Before birth, one would think an infant has little need for a good gut microbiome, as they are fed directly by the cord to the bloodstream. However, we know that the maternal diet is essential in creating a microbiome in the infant at birth. Some bacteria are shared through the placenta, but birth is where the biome starts. To start an infant off well, many things have to happen, and we cannot always control all the factors. Diet is one that we can control. Studies on how the diet affects the bacteria transferred to babies started with a study on rats, how their diets affected their gut biome, and how that transferred to their pups. This study concluded that a high-fat diet changed the gut biome so that the bacteria shared during pregnancy, birth, and lactation was not highly varied and was mostly pathogenic rather than helpful. (Mann et al., 2017)
In human studies, we found similar results. In a study published in Genome Medicine (Chu et al., 2016), mothers were separated into high-fat and standard or low-fat diets groups. The infants’ stool and meconium were tested, and a few areas on the body for bacteria and the bacteria were then sequenced. Enterococcus had a marked increase in the high-fat diet group and a marked decrease in Bacteroides, which aid in supporting mucosal immunity. These changes persisted up to six weeks postpartum, even with some of the infants being breastfed. So we know that maternal diet will affect the infants’ gut biome even several weeks after birth.
Along with diet, we know that mode of delivery, medications, and breastmilk can also affect the development of the gut biome. Starting with birth, the gut biome can change based on delivery. If mom has antibiotics or delivers by cesarean section, the transfer of bacteria from the vaginal canal is either incomplete or altered. However, the composition in the milk doesn’t change much by these factors and has more to do with a mother’s diet and BMI. (Demmelmair et al., 2020) Some small studies showed an increase in harmful bacteria over helpful in the milk in cesarean section milk, but other studies show little to no difference. The inconsistencies may have to do with the area or hospital practices instead. Also included in the study were the differences in breastmilk and formula. There was a higher increase of diversity in healthy bacteria in infants fed breastmilk, particularly at the breast, than those fed by bottle, tube, or formula. While all of this may seem upsetting or daunting as having to have antibiotics or a cesarean section are out of our control, there is hope.
Mothers can prepare a healthy gut biome for their infant by eating a regular fat diet and limiting healthy fats that feed beneficial bacteria like bifidobacterium and lactobacillus before birth. They can then continue this diet after birth for their milk. Breastfeeding over formula feeding has long been proven to be the best food for infants, and it’s true also for the gut biome. Even if other factors alter the gut biome, breastmilk can help heal and change it over time. It’s been found that bacterial diversity is also determined by maternal weight and diet but still improved over formula, which feeds primarily harmful bacteria, just with lower variety. (Cabrera-Rubio et al., 2012) Colostrum tested showed only a few bacteria, mainly from the lactobacillus family, but by six months, including those bacteria Veillonella, Leptotrichia, and Prevotella were also found. Maternal diet did affect the diversity by limiting these healthy bacteria while having increased levels of coccus-type bacteria.
While these studies show that diet is vital in developing a healthy gut microbiome for infants, and the importance cannot be understated, we can also affect the biome after birth by breastfeeding. Breastfeeding provides a higher diversity of healthy and helpful symbiotic bacteria that strengthens the gut and our immunity. We don’t always choose how we give birth or need medication, but we can control our diets, and we can seek help in breastfeeding so that we offer our infants the best start in life.
References
Cabrera-Rubio, R., Collado, M. C., Laitinen, K., Salminen, S., Isolauri, E., & Mira, A. (2012, July 25). The human milk microbiome changes over lactation and is shaped by maternal weight and mode of delivery. The American Journal of Clinical Nutrition, 96(3), 544-551. https://doi.org/10.3945/ajcn.112.037382
Chu, D. M., Antony, K. M., Ma, J., Prince, A. L., Showalter, L., Moller, M., & Aagaard, K. M. (2016, August 9). The early infant gut microbiome varies in association with a maternal high-fat diet. Genome Medicine, 8(77). https://genomemedicine.biomedcentral.com/articles/10.1186/s13073-016-0330-z
Demmelmair, H., Jimenez, E., Carmen Callado, M., Salminen, S., & McGuire, M. K. (2020, March 9). Maternal and Perinatal Factors Associated with the Human Milk Microbiome. Current Developments in Nutrition, 4(4). https://doi.org/10.1093/cdn/nzaa027
Mann, P. E., Huynh, K., & Widmer, G. (2017, November 28). Maternal high fat diet and its consequence on the gut microbiome: A rat model. Gut Microbes, 9(2), 143-154. https://doi.org/10.1080/19490976.2017.1395122
