Malabsorption of protein bound vitamin B12.

Dawson, D W; Sawers, Alistair; Sharma, Rinku

doi:10.1136/bmj.288.6418.675

Cited by 67 publications

(22 citation statements)

References 17 publications

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“…The low serum vitamin B,, may return to normal with treatment of the Fe deficiency alone (Cox et al 1959). Malabsorption of protein-bound vitamin B,, has been reported in chronic Fe deficiency (Dawson et al 1984). There was haematological evidence of Fe deficiency in 34% of our patients.…”

Section: Discussionmentioning

confidence: 48%

“…We do not advocate this approach, since neurological damage can occur in the absence of anaemia. The demonstration of malabsorption of protein-bound vitamin B,, in subjects with a low serum vitamin B,, level indicates that low vitamin B,, results should not be too readily discounted (Dawson et al 1984). Indeed, it has been argued that the lower limit of normal for serum vitamin B,, may be too low, since factors such as smoking can increase requirements (Smith, 1960).…”

Section: Discussionmentioning

confidence: 99%

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Masked vitamin B₁₂ and folate deficiency in the elderly

1985

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1. A high incidence of vitamin B,, or folate deficiency, or both, may be found in the elderly, particularly those in hospital. This report concerns fifty cases detected in an inner-city-area geriatric unit during the course of routine clinical investigation. The majority had none of the classical haematological signs of vitamin B,, or folate deficiency, and all the patients reported had a mean corpuscular volume (MCV) of less than 100 fl.2. There was a significant negative correlation between the MCV and the erythrocyte folate (P< 0.01), supporting earlier published work using a low serum folate as an index of folate deficiency.3. There was no correlation between the MCV and the serum vitamin B,,. Published work differs on this point. 4.Serum iron, total Fe-binding capacity and percentage Fe saturation results were available in forty patients in this series. There was a significant positive correlation between the serum Fe and the MCV (P

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Section: Discussionmentioning

confidence: 48%

Section: Discussionmentioning

confidence: 99%

Masked vitamin B₁₂ and folate deficiency in the elderly

1985

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“…Krasinski et al 1986). Crystalline vitamin B-12 absorption is normal in most people with atrophic gastritis, because intrinsic factor is not lowered to a critical degree (Dawson et al 1984, Doscherholmen et al 1976and 1981, Jones et al 1987, King et al 1979, Suter et al 1993. It is not known how efficient the absorption of vitamin B-12 from milk or fortified bread would be in elderly subjects with atrophic gastritis; however, it has been presumed that vitamin B-12 bioavailability from a fortified cereal product would be as high as that from a dietary supplement in subjects with atrophic gastritis, because crystalline vitamin B-12 is sprayed onto such products.…”

Section: Cyanocobalaminmentioning

confidence: 99%

Older Men and Women Efficiently Absorb Vitamin B-12 from Milk and Fortified Bread

Russell

Baik

Kehayias

2001

The Journal of Nutrition

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Nothing is directly known about the bioavailability of vitamin B-12 from dairy products or fortified grain products. We directly studied vitamin B-12 absorption from water, milk and fortified bread in adult subjects using 58 Co-labeled vitamin B-12 and a whole body gamma-ray counter/spectrophotometer. Sixteen healthy men and women over the age of 60 y with normal serum levels of vitamin B-12 and normal basal gastric acid secretion were studied.

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“…In general, a low total plasma B 12 level predicts for a low level of plasma holoTC 11. However, in 34 of 152 cancer patients (22%) included in our study, an abnormal depression in plasma holoTC I1 levels occurred in spite of total plasma B 12 levels in the normal range ( [4][5][6] showing treatment-related lowering of holo-TC I1 levels to the abnormal range in the presence of normal total plasma B 12 levels in patients receiving enterocyte-damaging therapy. Others have demonstrated similar malabsorption of B12 due to irradiation of the small bowel [ 3 8 4 0 ] and in association with the administration of chemotherapy [41,42].…”

Section: Discussionmentioning

confidence: 47%

New assay for the rapid determination of plasma holotranscobalamin II levels: Preliminary evaluation in cancer patients

Amin

Ramos

et al. 1993

American J Hematol

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We describe a new and rapid assay for the measurement of plasma B12 bound to transcobalamin II (holotranscobalamin II) using the property of adsorption of the polypeptides of apotranscobalamin II and holotranscobalamin II to the hydrophobic surface of microfine glass particles. Acid-washed microfine glass was used to separate vitamin B12 bound to the glycoproteins transcobalamin I and transcobalamin III (haptocorrin or R binder) from that bound to transcobalamin II. Sephadex gel filtration separation of 57Co-labelled vitamin B12 binders confirmed that > 90% of holotranscobalamin II can be removed from plasma holohaptocorrin by adsorption to microfine glass particles. Since only holotranscobalamin II is capable of delivering vitamin B12 to metabolizing cells, plasma holotranscobalamin II content reflects the availability of B12 to cells. Use of this test in cancer patients undergoing either chemotherapy or radiation therapy revealed evidence of early negative B12 balance that in some instances was induced by the treatment itself.

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Malabsorption of protein bound vitamin B12.

Cited by 67 publications

References 17 publications

Masked vitamin B₁₂ and folate deficiency in the elderly

Masked vitamin B₁₂ and folate deficiency in the elderly

Older Men and Women Efficiently Absorb Vitamin B-12 from Milk and Fortified Bread

New assay for the rapid determination of plasma holotranscobalamin II levels: Preliminary evaluation in cancer patients

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Malabsorption of protein bound vitamin B12.

Cited by 67 publications

References 17 publications

Masked vitamin B12 and folate deficiency in the elderly

Masked vitamin B12 and folate deficiency in the elderly

Older Men and Women Efficiently Absorb Vitamin B-12 from Milk and Fortified Bread

New assay for the rapid determination of plasma holotranscobalamin II levels: Preliminary evaluation in cancer patients

Contact Info

Product

Resources

About

Masked vitamin B₁₂ and folate deficiency in the elderly

Masked vitamin B₁₂ and folate deficiency in the elderly