MICRONUTRIENTS & HEALTH

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

Werequi­reava­ri­ety of nu­tri­ent sub­stances to meet en­ergy re­quire­ments and to keep our bod­ies healthy. Some of these sub­stances are re­quired in rel­a­tively large quan­ti­ties and they are con­ven­tion­ally termed macronu­tri­ents. These are the pro­teins, car­bo­hy­drates and fats which make up the bulk of our nu­tri­tional re­quire­ments. Other sub­stances are re­quired in minute quan­ti­ties and are termed micronutrients. Even though the re­quire­ment of these micronutrients is very small, their need is crit­i­cal and de­iciency re­sults in sig­ni­icant clin­i­cal prob­lems. There are about 30 such nu­tri­ents which are re­quired in trace amounts and so qual­ify to be termed as micronutrients. Ex­am­ples of micronutrients in­clude the var­i­ous vi­ta­mins and trace el­e­ments such as cal­cium, iron, zinc, cop­per, etc.

Vi­ta­mins are or­ganic com­pounds ob­tain­able from diet which are es­sen­tial for health and nor­mal func­tion­ing of the body and which can­not be syn­the­sised by the body. Vi­ta­mins are des­ig­nated by a cap­i­tal let­ter with a num­ber also be­ing used to iden­tify some of them. The main vi­ta­mins are vi­ta­min A, those of the B group, C, D, E and K. Vi­ta­mins are con­ven­tion­ally di­vided into two classes – wa­ter sol­u­ble and fat sol­u­ble vi­ta­mins. Vi­ta­mins A, D, E and K are fat sol­u­ble while vi­ta­mins of the B group and vi­ta­min C are wa­ter

Vi­ta­mins are or­ganic com­pounds ob­tain­able from diet which are es­sen­tial for health and nor­mal func­tion­ing of the body and which can­not be syn­the­sised by the body. Vi­ta­mins are des­ig­nated by a cap­i­tal let­ter with a num­ber also be­ing used to iden­tify some of them

sol­u­ble. As a gen­eral rule, wa­ter sol­u­ble vi­ta­mins do not ac­cu­mu­late in our body even when we take large doses. Ex­cess amounts are elim­i­nated fairly eas­ily, thus pre­vent­ing build up. Fat sol­u­ble vi­ta­mins on the other hand can­not be eas­ily elim­i­nated and when taken in ex­cess, they can ac­cu­mu­late and cause tox­i­c­ity. Such a state of af­fairs al­most never arises due to ex­ces­sive di­etary in­take but does oc­cur from oral or in­jectable ad­min­is­tra­tion of large doses of vi­ta­min prepa­ra­tions.

The in­di­vid­ual vi­ta­mins have var­ied func­tions which are by and large un­re­lated to each other. Pro­vided one eats a nor­mal rea­son­ably bal­anced diet oc­cur­rence of vi­ta­min de­iciency for most of the vi­ta­mins is rare. How­ever, when diet is not nu­tri­tious as may oc­cur in famine con­di­tions or as a re­sult of so­cial or med­i­cal prob­lems in­clud­ing al­co­holism or drug ad­dic­tion vi­ta­min de­iciency does de­velop. Peo­ple ex­ces­sively picky in their se­lec­tion of foods or those fol­low­ing speciic di­ets for re­li­gious pur­poses or as a mat­ter of choice too are vul­ner­a­ble to de­velop such de­icien­cies. One of the clas­si­cal ex­am­ples is the oc­cur­rence of scurvy in sailors in olden times. This is a vi­ta­min C de­iciency dis­ease. Dur­ing long sea voy­ages sailors had no ac­cess to fresh fruit or veg­eta­bles, the main sources of vi­ta­min C. This re­sulted in scurvy which is as­so­ci­ated with weak­ness and marked fa­tigue, bleed­ing from gums, swelling of feet

and anaemia and in­ally death if left un­treated for long. The pre­ven­tive and cu­ra­tive ef­fects of lemons and other cit­rus fruits was dis­cov­ered more than two cen­turies back. Over time, scurvy has be­come an ex­tremely rare dis­ease be­ing seen only in ex­cep­tional cir­cum­stances of se­vere mal­nu­tri­tion. De­iciency of vi­ta­min A is still a sig­ni­icant prob­lem in some de­vel­op­ing coun­tries and this can lead to blind­ness. Ad­min­is­ter­ing vi­ta­min A sup­ple­ments to chil­dren in af­fected com­mu­ni­ties has been found to be very ef­fec­tive in com­bat­ing such de­iciency and pre­vent­ing blind­ness.

In peo­ple eat­ing a nor­mal diet the only vi­ta­min de­icien­cies that oc­cur with any sig­ni­icant fre­quency are of vi­ta­min D and vi­ta­min

B12. Re­gard­ing vi­ta­min D it can be con­tested that it should not be called a vi­ta­min at all since it is pos­si­ble for it to be pro­duced in our skin by the ac­tion of sun­light. In spite of this pos­si­bil­ity to make the vi­ta­min our­selves and also in spite of for­ti­ica­tion of foods such as dairy prod­ucts with vi­ta­min D, de­iciency con­tin­ues to be very com­mon. It is true that most of us liv­ing in the UAE avoid di­rect ex­po­sure to the sun for com­mon sense rea­sons. De­iciency of vi­ta­min D causes mild and rel­a­tively non­speciic symp­toms such as bone pains and fa­tigue in most af­fected in­di­vid­u­als. Vi­ta­min D de­iciency is also be­lieved to in­crease the risk for car­dio­vas­cu­lar dis­ease and some types of can­cer. Se­vere vi­ta­min D de­iciency that causes the child­hood

syn­drome of rick­ets and the adult syn­drome of os­teo­ma­la­cia is seen with any de­gree of fre­quency only in ar­eas of the world aflicted by se­vere mal­nu­tri­tion. Vi­ta­min D de­iciency is treated with sup­ple­ments of vi­ta­min D. Sup­ple­ments are avail­able in small doses for preven­tion and much higher doses for treat­ing es­tab­lished de­iciency. Since vi­ta­min

D can ac­cu­mu­late in the body when ex­ces­sive doses are ad­min­is­tered, cau­tion needs to be ex­er­cised when tak­ing high doses. Also, the re­ally high dose (50,000 IU) oral prepa­ra­tions are rec­om­mended for once a week us­age and this fre­quency should not be ex­ceeded.

Vi­ta­min B12 is the other vi­ta­min de­iciency which is rel­a­tively com­mon. This vi­ta­min can be sourced only from an­i­mal de­rived foods. Peo­ple who fol­low a vege­tar­ian or ve­gan diet are thus ren­dered vul­ner­a­ble to this de­iciency. Other in­di­vid­u­als may also de­velop vi­ta­min B12 de­iciency but it is gen­er­ally less com­mon and less se­vere. Vi­ta­min B12 de­iciency also oc­curs due to in­ad­e­quate pro­duc­tion of a spe­cial protein called in­trin­sic fac­tor by cer­tain cells lin­ing the stom­ach. Ab­sorp­tion of vi­ta­min B12 takes place in the small in­tes­tine but de­pends on the pres­ence of in­trin­sic fac­tor. The clas­si­cal form is called per­ni­cious anaemia and oc­curs as an in­her­ited dis­ease in which one’s own an­ti­bod­ies act against stom­ach cells pro­duc­ing in­trin­sic fac­tor. Surgery

on the stom­ach which re­moves this part of the stom­ach causes a sim­i­lar de­iciency of in­trin­sic fac­tor lead­ing to vi­ta­min B12 de­iciency. Dis­eases of the small in­tes­tine or surgery too may cause vi­ta­min

B12 de­iciency as this is the site of ab­sorp­tion of the vi­ta­min. De­iciency of vi­ta­min B12 causes anaemia and it causes neu­ro­log­i­cal prob­lems. Symp­toms of the former in­clude fa­tigue, weak­ness, breath­less­ness, pal­pi­ta­tions, dizzi­ness, etc. In later stages car­diac fail­ure oc­curs. Neu­ro­log­i­cal symp­toms of vi­ta­min B12 de­iciency in­clude tin­gling and numb­ness in the lower limbs pro­gress­ing to weak­ness and un­steady gait. In older in­di­vid­u­als it can cause symp­toms such as me­mory loss and de­te­ri­o­ra­tion of other in­tel­lec­tual func­tions which may be mis­di­ag­nosed as Alzheimer’s dis­ease. Se­vere vi­ta­min B12 de­iciency is a se­ri­ous and po­ten­tially fa­tal dis­ease. The rec­om­mended daily al­lowance (RDA) for Vi­ta­min B12 is 2.4 mcg. This amount is read­ily avail­able from diet in peo­ple eat­ing a non­veg­e­tar­ian diet. Most multi-vi­ta­min pills used as gen­eral health sup­ple­ments con­tain amounts ad­e­quate to pre­vent de­iciency symp­toms from de­vel­op­ing even in strict veg­e­tar­i­ans. Since in­trin­sic fac­tor is re­quired for vi­ta­min B12 ab­sorp­tion, peo­ple lack­ing this sub­stance can­not ab­sorb vi­ta­min B12 and hence oral doses are not rec­om­mended. How­ever, high dose vi­ta­min B12 (1000 mcg) oral prepa­ra­tions are avail­able and at this con­cen­tra­tion some ab­sorp­tion does oc­cur even with­out in­trin­sic fac­tor. How­ever, since the ab­sorp­tion in such cases is fairly er­ratic and un­re­li­able, a monthly in­jec­tion of vi­ta­min B12 is a bet­ter idea. In­jec­tion doses are gen­er­ally of 1000 mcg which is more than ad­e­quate to cover the monthly re­quire­ment. Since un­re­quired vi­ta­min is eas­ily elim­i­nated from the body, tox­i­c­ity from ac­cu­mu­la­tion is not a fear.

That de­iciency of vi­ta­mins has the po­ten­tial to cause se­ri­ous ill­ness is un­doubted. How­ever, vi­ta­mins have al­most no beneits ex­cept to pre­vent de­iciency re­lated dis­eases. They are not magic sub­stances that pre­vent or avert dis­eases un­re­lated to de­iciency. They also do not have any in­vig­o­rat­ing prop­er­ties pro­vid­ing strength and en­ergy or make peo­ple feel or look younger. Vi­ta­min prepa­ra­tions are meant only to pre­vent or treat de­iciency states. Us­ing them to de­rive any other type of beneit is at best hope­ful think­ing and at worst a health haz­ard. Most peo­ple eat­ing a bal­anced and healthy diet do not need vi­ta­min sup­ple­ments. Al­though there is no real harm in tak­ing a stan­dard dose multi-vi­ta­min pill daily, one should not ex­pect any mean­ing­ful beneit be­yond a placebo ef­fect. How­ever, tak­ing high dose vi­ta­min pills or in­jec­tions is po­ten­tially harm­ful and this ap­plies spe­cially to prepa­ra­tions of vi­ta­mins D and A.

The other group of sub­stances that are con­sid­ered as micronutrients are the trace el­e­ments. These too are re­quired in minute quan­ti­ties to serve di­verse and crit­i­cal func­tions in our body. De­iciency or ex­cess of these sub­stances leads to ma­jor clin­i­cal prob­lems. Some of the dis­eases are in­her­ited while oth­ers are ac­quired due to di­verse causes such as nu­tri­tional and en­vi­ron­men­tal prob­lems. The im­por­tance and im­pact of some of these trace el­e­ments on our health is con­sid­ered next week.

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