title: Vitamin B12 and folate deficiency in later life.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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 micro mol/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 micro mol/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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Clinical Trial Service Unit. Division of Clinical Geratology. University Department of Pharmacology, University of Oxford, Oxford, UK. robert.clarke@ctsu.ox.ac.uk
authors.forename: Robert
authors.initials: R
authors.lastname: Clarke
authors.forename: J
authors.initials: J
authors.lastname: Grimley Evans
authors.forename: J
authors.initials: J
authors.lastname: Schneede
authors.forename: E
authors.initials: E
authors.lastname: Nexo
authors.forename: C
authors.initials: C
authors.lastname: Bates
authors.forename: A
authors.initials: A
authors.lastname: Fletcher
authors.forename: A
authors.initials: A
authors.lastname: Prentice
authors.forename: C
authors.initials: C
authors.lastname: Johnston
authors.forename: P M
authors.initials: PM
authors.lastname: Ueland
authors.forename: H
authors.initials: H
authors.lastname: Refsum
authors.forename: P
authors.initials: P
authors.lastname: Sherliker
authors.forename: J
authors.initials: J
authors.lastname: Birks
authors.forename: G
authors.initials: G
authors.lastname: Whitlock
authors.forename: E
authors.initials: E
authors.lastname: Breeze
authors.forename: J M
authors.initials: JM
authors.lastname: Scott
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D005492:Folic Acid / Q000097:blood; D005494:Folic Acid Deficiency / Q000453:epidemiology*; D006710:Homocysteine / Q000097:blood; D006801:Humans; D007326:Institutionalization; D015995:Prevalence; D006113:United Kingdom / Q000453:epidemiology; D014805:Vitamin B 12 / Q000097:blood; D014806:Vitamin B 12 Deficiency / Q000453:epidemiology*
chemical_list: D006710:Homocysteine; D005492:Folic Acid; D014805:Vitamin B 12