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September 11, 2023

Maternal Nutrition and the Microbiome

Part I

This was a tricky topic to drill down into one article - so I split it into two. Bear with me on this topic as it is so important in the grander scheme of maternal and child health. 

The microbiome by definition: the microorganisms that reside in a particular environment.

Pregnancy is a dynamic event where a woman's body changes radically, including epigenetically, hormonally, immunologically and physiologically in order to conceive and carry a baby to term. Pregnancy has always been a scientific fascination because of these changes. Now, we add the microbiome to the list, as it is the latest area of research that is shedding light on how pregnancy outcomes are determined.  

The maternal microbiome is defined as the community of organisms that inhabit a woman's mucosal and skin surfaces. These organisms are bacteria, fungi, archae and viruses. These opportunistic players affect us in ways previously thought impossible. "We hypothesize that an appropriate microbiota is essential for healthy early development, pregnancy maintenance, and the first years of childhood." (Nuriel Ohayon et. al. 2016) 

What dictates the health of a gut microbiome and its importance in pregnancy? Is it necessary to have the microbiome set before conception? What is damaging the microbiome? 

The gut microbiome, for the purposes of this article, will be simplified down to being primarily made up of trillions of bacteria that have the ability to help us or hurt us based on their type, volume, and balance. We live with them as much as they live with us. We supply each other with food sources and nutrients. The end result is a symbiotic ecosystem within us. 

How is the maternal microbiome established? Here are two competing modern types. 

1) This pattern is associated with better health.

The microbiome for mom was established at her birth with her passage through the vaginal canal and her subsequent exposure to the vaginal and rectal bacterial flora of her mother. Then mom further upgrades her microbiome by latching onto the breast to feed herself as an infant. Breastmilk is the perfect food source for her bacteria as it is made up of greater than 10% non digestible sugars, called human milk oligosaccharides, HMO. Babies lack enzymes to break down these sugars leaving them for the bacteria to have a party with. Over the next few years, mom's gut microbes will be shifted and established by the food that she eats, medicines and chemicals that she is exposed to, stress events and much more. 


2) This pattern is associated with worse health.

The microbiome for mom was established at birth with her passage through a c section opening in her mother's abdomen and her subsequent exposure to the skin and gloves of the doctor and staff. Then mom further alters her microbiome by latching onto a bottle of cow's milk formula to feed. Formula milk is not the perfect food source for her bacteria as it is not made up of these excellent non digestible sugars and is not dynamic over time. Over the next few years, mom's gut microbes will be shifted and established by the food that she eats, medicines and chemicals that she is exposed to, stress events and much more. (Pollan 2013)

Now that mom's microbiome has been established, she becomes the primary influence for her baby's microbiome. This process repeats itself through the generations from mother to child. (Dunlop et. al. 2015) If mom's microbiome is the main player in starting her baby on the right track, what else influences her microbiome?

A little aside on the HMO's because of their importance: breastmilk provides for over 220 milk oligosaccharides (HMO) or small sugars that are indigestible by the human infant but are digestible by the infants intestinal microbes. This is an incredible evolutionary task for a mother to use her energy to make a food source for bacteria that is roughly 15% of breastmilk composition. The reason is clear. There is a profound symbiosis between a human and the intestinal microbiome. As discussed in the podcast with Dr. Shafizadeh, the specific intestinal microbes that are present in the intestines will dictate which HMOs' are metabolized and thus conferring health benefits to the child. Breastmilk is loaded with diverse HMO's and are giving a child the best health outcomes. Formula has recently added 2 HMO's out of the 220+ in order to meet this scientific health understanding. Thus, with the lack of diversity, it is only a matter of time until we learn about all of the missing benefits of the other HMO's in breastmilk.

The most critical long term aspect shaping the gut microbiome over time after it is established at birth is the primary influence of diet.

Study after study has shown us that the nutritional influences of diet dictate the biodiversity and health of the intestinal bacteria. (Sonnenburg et. al. 2016) "Diets high in certain fats and sugars deplete anti-inflammatory bacteria, thin the mucous layer and foster systemic inflammation." (Velasquez-Manoff 2015) The critical player in the "I want to feed my good gut bugs game" is FIBER which is predominantly found in fruits, legumes and vegetables. 

When researchers looked at human gut microbiomes and compared them across cultures, they found that increased microbial diversity, which correlates with better health, was predicted by a diet loaded with fiber and that the introduction of high volumes of animal meats, fat and refined carbohydrates caused a dramatic shift in the bacteria toward a less diverse and dysfunctional type. (DeFillipo et. al. 2017)(Schnorr et. al. 2014)

Pause: Summary so far: 

Mom has a gut microbiome that directly seeds her baby's microbiome. This microbiome dictates human long term and short term health. Eating a diet loaded with fiber based fruits, legumes and vegetables will cause a highly diverse bacterial microbiome to exist and this existence is correlated with health. 

Part two next week,

Dr. M

Advances in Neonatal Care Dunlop Article

Nature Sonnenburg Article

Nature Velasquez-Manoff Article

Frontiers in Microbiology DeFillipo Article

Nature Schnorr Article

Gut Microbes Mann Article

Genome Medicine Chu Article

Cell Koren Article

Medical Hypothesis Zhang Article

Frontiers in Microbiology Nuriel Ohayon Article

The Scientist Gren Article

New York Times Pollan Article