Although the thought might leave some new parents feeling squeamish, the moment a child enters the world is also the moment that bacteria start entering the child. The colonization of the human gut by the wide range of bacteria collectively known as the gut microbiome begins shortly after birth, and disrupting its healthy development can lead to long-term health consequences including an increased risk of diabetes, obesity, asthma and infections.
The composition of a baby’s gut microbiome is impacted by mode of delivery and whether or not the babies are breastfed or fed formula milk. Interestingly, ethnicity is also known to influence the gut microbiome, although previous studies were not broadly generalizable as their subjects were limited to specific populations or were not followed over long periods of time.
To get around this problem, a team led by Neerja Karnani of A*STAR’s Singapore Institute for Clinical Sciences (SICS) used deep phenotyping to study 106 infants of three Asian ethnicities: Chinese, Malay and Indian. These children were part of the Growing Up in Singapore Towards Healthy Outcomes (GUSTO) birth cohort, a comprehensive nation-wide study of pregnancy and early life.
They found that the type of delivery, infant feeding practices and ethnicity all strongly affected the composition of the gut microbiome. For example, infants delivered by lower segment cesarean section (C-section) had a more diverse microbiota than those that were vaginally delivered. On the other hand, infants fed only or mainly with breastmilk had more potentially beneficial microbes.
Surprisingly, the gut microbiota of Indian, Chinese and Malay infants was different even at three months of age, when feeding of complementary foods has usually not yet started, said study first author Jia Xu, a Senior Research Fellow at SICS. Unlike the mode of delivery or breastfeeding, which influenced gut microbiome composition up to three and six months respectively, ethnic influences remained significant up to 12 months in Indian and Chinese babies, who had higher levels of Bifidobacterium and Bacteroides species respectively. These ethnic differences in infant gut microbiota composition could potentially stem from the impact of human genetics, microbiota of family members and the general household environment.
“The evidence for the existence of ethnic diversity in the infant gut microbiome even before the introduction of weaning diets strongly advocates for the consideration of ethnicity in future infant gut microbiome studies,” Karnani said.
The team is now studying the downstream effects of ethnically-differentiated diversity in infant gut microbiota and its potential impact on the health of the child. “Eventually, our objective would be to bring precision to early life probiotic interventions,” Karnani concluded.
The A*STAR-affiliated researchers contributing to this work are from the Singapore Institute for Clinical Sciences (SICS).