1509, recognized as element
Considered unlikely until 1955
conditioned human deficiency demonstrated in 1956
1961, hypogonadal dwarfism suggested to be zinc
Relatively abundant mineral
Good sources: shellfish, beef and other red meats
Slightly less good: Whole-grains
most in bran and germ portions
80% lost to milling
phytates, hexa & penta phosphates depress absorption
P/Zn ratios of 10 or more
Relatively good sources: nuts and legumes
Eggs, milk, poultry & fish diets lower than
pork, beef, lamb diets
High meat diets enhance absorption
280g or 10 oz fits right into food pyramid guide
cys & met form stable chelate complexes
Zinc absorption is greater from a diet high in
animal protein than a diet rich in plant proteins
. Phytates, which are found in whole grain
breads, cereals, legumes and other products,
can decrease zinc absorption .
Foods contain element zinc, much
of it bound to protein or DNA.
Oysters (> 70 mg per
Meats (2-3 mg/100g).
Shellfish (2.7 mg/100g)
Other good food sources
beans, nuts, certain seafood,
whole grains, fortified
breakfast cereals, and dairy
GIT modulates the quantity of exogenous
dietary zinc absorbed and the quantity of
endogenous zinc excreted
More than 70% of a small zinc dose (less than 3
mg) is absorbed from the small intestine.
Maximum absorption occurs in duodenum
There is sustained release from enterocytes into
portal circulation for ~ 9h
Zinc absorption mainly achieved by 2 families
of zinc transporters;
1. ZIP Family
2. ZnT Family
Routes: intestine, kidneys, integument, and semen
After a meal, maximum zinc secretion occurs through
Maximum reabsorption occurs from mid-jejunum and
Total amount excreted = Amount secreted – Amount
Excretion of endogenous zinc by the intestine depends
on the ‘zinc status’ of the body.
Impaired taste (hypoguesia)
Delayed healing of wounds, burns, decubitus ulcers
Impaired appetite & food intake
Eye lesions including photophobia & lack of dark
dermatitis, alopecia, diarrhea, emotional disorder,
weight loss, infections, hypogonadism in males
growth retardation and delayed puberty in
adolescents, hypogonadism in males, rough skin,
poor appetite, mental lethargy, delayed wound
healing, taste abnormalities and abnormal dark
oligospermia, slight weight loss and
Zn deficient rats failed to conceive
Abnormalities of blastocyst development
Offspring had high incidence of abnormalities
Deformities of brain, skull, limbs, eyes, heart, lungs
Low Zn intake during the third trimester may
not have such profound effects
Main stages of differentiation are already complete
Can result in low birth weight, and prolonged and
Excess accumulation within cells may disrupt
functions of biological molecules
Protein, enzymes, DNA
Leads to toxic consequences
Impaired copper availability
Acute excessive intakes
Local irritant to tissues and membranes
GI distress, nausea, vomiting, abdominal cramps, diarrhea
Sources of exposure – drinking water, feed, polluted air
Genetic disorder of zinc absorption.
Presents during infancy.
Characterized mainly by a triad consisting of
1. Acral dermatitis
In infants bottle fed with bovine milk, days to
week, breast fed infants soon after feeding
In older children its acquired zinc deficiency.
Acrodermatitis enteropathica; autosomal
recessive trait resulting in failure to absorb
Acquired zinc deficiency; secondary to reduced
dietary intake , malabsorption, increased
urinary loss, etc.
Skin mucous membrane and hair are involved.
Lesions are pink and later become brightly
Impaired wound healing.
Irritable with depressed mood
Loss of weight
Sensitivity to light
Red glossy tongue and mouth ulcers
1mg/kg body weight of oral zinc
supplementation per day of life.
Zinc gluconate better tolerated than sulfate.
Dietary or iv supplementation with zinc salts
with two or three times , the RDA restores
normal zinc status in days or week.
All children above 6months should receive a
uniform dose of 20mg elemental zinc as soon as
diarrhoea starts and continue for 14 days.
2 to 6mnths- 10mg/day for 14 days.
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