TRACE EL­E­MENTS & HEALTH

The Gulf Today - Time Out - - TRAVEL - Dr Asheesh Mehta In­ter­nal Medicine Spe­cial­ist

Trace el­e­ments are com­po­nents of our diet which are re­quired in minute quan­ti­ties but are es­sen­tial for nor­mal growth and health. the main nu­tri­ents re­quired by us are pro­teins, car­bo­hy­drates and fats and they make up the macronu­tri­ents. the other sub­stances that are re­quired in very small quan­ti­ties are called mi­cronu­tri­ents. of the about 30 dif­fer­ent mi­cronu­tri­ents re­quired by us about half are the var­i­ous vi­ta­mins. some el­e­ments like sodium, potas­sium, phos­pho­rus, cal­cium and mag­ne­sium are re­quired in slightly larger quan­ti­ties while oth­ers are re­quired in truly minis­cule amounts. th­ese lat­ter are known as the trace el­e­ments. not­with­stand­ing the fact that their re­quire­ment is re­ally small, a deiciency of any of them has the po­ten­tial to cause sig­ni­icant clin­i­cal prob­lems. pres­ence of ex­ces­sive quan­ti­ties of trace el­e­ments in our body may also lead to ma­jor health prob­lems. the el­e­ments which are gen­er­ally con­sid­ered as trace el­e­ments from the nu­tri­tional point of view are io­dine, man­ganese, zinc, iron, chromium, se­le­nium, molyb­de­num, lu­o­rine, cop­per and cobalt. the com­mon­est trace el­e­ment deiciencies en­coun­tered clin­i­cally are those of iron and io­dine.

iron is crit­i­cal for oxy­gen trans­port and de­liv­ery. red blood cells con­tain haemoglobin of which iron is an in­te­gral com­po­nent. haemoglobin com­bines with oxy­gen when oxy­gen sat­u­ra­tion is high as oc­curs in our lungs. in tis­sues the oxy­gen sat­u­ra­tion is low and haemoglobin read­ily gives up oxy­gen for use by cells in meta­bolic pro­cesses in­clud­ing gen­er­a­tion of en­ergy. with­out oxy­gen tis­sues can­not sur­vive for long and some or­gans such as the brain can­not with­stand de­pri­va­tion of oxy­gen even for short pe­ri­ods. anaemia is the term used for a low haemoglobin level in blood. There are many causes of anaemia But Iron DEiCIEnCy Is the com­mon­est cause all over the world. It con­trib­utes to sub­stan­tial ill health and poor qual­ity of life in a sur­pris­ingly large per­cent­age of the global pop­u­la­tion. Iron is also a key com­po­nent of myo­globin which is a protein present in heart and other mus­cles. Myo­globin serves as a store for oxy­gen for uti­liza­tion dur­ing stren­u­ous ac­tiv­i­ties and also fa­cil­i­tates de­liv­ery of oxy­gen to mus­cle. The im­por­tance of myo­globin in pro­vid­ing a ready store of oxy­gen can be ap­pre­ci­ated from the fact that race­horses have un­usu­ally high lev­els of myo­globin in their mus­cles.

Although iron is es­sen­tial for nor­mal health, the re­quire­ment is very small. The rec­om­mended daily al­lowance (RDA) for an adult male is 8 mg. For adult fe­males the RDA is 18 mg as long as the men­strual cy­cle is still ac­tive and there­after it is 8 mg. The RDA dur­ing preg­nancy is sub­stan­tially higher at 27 mg. Iron is avail­able from nu­tri­tional sources in two forms. Heme iron is avail­able from lean meat and seafood. Non­heme iron sources in­clude veg­eta­bles, nuts and beans. in some coun­tries such as usa and canada lour and ce­re­als are fortiied with iron and such prod­ucts also be­come im­por­tant sources of iron. in gen­eral, heme iron is bet­ter ab­sorbed than non­heme iron. heme iron also helps ab­sorp­tion of non-heme iron. this is im­por­tant be­cause non-heme iron is more abun­dant in most peo­ple’s diet. breast milk con­tains iron suficient for the in­fant’s needs only till the age of about 4 to 6 months. in­fant for­mu­las are fortiied with iron. the prob­lem with iron, as with many other metal­lic el­e­ments, is that we can­not elim­i­nate ex­cess stores easily. iron in ex­cess of needs is harm­ful to us and to avoid ac­cu­mu­la­tion our body con­trols the ab­sorp­tion of iron in an elab­o­rate way. also, many fac­tors in­luence the ab­sorp­tion such as whether it is heme iron or non-heme iron. iron ab­sorp­tion is also af­fected by whether it is in the di­va­lent fer­rous or the triva­lent fer­ric form. the pres­ence of other sub­stances in food may en­hance or re­tard ab­sorp­tion of iron. for ex­am­ple, vi­ta­min c in food in­creases iron ab­sorp­tion while phy­tates present in some plant de­rived foods de­crease ab­sorp­tion of iron.

iron deiciency is much com­moner in women. they lose a lit­tle iron reg­u­larly from the blood low dur­ing the men­strual cy­cle. also, they have a higher re­quire­ment of iron dur­ing preg­nancy. blood loss due to any cause may lead to iron deiciency and anaemia. com­mon causes in­clude heavy men­strual bleed­ing, use of as­pirin and other nsaid pain killers which of­ten cause bleed­ing from the gas­troin­testi­nal tract and dis­eases of the gas­troin­testi­nal tract such as gas­tri­tis, ul­cer and oe­sophagi­tis. in en­demic ar­eas hook­worm in­fes­ta­tion is a very com­mon prob­lem. walk­ing bare­foot, usu­ally in some agri­cul­tural com­mu­ni­ties with prac­tice of de­fae­ca­tion in the open, al­lows hook­worm lar­vae to pen­e­trate in­tact skin of the foot and mi­grate to the duo­de­num in the small in­tes­tine. here they at­tach to the wall and suck blood. heavy in­fes­ta­tion is not at all un­com­mon and causes se­vere anaemia. the other ma­jor con­trib­u­tor to iron deiciency is poor nu­tri­tion.

iron deiciency is rel­a­tively easy to cor­rect pro­vided the un­der­ly­ing cause is at­tended to and fur­ther blood loss is pre­vented. oral iron is no­to­ri­ous for the com­plaints of in­tol­er­ance but most pa­tients can tol­er­ate lower doses. spe­cial prepa­ra­tions which cause less gas­troin­testi­nal dis­com­fort but are much costlier may also be bet­ter tol­er­ated. iron doses need to be taken af­ter food and may im­part a dark colour to stools. an al­ter­na­tive is in­jectable iron, prefer­ably as in­tra­venous in­jec­tion. the en­tire deicit can be made up by a sin­gle in­jec­tion in most cases. there is a small but deinite risk of se­vere re­ac­tion dur­ing in­tra­venous iron ad­min­is­tra­tion. when plan­ning this in­jec­tion ad­e­quate mon­i­tor­ing and avail­abil­ity of re­sus­ci­ta­tive mea­sures is a must.

ac­cu­mu­la­tion of iron in our bodies is also harm­ful. it causes what is called haemochro­mato­sis with main com­pli­ca­tions be­ing cir­rho­sis of liver and heart fail­ure. haemochro­mato­sis is a ge­netic dis­ease caus­ing an in­ap­pro­pri­ately high ab­sorp­tion of iron from the in­tes­tine. women are pro­tected to some de­gree by the safety valve of iron loss in men­strual low. sec­ondary haemochro­mato­sis may also oc­cur in peo­ple tak­ing too much iron. pa­tients with se­vere anaemia such as tha­las­saemia re­quire reg­u­lar trans­fu­sion. each trans­fu­sion rep­re­sents an iron load which can­not be elim­i­nated with­out spe­cial med­i­ca­tion. tak­ing too much oral iron, usu­ally as mis­guided med­i­ca­tion for anaemia not due to iron deiciency may also cause sec­ondary haemochro­mato­sis.

io­dine is an­other im­por­tant trace el­e­ment, be­ing a com­po­nent of thy­roid hor­mones. thy­roid hor­mones reg­u­late the body’s meta­bolic pro­cesses. our re­quire­ments of io­dine are minis­cule. the rda for adult men and women for io­dine is only 150 mi­cro­grams (0.15 mg). women who are preg­nant or are breast­feed­ing are rec­om­mended to take 220 and 290 mi­cro­gram io­dine re­spec­tively. how­ever, nat­u­ral sources of io­dine are lim­ited to seafood and sea salt. peo­ple liv­ing in hilly in­land ar­eas and us­ing salt de­rived from rock rather than from sea wa­ter used to be at sub­stan­tial risk for io­dine deiciency. most health au­thor­i­ties have im­ple­mented the sim­ple ex­pe­di­ent of adding a small quan­tity of io­dine to salt avail­able in the mar­ket to pre­vent io­dine deiciency. iodized salt usu­ally con­tains about 400 mi­cro­gram io­dine in a tea­spoon. the thy­roid takes up io­dine avidly. should io­dine be deicient the thy­roid en­larges in an at­tempt to achieve its goal of pro­duc­ing ad­e­quate quan­ti­ties of thy­roid hor­mones. en­large­ment of the thy­roid is called a goitre

and with se­vere io­dine deiciency a goitre can at­tain an enor­mous size. more im­por­tantly, the lack of thy­roid hor­mones re­sults in clin­i­cal hy­pothy­roidism. a deiciency of thy­roid hor­mones dur­ing foetal stage or in early child­hood is re­ally dis­as­trous as it re­sults in the con­di­tion called cre­tinism. the cretin suf­fers per­ma­nent men­tal and phys­i­cal re­tar­da­tion which can­not be cor­rected by io­dine sup­ple­men­ta­tion or ad­min­is­tra­tion of thy­roid hor­mones later in life. the ef­fects of deiciency of thy­roid hor­mones cause sig­ni­icant clin­i­cal prob­lems in adults too. for­tu­nately, wide­spread iodi­s­a­tion of salt has re­duced the oc­cur­rence of io­dine deiciency and re­sul­tant thy­roid deiciency dis­or­ders to a great ex­tent. many peo­ple, how­ever, do opt for non­iodised salt and may be at risk for io­dine deiciency. tak­ing too much io­dine is also haz­ardous. this too may be as­so­ci­ated with de­vel­op­ment of a goitre and dis­tur­bances in pro­duc­tion of thy­roid hor­mones. there is also a risk of de­vel­op­ment of thy­roid pap­il­lary can­cer when tak­ing in too much io­dine on a long-term ba­sis.

while deiciency of iron and of io­dine are the com­mon­est trace el­e­ment dis­or­ders the other trace el­e­ments also serve crit­i­cal func­tions and may cause clin­i­cal dis­ease, although less com­monly. in gen­eral, un­less one lives in an

area of en­demic deiciency, th­ese trace el­e­ment dis­or­ders can be avoided by eat­ing a nor­mal bal­anced diet. sup­ple­men­ta­tion is usu­ally not re­quired un­less one’s diet is un­sat­is­fac­tory.

Iron is crit­i­cal for oxy­gen trans­port and de­liv­ery. Red blood cells con­tain haemoglobin of which iron is an in­te­gral com­po­nent. Haemoglobin com­bines with oxy­gen when oxy­gen sat­u­ra­tion is high as oc­curs in our lungs

Newspapers in English

Newspapers from UAE

© PressReader. All rights reserved.