Does vi­ta­min D help pro­tect against Covid-19?

Hindustan Times (Jalandhar) - - HTSPOTLIGH­T - SAN­CHITA SHARMA

NEW DELHI: Older and dark­er­skinned peo­ple who are likely to have low lev­els of Vi­ta­min D may ben­e­fit from sup­ple­men­ta­tion of the es­sen­tial vi­ta­min to pro­tect against se­vere symp­toms of the coron­avirus disease (Covid-19), ac­cord­ing to a pa­per pub­lished in The Lancet. Clin­i­cians, how­ever, say that dos­ing on the vi­ta­min in hope of be­ing pro­tected from the in­fec­tion is a fal­lacy, as the best and only pro­tec­tion against in­fec­tion re­mains hand-wash, wear­ing masks and so­cial iso­la­tion.

Vi­ta­min D is made by the skin on ex­po­sure to sun­light and is es­sen­tial for bone growth and strength as it helps in the in­testi­nal ab­sorp­tion of cal­cium, mag­ne­sium, and phos­phate. This fat-sol­u­ble vi­ta­min also mod­u­lates the im­mune re­sponse of white blood cells by pre­vent­ing them from re­leas­ing too many in­flam­ma­tory cy­tokines, which is what leads to the cy­tokine storm — a com­pli­ca­tion associated with Covid-19 and other disease such as se­vere acute res­pi­ra­tory syn­drome (Sars) and mid­dle-east res­pi­ra­tory syn­drome (Mers). Cy­tokine storm is an acute im­mune re­ac­tion gone awry as the body starts de­stroy­ing its own cells and tis­sues along with the virus.

Me­lanin, which gives skin the dark pig­men­ta­tion, low­ers the skin’s abil­ity to make vi­ta­min D on ex­po­sure to sun­light, with sev­eral stud­ies show­ing that older adults with darker skin are more likely to be deficit in this es­sen­tial vi­ta­min. With so­cial iso­la­tion forc­ing peo­ple to spend more time in­doors, the de­fi­ciency of this vi­ta­min may be in­creas­ing, said The Lancet study. Around 50% In­di­ans are deficit in vi­ta­min D, which is now found in some brands of for­ti­fied milk, in­clud­ing Mother

Dairy. The over­all preva­lence of vi­ta­min D de­fi­ciency in peo­ple liv­ing in ur­ban Chen­nai was 55%, found a re­cent sur­vey of 1,500 peo­ple pub­lished in the Bri­tish Jour­nal of Nutri­tion on March 26.

“Our study found that vi­ta­min D de­fi­ciency was 63% in peo­ple with di­a­betes, 58% in peo­ple with pre-di­a­betes, and 80% in obese peo­ple, which is wor­ry­ing be­cause th­ese are risk fac­tors for Covid-19,” says Dr V Mo­han, study co-au­thor and chair­man and chief of di­a­betol­ogy at Dr Mo­han’s Di­a­betes Spe­cial­i­ties Cen­tre, which is a WHO Col­lab­o­rat­ing Cen­tre for Non­com­mu­ni­ca­ble Dis­eases Preven­tion and Con­trol.

“Ob­ser­va­tional stud­ies in the past have linked low lev­els of vi­ta­min D and sus­cep­ti­bil­ity to acute res­pi­ra­tory tract in­fec­tions. Sup­ple­men­ta­tion is in­ex­pen­sive and the dan­ger of side effects and tox­i­c­ity are low when taken orally. The risk of tox­i­c­ity is high for peo­ple with kid­ney and liver dis­eases as they may not be able to ex­crete the vi­ta­min, so they should not take sup­ple­men­ta­tion with­out pre­scrip­tion,” said Dr Mo­han.

The Lancet pa­per cites vi­ta­min D de­fi­ciency as one of the pos­si­ble rea­sons for vary­ing death rates across coun­tries cit­ing an ob­ser­va­tional study pub­lished in the jour­nal Ag­ing Clin­i­cal and Ex­per­i­men­tal Re­search that used data from 20 Euro­pean coun­tries. It noted that av­er­age vi­ta­min D lev­els are low in Italy and Spain, which have ex­pe­ri­enced high Covid-19 death rates com­pared to north Euro­pean coun­tries, which have high av­er­age lev­els of vi­ta­min D from the con­sump­tion of cod liver oil and vi­ta­min D sup­ple­ments, and pos­si­bly less sun avoid­ance.

“Vi­ta­min D might help to re­duce the in­flam­ma­tory re­sponse to in­fec­tion with SarsCoV-2. Dereg­u­la­tion of this re­sponse... is char­ac­ter­is­tic of COVID-19 and de­gree of over­ac­ti­va­tion is associated with poorer prog­no­sis. e,” ac­cord­ing to The Lancet pa­per.

An ob­ser­va­tional cor­re­la­tion, how­ever, does not mean cau­sa­tion, say experts. “In­ter­ven­tion tri­als have rarely shown ben­e­fits of vi­ta­min D sup­ple­men­ta­tion as treat­ment, ex­cept for mus­cu­lar-skele­tal dis­or­ders. Stud­ies link­ing vi­ta­min D sup­ple­men­ta­tion to lung dis­eases like tu­ber­cu­lo­sis and COPD (chronic ob­struc­tive lung disease) have demon­strated no dif­fer­ence to clin­i­cal out­comes,” said Dr Nikhil Tan­don, pro­fes­sor of en­docrinol­ogy and me­tab­o­lism at the All In­dia In­sti­tute of Med­i­cal Sciences.

“Ob­ser­va­tional stud­ies can­not be used to in­form pub­lic pol­icy and un­less there is clin­i­cal data to show that it has a sub­stan­tial af­fect on the out­comes of Covid-19, hav­ing it in the hope or anticipati­on that it will pro­tect you against disease is point­less. It may bring you other ben­e­fits if you are deficit, but it will not stop you get­ting Covid-19 the way masks, hand­wash­ing and so­cial iso­la­tion will,” said Dr Tan­don.

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