The Relationship between Intrinsic Factor and the Intestinal Absorption of Vitamin B<sub>12</sub>

Baker, S. J.; Mollin, D. L.

doi:10.1111/j.1365-2141.1955.tb05486.x

Cited by 63 publications

(20 citation statements)

References 10 publications

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“…These findings indicate great individual variation in the absorption gradient in patients with pernicious anemia for doses of vitamin B12 above the physiologic range. Such a variation in the absorption gradient is well known also for test doses of a more physiologic magnitude, when a source of intrinsic factor is added (23).…”

Section: Resultsmentioning

confidence: 99%

A Dual Mechanism of Vitamin B12 Plasma Absorption1

Doscherholmen¹,

Hagen²

1957

J. Clin. Invest.

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Recent reports have described two types of plasma absorption curves following the oral administration of vitamin B1.,. With microbiologic assay methods, after massive doses of vitamin. Bs, early significant plasma levels have been found indiscriminately in both pernicious anemia patients and control subjects (1, 2). On the other hand, two independent laboratories, using radio-labeled cyanocobalamin, have successfully determined plasma absorption curves after the oral administration of only 0.46 to 1.0 microgram doses (3, 4).With these small amounts of vitamin B12 a distinctly different type of absorption curve was found in normal subjects and in pernicious anemia patients when intrinsic factor was added. This curve was characterized by little or no plasma radioactivity during the first four hours of the test and a peak concentration in the 8-to 12-hour interval. Furthermore, there was clear differentiation between control subjects and patients with pernicious anemia, because at these dosage levels the latter without added intrinsic factor showed insignificant plasma radioactivity.In this investigation plasma absorption curves were obtained in pernicious anemia patients with and without intrinsic factor, as well as in control subjects after the oral administration of test doses of radio-labeled cyanocobalamin which ranged from 0.56 to 500 micrograms. This included a dosage range not previously examined. MATERIAL AND METHODSCobalt'-labeled vitamin B. 2 used in test doses had an initial specific activity of 1,137 microcuries per mg., while that of the Cotm-labeled vitamin Bn-2 used was 893 microcuries per mg. Crystalline non-radioactive vitamin B,2 was added as necessary to make up the desired test

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Section: Resultsmentioning

confidence: 99%

A Dual Mechanism of Vitamin B12 Plasma Absorption1

Doscherholmen¹,

Hagen²

1957

J. Clin. Invest.

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“…Decreased absorption of radioB12 is observed when a relatively large amount of cyanocobalamin is given parenterally before the oral administration of radioB12 (34,35). Although this phenomenon might be due to "saturation" of intramural intestinal receptors (36), it is possible that some of the parenterally administered cyanocobalamin is excreted into the intestine, where it could either exchange with bound radioB12 or be bound by any available IF.…”

Section: Discussionmentioning

confidence: 99%

Exchange Between Free and Gastric Juice-Bound Cyanocobalamin*

Donaldson¹,

Katz²

1963

J. Clin. Invest.

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“…The faecal excretion method (Heinle el at., 1952) was used in all cases. After at least three days without laxatives, vitamins or antibiotics, subjects were fasted overnight for at least ten hours, venous blood was withdrawn for serum vitamin-B12 assay (see below), and a deep subcutaneous injection of 0.25 mg carbamylcholinc chloride ("Carbachol") was given to stimulate the secretion of intrinsic factor (Baker and Mollin, 1955).…”

Section: Methodsmentioning

confidence: 99%

“…In the general population on average mixed diets, serum-B12 levels do not correlate with the amount of B12 absorbed (Weinstein and Watkin, 1958); but Baker and Mollin (1955) showed that B12 absorption is affected by the B12 content of the body, the relation being an inverse one. Once again we are up against the problem of the relation between tissue stores of B12 and the serum level.…”

Section: Figmentioning

confidence: 99%

The Absorption of Vitamin B<sub>12</sub> in the Elderly

De¹

1964

Geront clin

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The Relationship between Intrinsic Factor and the Intestinal Absorption of Vitamin B₁₂

Cited by 63 publications

References 10 publications

A Dual Mechanism of Vitamin B12 Plasma Absorption1

A Dual Mechanism of Vitamin B12 Plasma Absorption1

Exchange Between Free and Gastric Juice-Bound Cyanocobalamin*

The Absorption of Vitamin B<sub>12</sub> in the Elderly

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The Relationship between Intrinsic Factor and the Intestinal Absorption of Vitamin B12

Cited by 63 publications

References 10 publications

A Dual Mechanism of Vitamin B12 Plasma Absorption1

A Dual Mechanism of Vitamin B12 Plasma Absorption1

Exchange Between Free and Gastric Juice-Bound Cyanocobalamin*

The Absorption of Vitamin B<sub>12</sub> in the Elderly

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The Relationship between Intrinsic Factor and the Intestinal Absorption of Vitamin B₁₂