High-Fibre Diet During Pregnancy May Guard Offspring Against Asthma

WOMEN who consume a high-fibre diet during pregnancy may reduce the risk of their offspring developing asthma, according to new study data.

Led by Dr Alison Thorburn, Department of Immunology, Monash University, Melbourne, Australia, the study indicated that a high-fibre diet alters a mother’s gut bacteria during pregnancy, producing anti-inflammatory substances that suppress asthma-related genes in offspring. The team fed pregnant mice one of three diets during their third trimester: a high-fibre diet, a moderate-fibre diet, or a low-fibre diet. When the offspring became adults, they were exposed to house dust mites – a trigger for asthma in humans.

The researchers discovered that the offspring whose mothers were fed a high-fibre diet during pregnancy did not develop asthma-like symptoms, whereas the offspring whose mothers were fed a low-fibre diet did. Further examination showed that the pregnant mice fed a high-fibre diet experienced changes in gut bacteria; they possessed specific microbes that produced anti-inflammatory metabolites when the fibre was digested. These metabolites circulated around the bloodstream and travelled through the uterus to the fetus, suppressing Foxp3 genes linked to asthma development.

The team then tested whether this theory also applied to humans; they analysed the blood samples and diet data of 40 women, as well as data describing the frequency of doctor’s visits due to respiratory symptoms in their offspring during the first year of life. The results revealed that women who consumed a high-fibre diet throughout their pregnancy also had anti-inflammatory metabolites in their blood, and the offspring of these women were significantly less likely to have visited the doctor two or more times due to respiratory complaints in their first year of life.

The researchers commented on the findings: “High fibre […] suppresses expression of certain genes in the mouse fetal lung linked to both human asthma and mouse allergic airway disease. Thus, diet acting on the gut microbiota profoundly influences airway responses, and may represent an approach to prevent asthma, including during pregnancy.”

Additionally, the team said that the results could explain why children who grow up on farms appear to be at lower asthma risk. “We speculate [this] may relate to dietary differences between rural and urban settings,” they explained, “or may relate to microbes encountered in the farm environment that are geared for high short-chain fatty acid production (that is, faeces from livestock that mostly digest fibre).”

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