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- Clarke, Robert, et al.
(author)
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Detection of vitamin B12 deficiency in older people by measuring vitamin B12 or the active fraction of vitamin B12, holotranscobalamin.
- 2007
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In: Clinical Chemistry. - : Oxford University Press (OUP). - 0009-9147 .- 1530-8561. ; 53:5, s. 963-970
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Journal article (peer-reviewed)abstract
- 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). METHODS: We compared the utility of serum holoTC with conventional vitamin B(12) for detection of vitamin B(12) deficiency in a population-based study of older people, using increased methylmalonic acid (MMA) concentrations as a marker of metabolic vitamin B(12) deficiency in the overall population (n = 2403) and in subsets with normal (n = 1651) and abnormal (n = 752) renal function. RESULTS: Among all participants, 6% had definite (MMA >0.75 micromol/L) and 16% had probable (MMA >0.45 micromol/L) metabolic vitamin B(12) deficiency. In receiver operating characteristic curves for detection of definite vitamin B(12) deficiency, holoTC had a greater area under the curve (AUC) compared with vitamin B(12) in all participants (0.85 vs 0.76; P <0.001) and in subsets with normal (AUC: 0.87 vs 0.79; P <0.001) and abnormal (AUC: 0.85 vs 0.74; P = 0.002) renal function. Similar findings were observed for detection of moderate vitamin B(12) deficiency. Whereas the positive predictive value for both holoTC and vitamin B(12) was greater for detection of probable than definite vitamin B(12) deficiency, both tests were associated with more false-positive than true-positive test results. CONCLUSIONS: HoloTC has a modestly superior diagnostic accuracy compared with conventional vitamin B(12) for the detection of vitamin B(12) deficiency, but neither test can be recommended to screen asymptomatic populations.
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| 2. |
- Hin, Harold, et al.
(author)
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Clinical relevance of low serum vitamin B12 concentrations in older people : the Banbury B12 study
- 2006
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In: Age and Ageing. - London : Oxford University Press. - 0002-0729 .- 1468-2834. ; 35:4, s. 416-422
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Journal article (peer-reviewed)abstract
- 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. Participants: a total of 1,000 individuals aged 75 years or older living in the community. Results: low vitamin B12 concentrations were identified in 13% of older people and were associated with memory impairment and depression. After adjustment for age, sex and smoking, individuals with vitamin B12 or holotranscobalamin (holoTC) in the bottom compared with top quartiles had a 2-fold risk (OR = 2.17; 95% CI 1.11-4.27) and a 3-fold risk (OR = 3.02; 95% CI 1.31-6.98) of cognitive impairment, respectively. Low vitamin B12 status was also associated with missing ankle tendon jerks but not with depression. Treatment with vitamin B12 for 3 months corrected the biochemical abnormalities but had no effect on any of the clinical measurements. Conclusions: low vitamin B12 concentrations are associated with cognitive impairment and missing ankle tendon jerks in older people in the absence of anaemia. Large-scale trials of vitamin B12 supplementation are required to assess the clinical significance of these associations.
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| 3. |
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| 4. |
- Strand, Tor A, et al.
(author)
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Folate, but not vitamin B-12 status, predicts respiratory morbidity in north Indian children.
- 2007
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In: American Journal of Clinical Nutrition. - 0002-9165 .- 1938-3207. ; 86:1, s. 139-144
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Journal article (peer-reviewed)abstract
- BACKGROUND: Vitamin deficiencies are often part of malnutrition, which predisposes to acute lower respiratory tract infections. OBJECTIVE: The objective was to measure the association between cobalamin and folate status and subsequent respiratory morbidity. DESIGN: A prospective cohort study was conducted in 2482 children aged 6-30 mo nested in a zinc supplementation trial. We measured plasma concentrations of folate, cobalamin, methylmalonic acid, and total homocysteine (tHcy) and followed the children for 4 mo. RESULTS: We observed 1176 episodes of acute lower respiratory tract infections. Children with folate concentrations in the lowest quartile (interquartile range: 6.4-20.0 nmol/L) had a 44% higher incidence [adjusted incidence rate ratio (IRR): 1.44; 95% CI: 1.23, 1.70] of acute lower respiratory tract infections than did children in the other 3 quartiles. For tHcy, the IRR was 1.24 (1.07, 1.40) in a comparison of those in the highest quartile with those in the other quartiles. Breastfeeding was associated with high folate concentrations and protection against subsequent respiratory tract infections. This protection was significantly and substantially reduced after adjustment for plasma folate concentrations at baseline. Compared with the children in the other 3 quartiles, the IRR for being in the lowest quartile of cobalamin was 1.13 (0.76, 1.03) and for being in the highest quartile of methylmalonic acid was 1.12 (0.96, 1.31). CONCLUSIONS: Poor folate status appears to be an independent risk factor for lower respiratory tract infections in young children. This study also suggests that the protective effect of breastfeeding is partly mediated by folate provided through breast milk.
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