Benefits and risks of folic acid to the nervous system.
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During three decades of neurological practice I have witnessed a remarkable change in attitudes to the benefits and risks of folic acid therapy in nervous system disorders. In the 1960s all that was known and taught was that folic acid was harmful to the nervous system, especially in precipitating or exacerbating the neurological complications of vitamin B12 deficiency. So deeply held was this view that the possibility of neuropsychological benefits from this vitamin was initially viewed with considerable scepticism. (+info)
Dietary vitamin B12 deficiency in an adolescent white boy.
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Dietary deficiency of cobalamin resulting in tissue deficiency in white individuals is unusual. However, several patients with dietary deficiency who were neither vegan nor Hindu have been described. This report describes the case of a 14 year old boy who was a white non-Hindu with a very low intake of cobalamin, which was not apparent until a detailed dietary assessment was performed. The patient responded rapidly to a combination of oral and parenteral B12. This case illustrates the fact that severe dietary vitamin B12 deficiency can occur in non-Hindu white individuals. Inadequate dietary content of B12 may not be apparent until a detailed dietary assessment is performed. This patient is likely to have had subclinical vitamin B12 deficiency for several years. Increased vitamin B12 requirements associated with the adolescent growth spurt may have provoked overt tissue deficiency. (+info)
Nature and nurture in vitamin B12 deficiency.
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We report on a child in whom severe nutritional vitamin B12 deficiency was exacerbated by a genetic impairment of the folate cycle, causing reduced CSF concentrations of the methyl group donor 5-methyltetrahydrofolate. Some patients with vitamin B12 deficiency may benefit from high dose folic acid supplementation, even if plasma concentrations are high. (+info)
Transcobalamin II 775G>C polymorphism and indices of vitamin B12 status in healthy older adults.
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A common polymorphism (775G>C) in the vitamin B12 transport protein, transcobalamin II (TCII), has been identified in which proline replaces arginine at codon 259. We determined the influence of TCII genotype on indices of B12 status, including total serum B12, the amount of B12 bound to TCII (holoTCII), methylmalonic acid, and homocysteine, in 128 healthy older adults (ages 40-88 years). Mean total B12 and homocysteine concentrations were not significantly different among the 3 genotypes. Mean holoTCII concentration was significantly higher in those subjects homozygous for the proline form of TCII (PP) compared with those homozygous for the arginine form (RR) and heterozygotes (PR) (P +info)
Low vitamin B-12 intake and status are more prevalent in Hispanic older adults of Caribbean origin than in neighborhood-matched non-Hispanic whites.
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Vitamin B-12 deficiency is a recognized problem among older adults, although vitamin B-12 status among differing ethnic groups remains unclear. We examined vitamin B-12 intake and status in a representative sample of elderly Hispanics of Caribbean origin (Puerto Rican and Dominican) and non-Hispanic whites. Dietary intake and plasma values were available for 347 Puerto Ricans, 102 Dominicans and 154 non-Hispanic whites (60-93 y). Relative to non-Hispanic whites, Hispanics had significantly lower vitamin B-12 intake and plasma concentrations; 17% of Hispanics and 10% of non-Hispanic whites had concentrations < 185 pmol/L (P < 0.05). Among Hispanics, log transformed vitamin B-12 intake was significantly associated with plasma concentration (beta = 60 pmol/L per log unit vitamin B-12 intake, P < 0.002 for supplement users and beta = 74 pmol/L per log unit vitamin B-12 intake, P < 0.01 for nonsupplement users). Intake and plasma concentrations were significantly associated among non-Hispanic whites only when supplement users were included (beta = 95 pmol/L per log unit vitamin B-12 intake, P < 0.0001). Hispanic supplement users (18%) had higher plasma concentrations than did nonsupplement users (364 +/- 17 and 297 +/- 8 pmol/L, respectively, P < 0.001). For Hispanics, consumption of breakfast cereal > 4 times/wk compared to no cereal was protective against lower plasma concentrations (8 vs. 24% < 185 pmol/L, P < 0.01). Approximately 40% of both groups with plasma vitamin B-12 < 185 pmol/L had homocysteine > 14 micromol/L, relative to < 17% of those with B-12 > 185 pmol/L. The high prevalence of low vitamin B-12 status in elderly Hispanics appears largely attributed to inadequate intake. As in other populations, sources of unbound vitamin B-12 such as supplements and fortified cereal appear to be protective. Dietary intervention programs targeted to the Hispanic population should promote these vitamin B-12 sources. (+info)
Elevated serum methylmalonic acid concentrations are common among elderly Americans.
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To describe serum methylmalonic acid (MMA) concentrations of elderly Americans and examine relationships between serum MMA and other factors, we used surplus serum samples collected from elderly (n = 1145) and young-adult (n = 1026) participants in Phase 2 of the third National Health and Nutrition Examination Survey (1991-1994). In approximately 20% of participants >/=65 y old, serum MMA was >370 nmol/L, the 90th percentile of the distribution of participants aged 30-39 y. Consistent with previous reports, we observed strong, independent positive associations between serum MMA concentration and serum concentrations of creatinine and homocysteine. After controlling for demographic factors and creatinine, geometric mean MMA concentration was lower in non-Hispanic blacks [223.6 nmol/L; 95% confidence interval (CI), 198.8-251.5] than non-Hispanic whites (265.1 nmol/L; 95% CI, 240.3-292.4). However, the prevalence of elevated levels did not vary with race/ethnicity. Serum MMA concentration bore a strong inverse relation to serum vitamin B-12 concentration. Nevertheless, elevated serum MMA concentrations affected approximately 15% of those with both normal serum creatinine concentrations and serum B-12 concentrations >148 pmol/L. We conclude that many elderly Americans demonstrate metabolic evidence of low B-12 status, that elevations occur frequently in the absence of traditional deficiency indicators and that levels vary with race/ethnicity and renal function. (+info)
Dental implications of Helicobacter pylori.
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Helicobacter pylori infections of the stomach are common worldwide and may cause serious medical problems, ranging from gastritis and its sequelae to gastric carcinoma or lymphoma. Current studies indicate that H. pylori is present in dental plaque, although the number of organisms in individual samples is very low, and these numbers appear to vary from one site to another within the mouth. The presence of this organism in plaque may be intermittent, perhaps occurring as the result of gastroesophageal reflux. It is still unclear if the low numbers of H. pylori present in the mouths of most patients would be sufficient to serve as a source of infection or reinfection for gastric conditions. Whether dental plaque is a significant source for reinfection of the gastric mucosa among patients with fair to poor oral hygiene remains to be confirmed. It has been suggested that attempting to improve oral hygiene through standard periodontal procedures would be prudent as an ancillary measure to conventional ulcer therapy, especially in patients whose gastric infections have proven recalcitrant. H. pylori may also be a cofactor in the recurrence of aphthous ulceration, especially in patients sensitized through gastric colonization and mucosal attachment. (+info)
Decreased GFAP-mRNA expression in spinal cord of cobalamin-deficient rats.
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We have demonstrated previously that chronic vitamin B12 [cobalamin (Cbl)] deficiency preferentially affects glial cells in the rat central nervous system (CNS) and severely affects peripheral glial cells independently of and concomitantly with the central neuropathy. In this study, we determined the mRNA levels for myelin basic protein (MBP) and glial fibrillary acidic protein (GFAP) in different CNS areas of rats made Cbl-deficient by total gastrectomy, as well as the mRNA levels for glycoprotein Po and peripheral myelin protein (PMP)22 in the sciatic nerve. GFAP-mRNA levels were significantly decreased in the spinal cord (SC) and hypothalamus, but not in the cortex, hippocampus, or striatum of totally gastrectomized (TGX) rats. No differences in GFAP protein levels were found in the SC and hypothalamus of the TGX rats treated or not with Cbl. MBP-mRNA levels were significantly decreased only in the hypothalamus, and the levels of mRNA for both glial markers returned to normal with Cbl replacement therapy. The levels of mRNA for the various myelin proteins in the sciatic nerve were not modified by Cbl deficiency. These results demonstrate that: a) the neurotrophic action of Cbl in rat CNS occurs in a zonal manner; and b) Cbl deficiency does not affect myelin synthesis (with the sole exception of the hypothalamus). (+info)