vitamin-b-12 and Asthma

Studies of the effect of vitamin B12 and folate on the risk of asthma and hay fever have shown inconsistent results that may be biased by reverse causation and confounding. We used a Mendelian randomization approach to examine a potential causal effect of vitamin B12 and folate on hay fever, asthma, and selected biomarkers of allergy by using 11 vitamin B12-associated single-nucleotide polymorphisms (SNPs) and 2 folate-associated SNPs as unconfounded markers.. We included 162,736 participants from 9 population-based studies including the UK Biobank. Results were combined in instrumental variable and meta-analyses and effects expressed as odds ratios (ORs) or estimates with 95% confidence interval (CI).. Using genetic proxies for B12 and folate, instrumental variable analyses did not show evidence for associations between serum B12 and hay fever: OR = 1.02 (95% CI: 0.98, 1.05), asthma: OR = 0.99 (95% CI: 0.95, 1.04), allergic sensitization: OR = 1.02 (95% CI: 0.74, 1.40), or change in serum IgE: 10.0% (95% CI: -9.6%, 29.6%) per 100 pg/ml B12. Similarly, there was no evidence for association between serum folate and hay fever: OR = 0.74 (95% CI: 0.45, 1.21), asthma: OR = 0.80 (95% CI: 0.43, 1.49), or allergic sensitization: OR = 1.92 (95% CI: 0.11, 33.45), but there was a statistically significant association with change in serum IgE: 2.0% (95% CI: 0.43%, 3.58%) per 0.1 ng/ml serum folate.. Our results did not support the hypothesis that levels of vitamin B12 and folate are causally related to hay fever, asthma, or biomarkers of allergy, but we found evidence of a positive association between serum folate and serum total IgE.

Topics: Adult; Asthma; Female; Folic Acid; Genotype; Humans; Immunoglobulin E; Male; Mendelian Randomization Analysis; Middle Aged; Odds Ratio; Polymorphism, Single Nucleotide; Rhinitis, Allergic, Seasonal; Vitamin B 12

To assess the associations of folate, homocysteine and vitamin B12 levels of children at birth and their methylenetetrahydrofolate reductase (MTHFR) variants with asthma and eczema in childhood.. This study was embedded in a population-based prospective cohort study (n = 2,001). Neonatal cord blood folate, homocysteine and vitamin B12 levels were measured, and MTHFR C677T and A1298C genotyped. Wheezing and physician-diagnosed eczema were annually obtained by questionnaire until 4 years. At 6 years, we collected information on physician-diagnosed asthma ever and self-reported eczema ever, measured fractional exhaled nitric oxide (FeNO), and interrupter resistance (Rint). Data were analysed with generalized estimating equations or logistic regression: continuous outcomes with linear regression models.. Folate, homocysteine and vitamin B12 levels of children at birth were not associated with wheezing or eczema until 4 years, asthma and eczema ever, or FeNO or Rint at 6 years. In children carrying C677T mutations in MTHFR, higher folate levels were associated with an increased risk of eczema (repeated eczema until 4 years: OR 1.40 (95% CI 1.09-1.80) (SD change) P-interaction = 0.003, eczema ever at 6 years: OR 1.41 (0.97-2.03) P-interaction = 0.011). No interactions between MTHFR and child folate and homocysteine levels were observed for wheezing and asthma.. Folate, homocysteine and vitamin B12 levels of children at birth did not affect asthma- and eczema-related outcomes up to the age of 6 years. Further studies are warranted to establish the role of MTHFR variants in these associations.

Topics: Asthma; Biomarkers; Child; Child, Preschool; Dermatitis, Atopic; Female; Fetal Blood; Folic Acid; Follow-Up Studies; Genetic Markers; Genotype; Homocysteine; Humans; Infant; Infant, Newborn; Linear Models; Logistic Models; Male; Methylenetetrahydrofolate Reductase (NADPH2); Polymorphism, Single Nucleotide; Prospective Studies; Surveys and Questionnaires; Vitamin B 12

Topics: Aged; Asthma; Blindness, Cortical; Electroretinography; Female; Fluorescein Angiography; Humans; Hypoxia; Magnetic Resonance Imaging; Scotoma; Tomography, Emission-Computed, Single-Photon; Visual Acuity; Visual Fields; Vitamin B 12

Recent studies suggested low serum folate and impaired folate metabolism as potential risk factors for development of asthma and atopic disease, but the results are inconsistent. The aim of this study was to investigate the relations of markers of folate and vitamin B₁₂ (B₁₂) deficiency with different phenotypes of asthma and atopy.. A random sample of 6784 persons from a general population aged 30-60 years participated in a health examination in 1999-2001, and 4516 (66.6%) of those also participated in a follow-up examination 5 years later. The examinations included spirometry, measurements of serum folate and B₁₂, specific IgE to inhalant allergens, total IgE, and genotyping of the MTHFR-C677T polymorphism - a genetic marker of impaired folate metabolism. Information about dietary intake of folate and B₁₂, asthma diagnosis, and airway symptoms was obtained by questionnaires.. Low serum folate levels and the TT genotype of the MTHFR-C677T polymorphism were associated with increased prevalence of self-reported doctor-diagnosed asthma [odds ratio (OR) 1.37, 95% confidence interval (CI) 1.05-1.79 and OR 1.52; 95% CI 1.12-2.06, respectively] and attacks of shortness of breath (OR 1.43, 95% CI 1.14-1.79 and OR 1.47; 95% CI: 1.14-1.91, respectively). We found no significant associations with lung function or atopic outcomes. Serum levels of B₁₂ and dietary intake of folate and B₁₂ were not associated with asthma or atopy.. We found that two objective markers of folate deficiency were associated with self-reported doctor-diagnosed asthma and attacks of shortness of breath, but not with lung function or atopy.

Topics: Adult; Asthma; Cross-Sectional Studies; Diet; Enzyme-Linked Immunosorbent Assay; Female; Folic Acid; Genetic Predisposition to Disease; Genotype; Humans; Hypersensitivity, Immediate; Male; Methylenetetrahydrofolate Reductase (NADPH2); Middle Aged; Polymorphism, Single Nucleotide; Respiratory Function Tests; Vitamin B 12

Sulfites have been implicated as the cause of bronchospasm in some subjects with asthma. However, there is still no universally accepted explanation of the pathogenesis of these reactions. We have studied five children with asthma with metabisulfite intolerance confirmed by oral challenge testing. The challenge test with metabisulfite was repeated after premedication of all the patients with 1.5 mg of oral cyanocobalamin. In four of the five patients treated with cyanocobalamin, bronchospasm did not develop in the second metabisulfite challenge. The possible mechanisms are discussed.

Topics: Administration, Oral; Adolescent; Asthma; Bronchial Spasm; Child; Child, Preschool; Dose-Response Relationship, Drug; Drug Evaluation; Drug Tolerance; Humans; Male; Single-Blind Method; Sulfites; Time Factors; Vitamin B 12

Topics: Adolescent; Adult; Aged; Antigen-Antibody Reactions; Asthma; Child; Child, Preschool; Dermatitis, Atopic; Humans; Hydroxocobalamin; Hypersensitivity; Infant; Infant, Newborn; Middle Aged; Vitamin B 12

Topics: Adult; Asthma; Female; Humans; Male; Middle Aged; Staphylococcal Infections; Streptococcal Infections; Vitamin B 12

Topics: Asthma; Corrinoids; Hematinics; Humans; Vitamin B 12

Topics: Adrenal Cortex; Asthma; Corrinoids; Emergency Treatment; Hematinics; Humans; Vitamin B 12; Vitamins

Topics: Asthma; Corrinoids; Hematinics; Humans; Vitamin B 12; Vitamin B Complex

Topics: Asthma; Corrinoids; Hematinics; Humans; Vitamin B 12; Vitamin B Complex