Seen in parts of China, Finland (soil content low)

Cardiomyopathy (Keshan disease, affects mostly children and women), myositis and nail dystrophy

Screen if malnutrition, PN dependent, See NRV

Zinc

Cofactor for many enzymes, inc ALP, RNA/DNA polymerase and superoxide dismutase

Seafood, organ and muscle meat, grains, milk, eggs. Higher bioavailability from animal sources than plant foods

Restricted food access, increased losses

Restricted food access, any cause of chronic diarrhoea, chronic illness

Acrodermatitis enteropathica, delayed wound healing, impaired taste, growth failure, delayed puberty and diarrhoea

Screen if malnutrition, diarrhoea, PN dependent, features deficiency Zinc dosing