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 | |
| State | Published - Jan 1 2012 |
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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)
Cite this
Vitamin B12 : Physiology, Dietary Sources, and Requirements. / Green, Ralph.
Encyclopedia of Human Nutrition. Vol. 4-4 Elsevier Inc., 2012. p. 351-356.Research output: Chapter in Book/Report/Conference proceeding › Chapter
}
TY - CHAP
T1 - Vitamin B12
T2 - Physiology, Dietary Sources, and Requirements
AU - Green, Ralph
PY - 2012/1/1
Y1 - 2012/1/1
N2 - 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.
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
UR - http://www.scopus.com/inward/record.url?scp=85043275864&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85043275864&partnerID=8YFLogxK
U2 - 10.1016/B978-0-12-375083-9.00056-8
DO - 10.1016/B978-0-12-375083-9.00056-8
M3 - Chapter
SN - 9780123750839
VL - 4-4
SP - 351
EP - 356
BT - Encyclopedia of Human Nutrition
PB - Elsevier Inc.
ER -