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Apparent Vitamin D Deficiencies in Blacks: Protein Variant at Fault? — Physician’s First Watch

Medical News |
November 21, 2013

Apparent Vitamin D Deficiencies in Blacks: Protein Variant at Fault?

By Joe Elia

The apparently high prevalence of vitamin D deficiency among blacks may be an artifact of what form is measured clinically, according to a New England Journal of Medicine study.

Among a sample of some 2100 blacks and whites, mean levels both of total 25-hydroxyvitamin D and of vitamin D-binding protein were lower among blacks. Yet blacks had higher bone mineral densities than whites and similar levels of bioavailable vitamin D.

The explanation may lie with variation in a gene associated with vitamin D-binding protein. The variant more prevalent among blacks is associated with lower levels of the binding protein. (Whites with the variant protein also showed lower binding levels.)

The authors conclude that low levels of 25-hydroxyvitamin D don't necessarily indicate a deficiency. Their results, they say, "call into question routine supplementation in persons with low levels of both total 25-hydroxyvitamin D and vitamin D-binding protein." They recommend that "to improve the determination of vitamin D status in diverse populations [measuring the binding protein] will most likely need to be incorporated."

Reader Comments (12)

AHMAD KHATIB Physician, Family Medicine/General Practice, PSMMC RIYADH KSA

Please every body we should spread out such information, to convince some of our colleagues who likes to stress on vit D level every 3 month, and also the media which overestimated this problem and frightened everyone.

Mustafa Al-abousi PhD,Endocrinilogist,Shatti Alqurum center,Oman Physician, Endocrinology

In our region i.e middle east ,more than 85% of examined pts have severe vit D def., inspite the majority are healthy outdoor working men , Im absolutely agree with this article.

Maxwell Hopp

Does anyone have any idea how this applies to other (non black) pigmented races, ie Indians

Jameel ur Rahman FCPS, MRCP(UK) Physician, Internal Medicine, Ain Al Khaleej Hospital Al Ain, UAE

Good point raised. I am always thinking there is a missing unexplained link. How then here, even in those who are working in sun by the nature of their job are low in Vit D.

Andrew Meeks FRCPCH Physician, Pediatric Subspecialty, Abu Dhabi

ad hoc measurements of circulating vitamin D during pregnancy of mothers whose babies are admitted to the neonatal unit show that despite supplementation, the vast majority have low levels
the numbers are to small to comment upon effects on their babies, but we do not associate any markers in biochemistry or radiology that would make us suspect that a mother might be vitamin deficient
anecdote rather than study, of course, but we have to start somewhere
anyone interested in possible collaboration?

Udaya M Kabadi Physician, Endocrinology, Unversity of iowa , Broadlawns Mwdical center, Des Moines

Always told my colleagues, Feloows , Residents and student that that Vit D deficiency could never be so prevalent and the methodology for mesurementis likely to be erroneous. also told that real deficiency could be documented by determining Free Vit D level and not 'total' vit D level.

MD Physician, Gastroenterology, VA Med center

Useful

Bhoopendra Datta MD Physician, Pathology, Chandigarh India

Finally some one has looked into this dichotomy between low serum vit D levels , life in abundant sunlight and no bone disorder. The usual commercial interests at play again in propagating vitamin D deficiency in the tropics and in US black population : ??? the lab estimation kit manufacturers and vitamin D manufacturers who sold the concept of vit D deficiencies in such populations

LEO INGLE, M.D. Physician, Psychiatry, Solo Practice

The relentless attack by the "medical establishment" on supplements continues. Mostly, it is an attack focusing on the scarcity of evidence, though that is susceptible by the principle that "absence of evidence is not evidence of absence" and the unavailability of funds for supplement research, lacking the incentive of lavishly rewarded patents. This article is more circumspect, but a casual reader might not pick up the suggestion to augment the tests, and only "learn" to disregard Vitamin D levels.

Morris L . Orocofsky M.D. Physician, Internal Medicine, Interfaith Community Clinic

Are there confounders with differences in resistive exercise between the populations?

Morris L . Orocofsky M.D. Physician, Internal Medicine, Interfaith Community Clinic

Are there confounders with differences in resistive exercise between the populations?

omar al farouk Physician, Pediatrics/Adolescent Medicine, ZMH UAE

vit.D def. is over diagnosed

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