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PUBLIC RELEASE DATE:
19-May-2014

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Contact: Nathaniel Dunford
ndunford@thoracic.org
American Thoracic Society
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Intake of dietary methyl donors in the first trimester affects asthma risk in children

ATS 2014, SAN DIEGO ─ Maternal intake of dietary methyl donors during the first trimester of pregnancy modulates the risk of developing childhood asthma at age 7, according to a new study presented at the 2014 American Thoracic Society International Conference.

"Evidence on the effects of dietary methyl donor intake on childhood asthma has been mixed," said lead author Michelle Trivedi, MD, Clinical Fellow in Pediatric Pulmonology at Massachusetts General Hospital for Children in Boston. "It has been suggested that folate enrichment of some foods may have contributed to the increasing asthma and allergy prevalence in the US. In our study of more than a one thousand mother-child pairs, we found that maternal intake of the six methyl donors we studied, folate, choline, betaine, and vitamins B2, B6, and B12, had protective effects on the risk of developing childhood asthma, and that interactions between these nutrients affected the magnitude and the direction of this risk."

Methyl donors are nutrients involved in a biochemical process called methylation, in which chemicals are linked to proteins, DNA, or other molecules in the body. This process is involved in a number of important functions in the body, and dietary intake of methyl donors has been shown to affect the risk of developing a number of diseases, including heart disease and cancer.

In the current study, maternal dietary and supplemental methyl donor intake was assessed with food-frequency questionnaires in the first and second trimesters in 1,052 mother-child pairs. Of the 1,052 children, 219 (20.8%) were diagnosed with asthma at age 7.

In analyses adjusting for age, body mass index, asthma, education, and household income of the mother along with the birth weight, sex, race/ethnicity, duration of breastfeeding, exposure to environmental tobacco smoke, and eczema of the child, only dietary vitamin B12 and choline in the first trimester were associated with lower asthma prevalence at age 7.

"Our results suggest that dietary intake of folate and other methyl donors during pregnancy does not increase the risk for asthma and may, in fact, decrease the risk of offspring developing asthma," said Dr. Trivedi. "Further study is warranted to dissect potential mechanisms."

Dr. Trivedi's group is planning further research on the mechanisms by which folate and other methyl donors affect the methylation status of DNA.

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* Please note that numbers in this release may differ slightly from those in the abstract. Many of these investigations are ongoing; the release represents the most up-to-date data available at press time.

Abstract 54675
Maternal Intake Of Dietary Methyl Donors In Pregnancy And Childhood Asthma At 7 Years
Type: Scientific Abstract
Category: 01.21 - Pediatric Epidemiology: Risk Factors, Outcomes and Management (PEDS)
Authors: M. Trivedi1, S. Sharma2, S. Rifas-Shiman3, C.A. Camargo4, S.T. Weiss5, M. Gillman3, D. Gold6, D.L. DeMeo7, A.A. Litonjua7; 1Massachusetts General Hospital -
Boston, MA/US, 2Channing Laboratory - Boston, MA/US, 3Harvard Pilgrim Health Care Institute - Boston, MA/US, 4Massachusetts General Hospital, Harvard Medical School - Boston, MA/US, 5Channing Laboratory, Brigham & Women's Hospital - Boston, MA/US, 6Harvard School of Public Health - Boston/US, 7Brigham and Women's Hospital - Boston, MA/US

Abstract Body

Rationale: Prenatal folate and other methyl donor intake are currently being evaluated as potential contributors to the development of childhood asthma. Existing studies have been variable, showing both positive and negative associations of dietary methyl donor intake with childhood asthma. This study seeks to look more comprehensively at the dietary intake of methyl donors during pregnancy and its association with the development of childhood asthma.

Methods: Subjects were 1052 mother-child pairs in Project Viva, an ongoing prospective cohort study. Maternal dietary and supplemental intake was assessed using validated food-frequency questionnaires administered in the first and second trimesters. The six nutrients assessed were folate, choline, betaine, and vitamins B2, B6, and B12, with and without supplementation. Because the distributions of the nutrients differed, z-scores were generated for each of the nutrients and used as the exposure of interest. The primary outcome was current physician-diagnosed asthma at age 7 years. We used multivariable logistic regression to adjust for age, BMI, asthma, education, and household income of the mother, as well as birth weight, sex, race/ethnicity, duration of breastfeeding, environmental tobacco smoke exposure, and eczema, of the child.

Results: Of the 1052 children, 219 (20.8%) were diagnosed with asthma, 715 (68.0%) were Caucasian, 143 (13.6%) were African American, 38 (3.6%) were Hispanic, 34 (3.2%) were Asian and 122 (11.6%) were other race/ethnicity. In the univariate models, higher intake of folate, choline, B2, and betaine were associated with lower asthma prevalence. However, in the adjusted models for each nutrient, only dietary choline and vitamin B12 (without supplementation) in the 1st trimester were associated with lower asthma prevalence. Considering that these nutrients are in the same one-carbon metabolism pathway, we created a single model combining all six nutrients together along with the other co-variates of interest. In this combined model, B6 (OR 1.52, 95%CI=1.04, 2.21) and dietary choline (OR 0.72, 95% CI=0.56, 0.93) were significantly associated with childhood asthma.

Conclusion: Our results suggest that maternal intake of dietary methyl donors in the 1st trimester of pregnancy may modulate the risk for childhood asthma. The change in direction and strength of effect of dietary intake of B6 when adjusting for other dietary methyl donors suggests that these nutrients interact with one another in modulating the risk for childhood asthma.

*Odds ratios are for each 1 standard deviation increase in nutrient intake.

Associations of Maternal Dietary Intake of Nutrients (Without Supplementation) During Pregnancy with Asthma Prevalence at 7years
Nutrient Unadjusted OR (95% CI)* Adjusted OR (95% CI)* Adjusted OR, All Nutrients Included (95% CI)*
1st Trimester

Folate 0.81 (0.67, 0.97) 0.88 (0.70, 1.11) 0.80 (0.57, 1.14)
Vitamin B2 0.77 (0.64, 0.93) 0.78 (0.61, 1.01) 0.79 (0.53, 1.18)
Vitamin B6 0.92 (0.77, 1.09) 0.97 (0.78, 1.21) 1.52 (1.04, 2.21)
Vitamin B12 0.99 (0.85, 1.16) 0.77 (0.61, 0.99) 0.87 (0.65, 1.18)
Betaine 0.81 (0.68, 0.97) 0.98 (0.77, 1.24) 1.04 (0.81, 1.35)
Choline 0.81 (0.69, 0.96) 0.70 (0.55, 0.89) 0.72 (0.56, 0.93)

2nd Trimester

Folate 0.87 (0.72, 1.04) 0.98 (0.76, 1.25) 1.04 (0.70, 1.54)
Vitamin B2 0.84 (0.70, 1.01) 0.92 (0.72, 1.17) 0.99 (0.68, 1.44)
Vitamin B6 0.88 (0.73, 1.05) 0.97 (0.75, 1.24) 1.08 (0.71, 1.64)
Vitamin B12 0.89 (0.73, 1.09) 0.86 (0.67, 1.11) 0.88 (0.64, 1.21)



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