Evidence Concerning the Human Requirement for Vitamin B12

Bozian, Richard C.; Ferguson, John L.; Heyssel, Robert M.; Meneely, George R.; Darby, William J.

doi:10.1093/ajcn/12.2.117

Cited by 29 publications

(9 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Estimates were based on measurements in healthy subjects [11,16,22,23,24], subjects with low serum concentrations of vitamin B12 [23] and PA patients [11,16]. Absolute amounts of vitamin B12 lost per day varied in these subpopulations, but the rate of loss was a fixed percentage of the total body store of vitamin B12, regardless of the store size: the larger the body store, the larger the losses [16,24]. Across studies, the rate of loss varied from 0.04 (SD not available) to 0.17% per day (SD = 0.017).…”

Section: Resultsmentioning

confidence: 99%

“…The underlying assumption is that labeled vitamin B12 is distributed throughout the body in a manner similar to nonlabeled vitamin B12. We did not merely extract estimates based on measurements in healthy subjects [11,16,22,23,24] but also on subjects with low serum concentrations of vitamin B12 [23] and patients with pernicious anemia (PA) [11,16], because it appeared that the rate of loss does not significantly differ between these subpopulations [11,16,23]. One study reported the absolute mean loss of vitamin B12 per day and the total body content of vitamin B12 [24].…”

Section: Methodsmentioning

confidence: 99%

“…When no SD was provided, we estimated it based on individual subject data {SD = √[∑(x i - x mean 2 )/(N - 1)]} [8,10,11,16,22,23,30], on the standard error (SE: SD = SE * √n) [25,26,31] or we approximated it by the total range (SD ≈ 0.25 * total range) [11,25,32,33]. …”

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Systematic Review on Daily Vitamin B12 Losses and Bioavailability for Deriving Recommendations on Vitamin B12 Intake with the Factorial Approach

et al. 2013

View full text Add to dashboard Cite

Aims: To systematically review the literature on daily losses and bioavailability of vitamin B12. These estimates could be used for deriving recommendations on vitamin B12 intake for adults and elderly. Methods: We identified publications on daily vitamin B12 losses (July 2011) and publications on the bioavailability of vitamin B12 from foods or diets (June 2010) in MEDLINE, EMBASE and the Cochrane Library. Results: A pooled analysis of five studies (52 subjects) showed that 0.13 ± 0.03% of the total body store is lost per day. Absorption of vitamin B12 ranged from 4.5 (dose of 38 µg from consumption of liver) to 83% (dose of 3.0 µg from consumption of mutton meat). Data from eight studies including 83 subjects suggested that the amount of vitamin B12 absorbed from food (A_i) increased with increasing doses of vitamin B12 (D_i) as described by the equation: ln(A_i) = 0.7694 * ln(D_i) - 0.9614. Conclusion: Daily vitamin B12 losses in apparently healthy adults and elderly probably range from 1.4 to 5.1 µg. Vitamin B12 intakes needed to compensate for these losses seem to range from 3.8 to 20.7 µg. More evidence is needed on the relationships between biochemical markers of vitamin B12 status, vitamin B12 body store and long-term health outcomes to evaluate whether current recommendations on vitamin B12 intake (1.4-3 µg) need to be changed.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Systematic Review on Daily Vitamin B12 Losses and Bioavailability for Deriving Recommendations on Vitamin B12 Intake with the Factorial Approach

et al. 2013

View full text Add to dashboard Cite

show abstract

“…Assuming that, on the average, 40% of a single dose of 100 00Opg is retained by most normal children, and that the requirements during infancy and the pre-school years are of the order of 300 pg day-' child-' (World Health Organization, 1967), the retained amount, if completely utilized, will suffice for approximately 130 days or 19 weeks. This is probably an unwarranted and optimistic estimate, for body stores of vitamins decline in logarithmic rather than arithmetic fashion (Bozian, Ferguson, Heyssel, Meneely & Darby, 1963). The duration of protection of such a load must therefore be considerably shorter than 130 days.…”

Section: Discussionmentioning

confidence: 99%

Retention of a Single Oral Massive Dose of Vitamin A

Pereira

Begum

1973

Clinical Science

View full text Add to dashboard Cite

show abstract

“…These giant cells have a high RNA/DNA ratio (7,26). Defective DNA synthesis in the megaloblastic state has been reviewed (30,40).…”

mentioning

confidence: 99%

DNA flow cytometry of control Euglena and cell cycle blockade of vitamin B12‐starved cells

Lefort‐Tran¹,

Bré²,

Pouphile³

et al. 1987

Cytometry

View full text Add to dashboard Cite

Vitamin B E starvation inIn severe anaemia that is due to B12 avitaminosis, the block of mitosis and the maturation of the erythrocyte line is followed by a diminution of red blood cells, while large cells with abnormal nuclei ~fmegaloblasts") appear in the blood and the bone marrow. These giant cells have a high RNA/DNA ratio (7,26). Defective DNA synthesis in the megaloblastic state has been reviewed (30,40). In vitamin B12-deprived Euglena cells, divisions slow down and then stop, while RNA and protein content, number of chloroplasts, and mitochondria continue to increase (14). For the study of biological and biochemical disorders induced by vitamin B12 deficiency, Euglena cells, whose alterations resemble those observed in the megaloblasts, are a very suitable model for observing where "DNA replication cycle" is decoupled from the "growth cycle" (36), as they are easy to cultivate and even to synchronize. In the recovering cells, after addition of vitamin B12, the DNA replication is completed, followed by cell divisions (9). Two relatively synchronous divisions occur immediately without a new G1 phase (15,32,41).In the model of the metabolic cell cycle block, biochemical analyses have given a mean DNA content of 1.8 or twice that of G1 cells (5,161, with no information on cell heterogeneity. In contrast, microcytofluorometry or flow cytometric analyses can provide data on DNA content of individual cells. These two types of analysis complement each other and can lead to a better understanding of the cell cycle arrest, in light of independent results concerning the dispersed structure of chromatin in starved giant cells (4,6,12), the modification of histones (101, and the nucleosomal organization in control and vitamin B12-starved chromatin (241, all of which could affect DNA stainability.The fluorochrome Hoechst 33258 for DNA labeling was chosen in present studies in order to avoid, as far as possible, nonstoichiometric DNA stainability owing to differences in the conformation of the chromatin (23).Initial studies that used microfluorometry contributed to a better knowledge of the material because individual cells could be observed, and so, for example, mitotic cells could be distinguished from cells in GB. Later, flow cytofluorometric measurements allowed analysis of large samples, and thus statistically more reliable results could be obtained. The data indicated that starved Euglena cells were distributed in the S and G2 phases. No cells were found either in the G1 phase or in the M phase. The unbalanced growth of vitamin B12-deficient cells was characterized by a block in the DNA replication and another block at the transition from G2 to M.The significance of cell arrest is discussed in relation to DNA replication. MATERIALS AM) METHODSControl Cells Euglena gracilis strain Z (Cambridge culture collection No. 1224-5D) were cultivated, either on a mineral

show abstract

Evidence Concerning the Human Requirement for Vitamin B12

Cited by 29 publications

References 17 publications

Systematic Review on Daily Vitamin B12 Losses and Bioavailability for Deriving Recommendations on Vitamin B12 Intake with the Factorial Approach

Systematic Review on Daily Vitamin B12 Losses and Bioavailability for Deriving Recommendations on Vitamin B12 Intake with the Factorial Approach

Retention of a Single Oral Massive Dose of Vitamin A

DNA flow cytometry of control Euglena and cell cycle blockade of vitamin B12‐starved cells

Contact Info

Product

Resources

About