How long does vitamin b12 last in your system

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Duration of Vitamin B12 in the Human System

Biological Half-life of Vitamin B12 in Plasma

The biological half-life of vitamin B12 in plasma is a critical factor in understanding how long it lasts in the human system. Research using kinetic analysis of isotope experiments with tracer doses of radioactive vitamin B12 has shown that the biological half-life of vitamin B12 in plasma is approximately 6 days . This finding was confirmed through different experimental methods, which calculated the half-life to be around 5.14 days .

Vitamin B12 Retention in the Body

The retention of vitamin B12 in the body varies depending on the form it is bound to. When vitamin B12 is bound to transcobalamin I, the plasma turnover shows a half-life of about 9-10 days . In contrast, when bound to transcobalamin II, the half-life is significantly shorter, approximately 1.5 hours, although the final plasma curves for both forms yield similar half-life values of around 9.3 to 9.8 days due to the rapid reappearance of the radiocobalt label bound to transcobalamin I .

Vitamin B12 Absorption and Age

Interestingly, the absorption of vitamin B12 from the gut does not decline with age in normal elderly humans. Studies have shown that whole body retention of vitamin B12 at 14 days in elderly subjects is comparable to that in younger individuals, indicating that age does not significantly affect vitamin B12 absorption .

Long-term Storage in the Liver

While the plasma half-life of vitamin B12 is relatively short, the liver can store vitamin B12 for much longer periods. The biological half-life of vitamin B12 in the liver averages about 12 months, which contrasts sharply with its plasma half-life . This long-term storage capability in the liver ensures that the body has a reserve of vitamin B12 that can be utilized over extended periods.

Conclusion

In summary, vitamin B12 has a plasma half-life of approximately 6 days, with variations depending on the binding form. The liver can store vitamin B12 for up to 12 months, providing a significant reserve. Age does not appear to affect the absorption of vitamin B12, ensuring consistent retention across different age groups. Understanding these dynamics is crucial for managing vitamin B12 levels in the body effectively.

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Most relevant research papers on this topic

Biological Half-life of Vitamin B12 in Plasma

The biological half-life of vitamin B12 in plasma is about 5.14 days, compared to about 12 months in the liver.

1963·

27citations

·J. Adams

Vitamin B12 absorption from the gut does not decline with age in normal elderly humans.

Vitamin B12 absorption does not decline with age in normal elderly humans.

Observational Study

1982·

27citations

·A. McEvoy et al.

PB2548: COMPARISON BETWEEN WEEKLY INTRAVENOUS VERSUS DAILY ORAL VITAMIN B12 SUPPLEMENTATION IN ANEMIA WITH VITAMIN B12 DEFICIENCY

Weekly intravenous vitamin B12 supplementation is more effective than daily oral vitamin B12 supplementation for treating anemia with vitamin B12 deficiency.

RCT

2023·

0citations

·K. Modak et al.

Applicability of Hydroxocobalamin as a Long-acting Vitamin B12

THE main difficulty in the treatment of vitamin B12 deficiencies has been that small doses of cyanocobalamin are inadequate to replenish the body's depleted stores and that most of the large parenteral doses are eliminated in the urine within the first 12 hr.

1961·

22citations

·G. B. J. Glass et al.

Plasma turnover of 57cobalt-vitamin B12 bound to transcobalamin I and II.

Radioactive vitamin B12 bound to transcobalamin I has a T 1/2 value of 9.3 and 9.8 days, while bound to transcobalamin II has a T 1/2 value of 1.5 hours.

In Vitro Study

2009·

42citations

·B. Hom

Stability of Folate and Vitamin B12 in Human Serum after Long-Term Storage: A Follow-Up after 13 Years

Folate concentrations in human serum remain stable at 80°C, while vitamin B12 concentrations decrease to about 50%, allowing for reliable comparative analyses even after 13 years.

Very Rigorous Journal

2018·

14citations

·E. Jansen et al.

Radioactive vitamin B12 absorption studies: results of direct measurement of radioactivity in the blood.

This method effectively measures vitamin B12 absorption in the blood or plasma, aiding in diagnosis of pernicious anemia and other malabsorptive states, and evaluating intrinsic factor activity.

1957·

37citations

·Alfred Doscherholmen et al.

Radioactive vitamin B12 absorption studies: comparison of the whole-body retention, urinary excretion, and eight-hour plasma levels of radioactive vitamin B12.

A proportional relationship exists between whole-body retention, 8-hour plasma radioactivity, and urinary excretion of radioactive vitamin B12.

Observational Study

1971·

13citations

·M. Cottrall et al.

Absorption of Vitamin B12 in Pernicious Anaemia: IV. Administration into Buccal Cavity, into Washed Segment of Intestine, or after Partial Sterilization of Bowel

Vitamin B12 administration into the buccal cavity, into a washed segment of the intestine, or after partial sterilization of the bowel can effectively improve pernicious anaemia and maintain reticulocyte levels.

1950·

7citations

·C. Ungley

Studies on the Transcobalamins

Vitamin B12 absorbed from the gut is transported on all transcobalamins, not primarily on Transcobalamin II, and can still be detected on these proteins after 10 days, suggesting that the rapid plasma clearance of TCII-vitamin B12 complex may be due to damage before re-injection.

1973·

28citations

·J. England et al.

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