This document discusses the trace element iodine. It notes that iodine is essential for normal thyroid function and the production of thyroid hormones. It was discovered in 1811 by a French chemist. Approximately 15-20 mg of iodine is found in the human body, with 70-80% concentrated in the thyroid gland. Iodine deficiency can cause mental and physical disabilities collectively called iodine deficiency disorders. The document outlines dietary sources of iodine and its metabolism and role in the body.

1. Trace element-II
Binaya Tamang
UCMS
Department of Biochemistry

2. Iodine
• Iodine is an imperative micronutrient
• for the normal thyroid function necessary for the
normal growth and development of our brain
and body .
• inevitable micronutrient involved in the
synthesis of thyroid hormones:
• Thyroxine (T4) and Triiodothronine (T3)

3. DISCOVERY
• Iodine was isolated by
French chemist, Courtois,
in 1811,
• who accidentally
discovered iodine as the
violet vapour
• arising from the seaweed
ash
• while manufacturing
gunpowder for
Napoleon’s army.

4. • In our human body,
approximately 15-20 mg of iodine is present,
of which 70-80 % is concentrated in the thyroid
gland
• Approximately 90% of the dietry iodine is
absorbed in the upper small intestine after being
converted into the iodide ion in the gut lumen.
• iodine deficiency may cause a mental and physical
disabilities, collectively called as iodine deficiency
disorders (IDD)

5. Affects all age group
• Iodine deficiency affects the populations of all
age group with
• pregnant woman and children forming most
vulnerable groups.
• Deficiency during childhood reduces somatic
growth, cognitive and motor function

6. • Salt is the food ingredient that is consumed by
the general population on the daily basis. If
fortified with the iodine it is called as Iodized salt
• Mainly, two organs i.e., thyroid gland and kidneys
are responsible for the clearance of iodine from
the plasma

7. Urinary iodine concentration
• For a recent iodine intake,
• the most sensitive marker is urinary iodine
concentration (UIC)
• because 90% of the iodine absorbed by the body
eventually appears in urine
• and therefore, is the index of choice for
evaluating degree of iodine deficiency and its
correction

8. DIETARY SOURCES
• Seafoods, drinking water, vegetables, fruits
(grown on seaboard).
• High altitudes are deficient in iodine content in
water as well as soil.
• Plant and animal foods of these areas, therefore,
contain lesser amount of iodine.
• In these regions, iodine is added to drinking
water or to table salt.

9. Plasma iodine
• 4-10 mg/dl.
• Most of this is present as protein bound iodine
(PBI).
• RBC do not contain iodine.

10. Dietary requirements
• Adults-100-150 μg/day
• Pregnant woman- 200 μg/day

11. METABOLISM OF IODINE
• iodine in our food has reduced to iodide.
• iodide form is taken up in the stomach and
throughout the small intestine via mucous
membrane they finally reach in to the blood
• Iodine is transported into thyroid by sodium iodide
symporter (NIS) against concentration gradient
• The body of a healthy adult contains 15 to 20 mg of
iodine, of which 70 to 80% is in the thyroid
• A transmembrane NIS, transfers iodide into thyroid
tissue at 20 to 50 times higher than in the plasma.

13. Goitrogenic substances
Interferes with the production of thyroid
hormones
• Thiocynates
• Nitrates
• Perchlorates
• Drugs like thiouracil and thiourea
• Certains vegetables like cabbage, cauliflower and
turnip- containg goitrogenic factors ( mostly
thiocynates).

15. Iodine disorders
Hypothyroidism
• Myxoedema
• cretinism
Hyperthyroidism
• Grave’s disease

16. ZINC (Zn)
• Total content of zinc : 2g
• out of which 60% is in skeletal muscles and 30%
in bones.
• Highest concentration of zinc is seen in
hippocampus area of brain and prostatic
secretion.
• RBCs contain Zn ( 1.5 mg/dl) in association with
carbonic anhydrase.

17. dietary sources
• grains, beans, nuts, cheese, meat and shellfish.
• Zinc and copper will competitively inhibit each
other's absorption.
• So, zinc is therapeutically useful to reduce copper
absorption in Wilson's disease

18. Absorption
• Mainly in the duodenum
• Zn absorption appears to be dependent on
transport protein- metallothionein.
• Copper, calcium, cadmium, iron and phytate will
interfere with the absorption of zinc.
• In liver, zinc is stored.
• Zinc is excreted through pancreatic juice and to a
lesser extent through sweat.

19. FUNCTIONS
Essential component of several enzymes e.g.
• Carbonic anhydrase,
• alcohol dehydrogenase
• Alkaline phosphatase
• carboxy peptidase
• superoxide dismutase ( cytosolic)
Antioxidant since, the SOD protects from free
radicals
The storage and secretion of insulin from beta cells
of pancrease require Zn

20. • Zn is require to maintain normal level of vitamin
A in serum. Zn promotes the synthesis of retinol
binding protein.
• It is required for wound healing. Zn enhances cell
growth and division, besides stabilizing
biomembranes.
• Gusten, a zinc containing protein of saliva, is
important for taste sensation

21. • Zn is essential for proper reproduction function.
• Zinc deficiency also lowers spermatogenesis in
males and menstrual cycles are disturbed in
females.
• Prasad et al have shown that zinc deficiency
may lead to ‘dwarfism’ and ‘hypogonadism’.
• In such dwarfs, zinc concentration in plasma, red
blood cells, hair, urine and faeces was found to be
less than control subjects.

22. Clinical aspects
• Acrodermatitis enteropathica: is a rare inherited
metabolic disease of zinc deficiency caused by
defect in the absorption of Zn from the intestine.
• Zinc toxicity is often seen in welders due to
inhalation of zinc oxide fumes.
• Nausea, gastric ulcer, pancreatitis, anemia and
excessive salivation.

23. Deficiency
• growth retardation, poor wound healing, anemia,
loss of appetite, loss of taste sensation
• Neuropsychiatric of chronic alcoholism may be
partly due to Zinc deficiency.

24. Selenium
• In mammals, glutathione peroxidase (GP) is the
important selenium containing enzyme.
• Selenocystein is component.
• RBC contains good quantity of glutathione
peroxidase.
• 21 st amino acid.
• Protects the cell against the damage caused by H2O2.

25. • Thyroxin is converted to T3 by 5'-de-iodinase,
which is a selenium containing enzyme. In Se
deficiency, this enzyme becomes less active,
leading to hypothyroidism.
• Selenium acts as a nonspecific intracellular anti-
oxidant. This action of Se is complementary to
vitamin E.
• In Se deficiency, tissue vitamin E content is
depleted.

26. Keshan disease
• In Keshan province in China, the soil is deficient
in selenium. This leads to prevalence of Keshan
disease.
• It is characterized by multifocal myocardial
necrosis, cardiac arrhythmias and cardiac
enlargement.

27. Selenosis.
• Selenium toxicity is called selenosis.
• Selenium is present in metal polishes and anti-
rust compounds.
• symptoms include hair loss, falling of nails,
diarrhea, weight loss, and garlicky odor in
breath.

28. Thank You