1
Third stage
Medicine
Lec-5
د
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وائل
1/1/2014
Inorganic nutrients (Minerals)
Deficiency is seen when there is inadequate dietary intake of minerals or excessive loss
from the body. Toxic effects have also been observed from self-medication and disordered
absorption or excretion. Examples of clinical toxicity include excess of iron
(haemochromatosis or haemosiderosis), fluoride (fluorosis), copper (Wilson's disease) and
selenium (selenosis, seen in parts of China).
Calcium:
• calcium is the most abundant cation in the body.
• Circulating ionized calcium is tightly regulated.
• Calcium content in food is usually adequate, but calcium absorption may be impaired
in the following situation:
1. Vitamin D deficiency
2. Malabsorption.
3. Consuming food containing excess of oxalate(e.g. Spinach),or phytate(whole grain
cereals) which form inorganic salts with calcium.
• calcium deficiency impairs bone mineralization .
• High calcium intake may prevent osteoprosis
Phosphorus:
Dietary deficiency of phosphorus is rare (except in older people with limited diets) since it is
present in nearly all foods and phosphates are added to a number of processed foods.
Phosphate deficiency in adults occurs:
1. in patients with renal tubular phosphate loss
2. due to prolonged high dosage of aluminium hydroxide
3. sometimes when alcoholics are fed with high-carbohydrate foods
4. in patients receiving parenteral nutrition if inadequate phosphate is provided.
Deficiency causes hypophosphataemia and muscle weakness secondary to ATP deficiency.
Iron:
The major consequence of iron deficiency is anaemia This is one of the most important
nutritional causes of ill health in all parts of the world. Dietary iron overload is occasionally
observed and results in iron accumulation in the liver and, rarely, cirrhosis.
Haemochromatosis results from an inherited increase in iron absorption.
Iodine:
About a billion people in the world are estimated to have an inadequate iodine intake
and are hence at risk of iodine deficiency disorder.
2
Goitre is the most common manifestation, affecting about 200 million people
In those areas where most women have endemic goitre, 1% or more of babies are
born with cretinism (characterised by mental and physical retardation).
There is a higher than usual prevalence of deafness, slowed reflexes and poor
learning in the remaining population.
The best way of preventing neonatal cretinism is to ensure adequate levels of iodine
during pregnancy. This can be achieved by intramuscular injections with 1-2 mL of
iodised poppy seed oil (475-950 mg iodine) to women of child-bearing age every 3-5
years, by administration of iodised oil orally at 6-monthly or yearly intervals to adults
and children, or by providing iodised salt for cooking.
Zinc:
Acute zinc deficiency has been reported in patients receiving prolonged zinc-free
parenteral nutrition and causes diarrhoea, mental apathy, a moist eczematoid
dermatitis, especially around the mouth, and loss of hair.
Chronic zinc deficiency occurs in dietary deficiency, malabsorption syndromes,
alcoholism and its associated hepatic cirrhosis.
chronic deficiency has been associated with dwarfism and hypogonadism.
Zinc deficiency is thought to be responsible for one-third of the world's population
not reaching their optimal height
Fluoride:
If the local water supply contains more than 1 part per million (ppm) of fluoride, the
incidence of dental caries is low.
Soft waters usually contain no fluoride, whilst very hard waters may contain over 10
ppm.
The benefit of fluoride is greatest when it is taken before the permanent teeth erupt,
while their enamel is being laid down.
The addition of traces of fluoride (at 1 ppm) to public water supplies is now a
widespread practice.
Selenium:
Plants derive selenium from soil ,which varies in its selenium content in different
continents.
Selenium deficiency can cause hypothyroidism, cardiomyopathy in children and
myopathy in adults.
Excess selenium ca.n cause heart disease
Copper:
Copper metabolism is abnormal in Wilson's disease.
Deficiency occasionally occurs but only in young children, causing microcytic
hypochromic anaemia, neutropenia, retarded growth, skeletal rarefaction and
dermatosis.