Folate and vitamin B12 status in relation to cognitive impairment and anaemia in the setting of voluntary fortification in the UK.

Concerns about risks for older people with vitamin B12 deficiency have delayed the introduction of mandatory folic acid fortification in the UK. We examined the risks of anaemia and cognitive impairment in older people with low B12 and high folate status in the setting of voluntary fortification in the UK. Data were obtained from two cross-sectional studies (n 2403) conducted in Oxford city and Banbury in 1995 and 2003, respectively.

Detection of vitamin B12 deficiency in older people by measuring vitamin B12 or the active fraction of vitamin B12, holotranscobalamin.

Background: Impaired vitamin B(12) function and decreased vitamin B(12) status have been associated with neurological and cognitive impairment. Current assays analyze total vitamin B(12) concentration, only a small percentage of which is metabolically active. Concentrations of this active component, carried on holotranscobalamin (holoTC), may be of greater relevance than total vitamin B(12).

Clinical relevance of low serum vitamin B12 concentrations in older people: the Banbury B12 study.

Background: low vitamin B12 concentrations are common in older people, but the clinical relevance of biochemical evidence of vitamin B12 deficiency in the absence of anaemia is uncertain.

Objective: to examine associations of cognitive impairment, depression and neuropathy with blood measurements of vitamin B12 and folate status in older people.

Design: cross-sectional study in general practice in Banbury, England.

Evaluation of the technical performance of novel holotranscobalamin (holoTC) assays in a multicenter European demonstration project.

A commercially available holotranscobalamin (holo-TC) radioimmunoassay (RIA) (Axis-Shield, Dundee, Scotland) was evaluated in four laboratories and compared with a holoTC ELISA run in one laboratory. The performance of the holoTC RIA assay was comparable in three of the four participating laboratories. The results from these three laboratories, involving at least 20 initial runs of "low", "medium" and "high" serum-based controls (mean holoTC concentrations 34, 60 and 110 pmol/L, respectively) yielded an intra-laboratory imprecision of 6-10%.