Diets during pregnancy associated with asthma risks at age 6 years
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Key takeaways:
- More whole eggs and baked goods and fewer carrots and processed meats were linked to more active asthma.
- There were no associations between microbial diversity and active asthma at age 6 years.
SAN DIEGO — Maternal diets were associated with risks for active asthma among children at age 6 years, according to a presentation at the American Thoracic Society International Conference.
“Asthma often presents early in life,” Lourdes G. Ramirez, MD, MS, fellow in allergy and clinical immunology, Brigham and Women’s Hospital, said during her presentation. “Its early onset indicates that prenatal and early life exposures play important roles in the development of asthma.”
Yet the roles of diet and other maternal factors are not well defined, she continued, adding that current guidelines for avoiding asthma and allergy among children only encourage pregnant mothers to include potentially allergenic foods in their diet.
“Dietary patterns from pregnancy have been postulated to affect fetal programming, the microbiome and the immune system, and it may be a potentially modifiable factor in allergy prevention,” Ramirez said.
Although previous research has indicated a link between maternal diet and childhood asthma, varied study designs make these conclusions difficult, Ramirez said.
“We also have some evidence that microbiome features are associated with offspring asthma phenotypes,” she added.
With an interest in whether dietary features act via the microbiome to modify risks for asthma in children, Ramirez and colleagues examined relationships between maternal diet and offspring asthma, between maternal diet during pregnancy and microbiome composition in mothers and offspring, and between microbiome composition and early offspring asthma.
The researchers used data from the Vitamin D Antenatal Asthma Reduction Trial, which investigated whether the use of vitamin D during pregnancy could prevent pediatric asthma.
Pregnant mothers (n = 881) completed questionnaires at enrollment and at 10 to 18 weeks of gestation about how frequently they ate 18 different foods. Also, 16S RNA profiling data were collected from maternal stool samples (n = 120) during each trimester.
Children were followed for more than 6 years, and caregivers completed quarterly questionnaires about asthma outcomes. Stool samples collected from the children were analyzed for 16S RNA at age 3 to 6 months (n = 265) and at age 1 year (n = 436) as well.
Of 707 mother-offspring pairs with complete maternal dietary and active asthma data, 133 (19%) children had active asthma and 574 (81%) did not.
Logic regression models indicated an association between a diet including high intake of vegetables and low intake of processed meats and deep-fried foods (PC1) and reduced active asthma at age 6 years (OR = 0.87; 95% CI, 0.76-0.99).
Also, high intake of whole eggs and baked products and low intake of carrots and processed meats (PC14) was associated with increased asthma (OR = 1.38; 95% CI, 1.07-1.79)
“Next, we tested the association between specific nutrient densities from completed questionnaires and active asthma at age 6 years, and we found significant associations between maternal consumption of animal fat and cholesterol and increased active asthma at age 6 years,” Ramirez said.
Odds ratios included 1.77 (95% CI, 1.04-3.1) for animal fat and 1.58 (95% CI, 1.02-2.46) for cholesterol.
Stool samples included 111 from mothers in the third trimester, with 21 children (19%) children with active asthma and 90 children (81%) who did not have active asthma; 237 children at age 3 to 6 months, including 44 (19%) with active asthma and 193 (81%) without active asthma; and 402 children at age 1 years, including 72 (18%) with active asthma and 330 (82%) who did not have active asthma.
“We tested associations between microbial composition and dietary features we found were associated with actual asthma, so PC1, PC14, cholesterol and animal fat,” Ramirez said.
The researchers analyzed microbial diversity at the genus level by alpha diversity, which measured diversity within each sample, and beta diversity, which measured taxonomic compositional dissimilarity between two samples.
“We used layer models to assess the association between the abundance of multiple microbial taxa in stool samples and maternal dietary intake,” Ramirez said.
There were no associations between PC1, PC14, cholesterol or animal fat in maternal diets and alpha diversity in the stool of the mothers or their offspring.
“However, PC1 was associated with beta diversity in the maternal stool, offspring 3- to 6-month stool and 1-year stool,” Ramirez said. “Animal fat was associated with beta diversity in the maternal stool, but not in the offspring stool.”
Also, there was no significant association between beta diversity and PC14 or cholesterol in any of the stools, Ramirez said.
Additional examination revealed positive associations between cholesterol intake and Eggerthella in stool at age 3 to 6 months as well as between PC14 and Clostridium sensu stricto 1 in stool at age 1 year.
But there were no statistically significant associations between alpha or beta diversity or any of the specific taxa in any of the stool samples and with active asthma at age 6 years, Ramirez said.
“This may be due to various limitations of our study, including unlimited sample size and the fact that we used 16 S RNA sequencing data as opposed to higher resolution sequencing,” Ramirez said. “It’s also possible that the diet-asthma association may be mediated by pathways other than the microbiome.”