A number of minerals have been shown to be essential ill animals and an increasing number of deficiency syndromes are becoming recognized in humans. Longterm total parenteral nutrition allowed trace-element deficiency to be studied in controlled conditions; now trace elements are always added to long-term parenteral nutrition regimens. It is highly probable (but difficult to study because of multiple deficiencies) that trace-element deficiency is also an important accompaniment of all PEM states. Sodium, potassium, magnesium and chloride.
The daily RNI for men is 160 urnol (8.7 mg) and for women 260 urnol (14.8 mg). Iron deficiency is common worldwide, affecting both developing and developed countries alike. It is particularly prevalent in women of a reproductive age. Dietary iron overload is seen in the South African Bantu men who cook and brew in iron pots.
The daily RNI is 1.2 mg (19 urnol).
Menkes’ kinky hair syndrome is a rare condition due to malabsorption of copper. Infants with this sex-linked abnormality develop growth failure, mental retardation, bone lesions and brittle hair. Anaemia and neutropenia also occur. This condition, which serves as a model for copper deficiency, supports the idea that some of the clinical features seen in PEM are due to copper deficiency. Breast and cows’ milk are low in copper and supplementation is occasionally necessary when first treating PEM.
Copper toxicity occurs in Wilson’s
The daily RNI is 9 mg (140 urnol). Zinc is involved in many metabolic pathways, often acting as a coenzyme; it is essential for the synthesis of RNA and DNA. It is widely available in food.
Acrodermatitis enteropathica is an inherited disorder due to malabsorption of zinc. Infants develop growth retardation, severe diarrhoea, hair loss and associated Candida and bacterial infection. Zinc supplement results in a complete cure. This condition provides a model for zinc deficiency. Deficiency probably plays a role in PEM.
Zinc levels have also been shown to be low in some patients with malabsorption, skin disease and AIDS, but the exact role of zinc in these situations is disputed. High zinc levels from water stored in galvanized containers interfere with iron and copper metabolism.
The daily RNI is 140 ILgu.i umol). Iodine exists in foods as inorganic iodines which are efficiently absorbed.
Many mountainous areas throughout the world lack iodine in the soil and iodine deficiency is a WHO priority. Endemic goitre occurs in areas where the daily intake is below 70 ILg (p.803) and here 1-5% of babies are born with cretinism. In these areas iodized oil should be given intramuscularly to all reproductive women. In developed countries, salt is iodized and endemic goitre has disappeared
In areas where the level of fluoride is less than 1 p.p.m. in drinking water, dental caries is more prevalent. Fluoridation of the water reduces this. Excessive fluorine intake can result in fluorosis, in which there is infiltration of the enamel of the teeth with fluorine, producing pitting and discoloration.
The daily RNI is 60 ILg (0.8 umol), Keshan disease is a selenium-responsive cardiomyopathy found in areas of China.
The daily RNI is 700 mg (17.5 mmol).
This is found in many foods but particularly in milk. Its absorption from the gastrointestinal tract is vitamin D-dependent. Ninety-nine per cent of body calcium is in the skeleton. Increased calcium is required in pregnancy and lactation, when dietary intake must be increased. Calcium deficiency is usually due to vitamin D deficiency.
The daily RNI is equivalent to calcium, i.e. 17.5 mmol. Phosphates are present in all natural foods and dietary deficiency has not been described. Patients taking large amounts of aluminium hydroxide can, however, develop phosphate deficiency owing to binding in the gut lumen. It can also be seen in total parenteral nutrition. Symptoms include anorexia, weakness and osteoporosis. Other trace elements of possible significance.