Iodine

Most of I in the diet comes from seaHigh concentrations in sea water and sea foodPlants grown close to sea are high in II content in inland plants and water depends on I level of soilI comes to food from contaminants and additives. Therefore, dairy products may contain Sterilizing agents and colourings contain IFortified salt contain II in sea salt is lost due to sun drying

I in the bodyEssential component of thy hormonesThy hormones regulate BMR, growth & development and promote protein synthesisRDA for I in men and women 150g /dayNeeds are increased during preg and lactDeficiency reduces production of thy hormones and then metabolic rate slows causing fatigue and weight gain

ImportanceBody contains 15-50mg I, (70-80% in thyroid gland) Functions as an integral part of thyroid hormones (T4 & T3) Thyroid hormones are required for : - normal growth & development of tissues and, - maturation of the whole body - maintaining the metabolic rate through energy production and oxygen consumption of cells

IDDGoiter is the most visible sign of IDDIn pregnancy ID leads to mental and physical defects in the baby ranging from mild to cretinism. ID preg mothers suffer from still births and abortionsIn severely ID mothers the effects on baby are irreversible

ID in adults make persons dull, listless and easy tired, less active and apathy Their productivity is reduced and mental function impairedThere can be reproductive failure

In inadequacy of thyroid hormoneHypothyroidism where basal metabolic rate is reduced, and general activities of the individual is decreased, normal growth & devt impairedWhen T4 falls secretion of TSH from the pituitary is increased. This enhances thyroid activities and out-put of T4 into circulation

Spectrum of abnormalitiesGoiterDelayed milestonesLowered educational performance (low IQ)Speech and hearing defectsRetarded physical developmentMental retardationSquintStunting of limbs in children and adolescents

ContdSkin changesEnlargement of tongueHoarsening of voiceSlowness of movementsRising lipid content of plasmaCardiac insufficiencyFluid retention

Metabolism is closely linked to thyroid functionAbsorbed in the form of iodide and taken up immediately by the thyroid glandConverted to I in the gland and bound to tyrosine residues to form T4 and T3Thyroid gland needs about 60g iodide/day for adequate supply of T4 Excess I is excreted in urine (small amounts in sweat & faeces also)

Absorption of IOrganic form is rapidly degraded in the gut to iodide.Almost completely absorbed in the stomach and upper small bowel.80% thyroxin absorbed remainder lost in fecesIodide used in fortification is readily absorbedIodate is reduced to iodide for absorption

Transport of IAbsorbed iodide appears in the blood in free and dializable form (not bound to any protein)Rapidly picked up by the thyroid and kidneyConcentration in blood depends on supply and clearance rate

StorageOnly storage site is thyroid glandStored as hormone or hormone precursors10-20mg of I in abundant supply< 200g in chronic I deficiency

Turnover of thyroid hormone is slowHalf life of thyroxin (T4) 7 days triidothyronine (T3) 1.5-3 days

Recommended Dietary Intake WHO/UNICEF/ICCIDD (2001)Up to 59months 90 g/day6-12y 120>12y and adults 150Preg and lactating 200

Inhibition by goitrogensCyanogenic glycosides in cassava, maize, bamboo shoots, sweet potatoes, lima beans and millet Release cyanide which forms thiocyanate, this competes with I uptake by the glandGoitrins in cabbage, rape and mustard also converted to thiocyanate, blocks the uptake and inhibits coupling process to produce T4 (increase supply to overcome)

Management of IDDepends on: - the severity of IDD - the accessibility of target population - the resources available

Food based approachesUse of natural foods

Use of iodized salt to provide 120-140g/day of iodineConcentration in salt be: 20-40mg of I /kg of salt20% losses at manufacturing, storage and transport20% losses during cooking Average salt intake is 5-10g/person/dayPotassium iodate or iodide used

Iodination of drinking water- in ChinaFortification of infant formulas concentration of 200g/l in pre-term formula and /or 100g/l in starting formulaFortification of foods for farm animalsUse of iodized oil administered IM or orally in the form of slowly resorbable iodized oil. Effectiveness can be enhanced by use of monounsaturated oil (rapeseed or peanut oil). Deworming is needed as intestinal parasites suck oil. Use of 10% KI solution - 30mg/month or 8mg every 2 weeks

Selenium

Food is the major source, Depends on soil conditionsGarlic, mushrooms, broccoli, fish, organ meatsRDI (WHO) is 40g/day

Importance in human was reported in 1979Protects against cancers and CVDMaintains healthy immune systemConstituent in several selenoproteins that are needed for thyroid metabolism, immune function, reproductive function

Function

In immune function role to play in the defense system (related to its antioxidant function)In cancer acts as an anti-carcinogenic agentIn CVD -

Metabolism

Main dietary form is selenoamino acidsMetabolism depends on the chemical formAbsorbed mainly from duodenum, high absorption about 80%. Selenomethionine is better absorbed than seleniteAbsorption is unaffected by Se statusSe status is influenced by dietary intakeExcretion through urine, unabsorbed through feces

Assessment of statusMainly by blood selenium levels (serum Se short term status and erythrocyte Se long term status)Urinary Se is also used

Fluoride

Acts to reduce dental caries inhibits bacterial enzymes that produce acid in plaques of teeth, erosion of dental enamel by acid is preventedSources drinking water, tea infusionsRDI is 0.5-1.0mg/day for children and 3-4mg/day for adults. Water supply should contain 0.7-1.0 ppm of fluoride

Copper

100mg Cu in the bodyPlasma Cu level is 15mol/L and up to 90% of this is associated with caeruloplasminCu has diverse functions erythropoiesis, connective tissue synthesis, oxidative phosphorylation, thermogenesisTransported as caeruloplasmin