| Abstract | BACKGROUND: S-Adenosylmethionine (SAM)-dependent methylation reactions produce S-adenosylhomocysteine (SAH), the precursor of homocysteine, which has been associated with adverse events when it is elevated. OBJECTIVE: We studied a cohort of elderly with a high prevalence of cobalamin deficiency to determine whether SAH, SAM, or their ratio was abnormal; whether they correlated with other markers of vitamin deficiency; and whether they changed with cobalamin therapy. DESIGN: A convenience sample of elderly attending nutrition centers was enrolled for baseline demographic, biochemical, and nutritional assessments. Methylmalonic acid (MMA), total homocysteine, and other metabolites were measured by using gas chromatography-mass spectrometry. Serum SAM and SAH were measured by using stable-isotope-dilution liquid chromatography-mass spectrometry. Subjects found to have elevated serum MMA were treated with oral cyanocobalamin tablets (1000 microg/d) for 3 mo. Subjects with normal MMA were randomly assigned to 1 of 3 dosage groups: 0, 25, or 100 microg cyanocobalamin/d. RESULTS: The 149 elderly subjects had a mean age of 76.3 y; 81% were female, and 30% were African American. Serum MMA concentrations were elevated in 30% and SAH concentrations were elevated in 64% of the cohort. Those with elevated MMA concentrations had higher SAH and SAM concentrations. High-dose oral cobalamin lowered SAH, MMA, and total homocysteine concentrations significantly, although subjects with creatinine concentrations >109 umol/L had higher posttreatment SAH than did those with lower creatinine. CONCLUSIONS: Elevated serum SAH concentrations are common in elderly and are strongly influenced by both renal status and cobalamin deficiency. These elevated concentrations can be lowered with high-dose oral cobalamin therapy. |
| Authors | Sally P Stabler, Robert H Allen, Evi T Dolce, Mary Ann Johnson
(Affiliation: Department of Medicine, University of Colorado Health Sciences Center, Denver, CO, USA. sally.stabler at UCHSC.edu)
|
| Journal | The American journal of clinical nutrition
(Am J Clin Nutr)
Vol. 84
Issue 6
Pg. 1422-9
(Dec 2006)
ISSN: 0002-9165 United States |
| PMID | 17158426
(Publication Type: Journal Article, Randomized Controlled Trial, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S.)
|
| Chemical References |
- Vitamin B Complex
- S-Adenosylmethionine
- Vitamin B 12
- S-Adenosylhomocysteine
|
| Topics |
- Aged
- Aged, 80 and over
- Analysis of Variance
- Cohort Studies
- Dose-Response Relationship, Drug
- Double-Blind Method
- Female
- Gas Chromatography-Mass Spectrometry
(methods)
- Humans
- Kidney
(metabolism)
- Linear Models
- Male
- Middle Aged
- Nutrition Assessment
- S-Adenosylhomocysteine
(blood)
- S-Adenosylmethionine
(blood)
- Treatment Outcome
- Vitamin B 12
(therapeutic use)
- Vitamin B 12 Deficiency
(blood, drug therapy)
- Vitamin B Complex
(therapeutic use)
|
