Vitamin B12: Physiology, Dietary Sources, and Requirements

Ralph Green

doi:10.1016/B978-0-12-375083-9.00056-8

Vitamin B12: Physiology, Dietary Sources, and Requirements

Ralph Green

Pathology and Laboratory Medicine

Research output: Chapter in Book/Report/Conference proceeding › Chapter

3 Scopus citations

Abstract

Vitamin B₁₂, a cobalamin, is required for only two enzyme reactions in humans and animals: The conversion of methylmalonyl CoA to succinyl CoA and addition of a methyl group to homocysteine to form methionine. Vitamin B₁₂ does not occur in plants, and the only natural sources are animal source foods, a low intake of which can cause deficiency. Vitamin B₁₂ release from food and its subsequent absorption are complex processes, which can be impaired by many factors leading to depletion of body stores over time. Several laboratory tests can be used to assess vitamin B₁₂ status but the mechanisms underlying the neurological and cognitive symptoms of deficiency are not yet understood.

Original language	English (US)
Title of host publication	Encyclopedia of Human Nutrition
Publisher	Elsevier Inc.
Pages	351-356
Number of pages	6
Volume	4-4
ISBN (Electronic)	9780123848857
ISBN (Print)	9780123750839
DOIs	https://doi.org/10.1016/B978-0-12-375083-9.00056-8
State	Published - Jan 1 2012

Keywords

Anemia
Cobalamin
DNA
Folate
Haptocorrin
Homocysteine
Intrinsic factor
Macrocytosis
Megaloblastic anemia
Methionine
Methylmalonic acid
Myelin
S-adenosyl methionine
Transcobalamin
Vitamin B

ASJC Scopus subject areas

Medicine(all)

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10.1016/B978-0-12-375083-9.00056-8

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abstract = "Vitamin B12, a cobalamin, is required for only two enzyme reactions in humans and animals: The conversion of methylmalonyl CoA to succinyl CoA and addition of a methyl group to homocysteine to form methionine. Vitamin B12 does not occur in plants, and the only natural sources are animal source foods, a low intake of which can cause deficiency. Vitamin B12 release from food and its subsequent absorption are complex processes, which can be impaired by many factors leading to depletion of body stores over time. Several laboratory tests can be used to assess vitamin B12 status but the mechanisms underlying the neurological and cognitive symptoms of deficiency are not yet understood.",

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AB - Vitamin B12, a cobalamin, is required for only two enzyme reactions in humans and animals: The conversion of methylmalonyl CoA to succinyl CoA and addition of a methyl group to homocysteine to form methionine. Vitamin B12 does not occur in plants, and the only natural sources are animal source foods, a low intake of which can cause deficiency. Vitamin B12 release from food and its subsequent absorption are complex processes, which can be impaired by many factors leading to depletion of body stores over time. Several laboratory tests can be used to assess vitamin B12 status but the mechanisms underlying the neurological and cognitive symptoms of deficiency are not yet understood.

KW - Anemia

KW - Cobalamin

KW - DNA

KW - Folate

KW - Haptocorrin

KW - Homocysteine

KW - Intrinsic factor

KW - Macrocytosis

KW - Megaloblastic anemia

KW - Methionine

KW - Methylmalonic acid

KW - Myelin

KW - S-adenosyl methionine

KW - Transcobalamin

KW - Vitamin B

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ER -

Vitamin B12: Physiology, Dietary Sources, and Requirements

Abstract

Keywords

ASJC Scopus subject areas

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