QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Online Supplemental Material All Versions of this Article: 139/11/2119    most recent jn.109.107359v1 Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Bhat, D. S. Articles by Yajnik, C. S. PubMed PubMed Citation Articles by Bhat, D. S. Articles by Yajnik, C. S.

---

Nutritional Epidemiology

Increases in Plasma Holotranscobalamin Can Be Used to Assess Vitamin B-12 Absorption in Individuals with Low Plasma Vitamin B-12^1–3,

⁴ Kamalnayan Bajaj Diabetology Research Centre, King Edward Memorial Hospital Research Centre, Pune 411011, India; ⁵ Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX13QX, UK; ⁶ Institute of Basic Medical Sciences, Department of Nutrition, University of Oslo, Oslo 0316, Norway; and ⁷ MRC Epidemiology Resource Centre, University of Southampton, Southampton SO16 6YD, UK

Low plasma concentrations of vitamin B-12 are common in Indians, possibly due to low dietary intakes of animal-source foods. Whether malabsorption of the vitamin contributes to this has not been investigated. A rise in the plasma holotranscobalamin (holo-TC) concentration after a standard dose of oral vitamin B-12 has been proposed as a measure of gastrointestinal absorption in people with normal plasma vitamin B-12 concentrations. We studied 313 individuals (children and parents, 109 families) in the Pune Maternal Nutrition Study. They received 3 doses of 10 µg (n = 191) or 2 µg (n = 122) of cyanocobalamin at 6-h intervals. A rise in plasma holo-TC of 15% and >15 pmol/L above baseline was considered normal vitamin B-12 absorption. The baseline plasma vitamin B-12 concentration was <150 pmol/L in 48% of participants; holo-TC was <35 pmol/L in 98% and total homocysteine was high in 50% of participants (>10 µmol/L in children and >15 µmol/L in adults). In the 10 µg group, the plasma holo-TC concentration increased by 4.8-fold from (mean ± SD) 9.3 ± 7.0 pmol/L to 53.8 ± 25.9 pmol/L and in the 2 µg group by 2.2-fold from 11.1 ± 8.5 pmol/L to 35.7 ± 19.3 pmol/L. Only 10% of the participants, mostly fathers, had an increase less than the suggested cut-points. Our results suggest that an increase in plasma holo-TC may be used to assess vitamin B-12 absorption in individuals with low vitamin B-12 status. Because malabsorption is unlikely to be a major reason for the low plasma vitamin B-12 concentrations in this population, increasing dietary vitamin B-12 should improve their status.

^* To whom correspondence should be addressed. E-mail: diabetes{at}vsnl.com.

Manuscript received 27 March 2009. Initial review completed 5 May 2009. Revision accepted 10 September 2009.

Published online 23 September 2009.