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A vitamin B-12 supplement of 500 µg/d for eight weeks does not normalize urinary methylmalonic acid or other biomarkers of vitamin B-12 status in elderly people with moderately poor vitamin B-12 status.
Hill, Marilyn H; Flatley, Janet E; Barker, Margo E; Garner, Clare M; Manning, Nigel J; Olpin, Simon E; Moat, Stuart J; Russell, Jean; Powers, Hilary J.
Afiliação
  • Hill MH; Human Nutrition Unit, Department of Oncology, Faculty of Medicine, Dentistry and Health, University of Sheffield, Sheffield, UK.
J Nutr ; 143(2): 142-7, 2013 Feb.
Article em En | MEDLINE | ID: mdl-23236022
Plasma vitamin B-12 is the most commonly used biomarker of vitamin B-12 status, but the predictive value for low vitamin B-12 status is poor. The urinary methylmalonic acid (uMMA) concentration has potential as a functional biomarker of vitamin B-12 status, but the response to supplemental vitamin B-12 is uncertain. A study was conducted to investigate the responsiveness of uMMA to supplemental vitamin B-12 in comparison with other biomarkers of vitamin B-12 status [plasma vitamin B-12, serum holotranscobalamin (holoTC), plasma MMA] in elderly people with moderately poor vitamin B-12 status. A double-blind, placebo-controlled, randomized 8-wk intervention study was carried out using vitamin B-12 supplements (500 µg/d, 100 µg/d, and 10 µg/d cyanocobalamin) in 100 elderly people with a combined plasma vitamin B-12 <250 pmol/L and uMMA ratio (µmol MMA/mmol creatinine) >1.5. All biomarkers had a dose response to supplemental vitamin B-12. Improvements in plasma vitamin B-12 and serum holoTC were achieved at cobalamin supplements of 10 µg/d, but even 500 µg/d for 8 wk did not normalize plasma vitamin B-12 in 8% and serum holoTC in 12% of people. The response in uMMA was comparable with plasma MMA; 15-25% of people still showed evidence of metabolic deficiency after 500 µg/d cobalamin for 8 wk. There was a differential response in urinary and plasma MMA according to smoking behavior; the response was enhanced in ex-smokers compared with never-smokers. uMMA offers an alternative marker of metabolic vitamin-B12 status, obviating the need for blood sampling.
Assuntos

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Vitamina B 12 / Deficiência de Vitamina B 12 / Envelhecimento / Estado Nutricional / Suplementos Nutricionais / Ácido Metilmalônico Tipo de estudo: Clinical_trials / Observational_studies / Prevalence_studies / Prognostic_studies / Risk_factors_studies Limite: Aged / Aged80 / Female / Humans / Male Idioma: En Revista: J Nutr Ano de publicação: 2013 Tipo de documento: Article

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Vitamina B 12 / Deficiência de Vitamina B 12 / Envelhecimento / Estado Nutricional / Suplementos Nutricionais / Ácido Metilmalônico Tipo de estudo: Clinical_trials / Observational_studies / Prevalence_studies / Prognostic_studies / Risk_factors_studies Limite: Aged / Aged80 / Female / Humans / Male Idioma: En Revista: J Nutr Ano de publicação: 2013 Tipo de documento: Article