Researchers have identified an epigenetic mechanism by which fiber in the diet of pregnant mice has a protective effect against the development of asthma in their offspring. A survey of 40 pregnant women also found that increased dietary fiber was associated with fewer visits to the doctor for respiratory problems during the first year of their child’s infancy. The Nature Communications study suggests that acetate, produced by the mother’s gut bacteria during digestion of fiber, caused epigenetic changes in the mouse fetuses that resulted in reduced allergic responses and decreased asthma after birth. The pregnant women surveyed also had increased levels of acetate in their blood.
Dr. Karen Freedle, Assistant Professor of Pediatrics, Emory University School of Medicine (webpage):
Expertise: pediatric immunology, specializing in the treatment of asthma, allergic rhinitis, atopic dermatitis (eczema), food allergy, eosinophilic diseases and mast cell diseases.
“Asthma induced by allergens (atopic asthma) is one of most common chronic illness in childhood, and likely has a multifactorial cause. It is known to begin very early in life and is more prevalent in westernized countries. Currently, there is growing interest in the microbiome theory to explain the development of atopic asthma. The authors explore one component of the possible relationship between a more westernized diet, low maternal fiber content, the change in the infant’s gut microbiome, and subsequent development of asthma.
“Their initial experiment used a mouse model, and a validated method of inducing asthma, to examine the hypothesis that a maternal high fiber diet would be protective in the development of airway disease in the offspring. They were able to demonstrate in mice that offspring of mothers given a high fiber diet had lower levels of biomarkers related to the development of airway disease and better lung function.
“They also demonstrated that the offspring of mice given a high fiber diet had significantly different gut flora with greater diversity, an increase in the number of B. acidifaciens, a species of gut bacteria, increased short-chain fatty acids in feces and serum, and increased acetate in serum than those in the control group.
“Due to the increase in B. acidifaciens (a high producer of acetate) and increased amount of serum acetate they evaluated whether acetate was associated with the reduction in development of asthma. They showed the effects of preventing asthma was directly related to increase amounts of acetate, as adding acetate to the water of pregnant mice had similar results on the airway as those given a high fiber diet.
“Finally, they correlated these findings in a small population of pregnant human women by measuring serum short chain fatty acids and recording dietary intake for the 24 hours prior to blood collection as well as parental report of their child’s wheezing history. They were able to demonstrate that: dietary fiber intake was associated with increased serum acetate levels, and also fewer infants born of mothers with serum acetate levels above the median had two or more general practitioner visits for cough/wheeze.
“The authors have made some very interesting and important observations which may lead to an improved understanding of one possible contributor to the high prevalence of asthma in westernized countries, and may lead to a safe and easy therapy. However, further research needs to be done to determine if the findings will be replicated in humans. For example, in the author’s supplementary findings, the reduction in frequency of visits for cough/wheeze was not seen if the mother had asthma. So it remains to be seen whether increasing dietary fiber in humans would lead to a reduction in asthma in children.
“Additional studies would also need to clarify additional questions including how much increase in dietary fiber is required, would consumption of other dietary products affect serum acetate/amount of dietary fiber consumption, a “target range” for serum acetate that is effective and safe, as well as other questions.
“This is study is certainly intriguing as increasing dietary fiber is already known to have many health benefits. Hopefully, this will lead to further prospective studies in humans.”
‘Evidence that asthma is a developmental origin disease influenced by maternal diet and bacterial metabolites‘ by Thorburn et al, published in Nature Communications on June 23,2015.
Declared interests (see GENeS register of interests policy):
No interests declared