Para avaliar a prevalência da deficiência de vitamina B12 e folato na população idosa do Reino Unido, pacientes de uma amostra significativa da população foram submetidos a um estudo transversal realizado por pesquisadores ligados ao Clinical Trial Service Unit and Epidemiological Studies Unit, do Nuffield Department of Clinical Medicine, da Radcliffe Infirmary. Publicado no periódico Age and Ageing, o estudo sugere que os baixos níveis séricos de B12 e folato observados indicam a necessidade de medidas de vigilância epidemiológica focadas nesta população.
Age and Ageing
Age and Ageing 2004; 33: 34-41
© 2004, British Geriatrics Society
Vitamin B12 and folate deficiency in later life
Robert Clarke1, J. Grimley Evans2, J. Schneede4, E. Nexo5, C. Bates6, A. Fletcher7, A. Prentice6, C. Johnston3, P. M. Ueland4, H. Refsum4, P. Sherliker1, J. Birks2, G. Whitlock1, E. Breeze7 and J. M. Scott8
1 Clinical Trial Service Unit
2 Division of Clinical Geratology
3 University Department of Pharmacology, University of Oxford, Oxford, UK
4 Department of Pharmacology, University of Bergen, Norway
5 Department of Clinical Biochemistry, AKH, Aarhus University Hospital, Aarhus, Denmark
6 MRC Human Nutrition Research, Cambridge, UK
7 Centre for Ageing and Public Health, London School of Hygiene and Tropical Medicine, London, UK
8 Department of Biochemistry, Trinity College, Dublin, Ireland
Correspondence: Address correspondence to: R. Clarke, Clinical Trial Service Unit and Epidemiological Studies Unit, Nuffield Department of Clinical Medicine, Radcliffe Infirmary, Oxford OX2 6HE, UK. Fax: (+44) 1865-55881. Email: robert.clarke@ctsu.ox.ac.uk
Abstract
Objectives: to examine the prevalence of vitamin B12 deficiency and folate deficiency in later life in representative samples of the elderly population in the United Kingdom.
Design: a population-based cross-sectional analysis of 3,511 people aged 65 years or older from three studies was used to estimate the age-specific prevalence of vitamin B12 deficiency and of folate deficiency. Vitamin B12 deficiency is conventionally diagnosed if serum vitamin B12 < 150 pmol/l (‘low vitamin B12’). We defined ‘metabolically significant vitamin B12 deficiency’ as vitamin B12 < 200 pmol/l and blood total homocysteine >20 µmol/l. Folate deficiency, which usually refers to serum folate <5 nmol/l, was defined as ‘metabolically significant’ if serum folate was <7 nmol/l and homocysteine >20 µmol/l.
Results: the prevalence of vitamin B12 deficiency, whether defined as low vitamin B12 or metabolically significant vitamin B12 deficiency increased with age in all three studies, from about 1 in 20 among people aged 65–74 years to 1 in 10 or even greater among people aged 75 years or greater. The prevalence of folate deficiency also increased with age, and was similar to that for vitamin B12 deficiencies, but only about 10% of people with low vitamin B12 levels also had low folate levels.
Conclusion: the high prevalence of vitamin B12 and folate deficiency observed in older people indicates a particular need for vigilance for deficiency of these vitamins. Reliable detection and treatment of vitamin deficiency could reduce the risk of deficiency-related disability in old age.
Key Words: vitamin B12 • folate • age • folate deficiency in later life
Received for publication May 7, 2002. Revision received June 11, 2003. Accepted for publication June 11, 2003.
