Could the bacteria found in a baby's gut be a link between cesarean sections, infant formula, and Autism?
Current research is demonstrating that the bacteria found in your gut affects your behavior - additionally, research is also demonstrating that infants fed infant formula and delivered by cesarean surgery have altered gut microbiota, is it possible this is a link between cesarean delivery, infant formula and behavioral disorders such as Autism? Such a link could have substantial repercussions on our population's health.
Research from UCLA(1) demonstrates that the brain-gut communication flows in both directions.When women were fed yogurt with probiotics, their brainstem and prefrontal cortex were more active (measured using fMRI), meaning that the rational decision making center of their brain was receiving, interpreting, and responding to messages from the body. Conversely, a group of women who received no probiotics or yogurt had greater connectivity between the brainstem and emotional-sensation regions of the brain - think tantrums, road-rage... times when we are irrational and make decisions with our emotions.
Simply, what these women ate in their diets effected the manner in which their brain operated.
Furthermore, researchers in Ireland just published a study in Molecular Psychiatry(2) which found that mice with altered, inadequate, or missing bacteria in their intestinal flora demonstrated social impairments and behaviors similar to those seen in Autism. When treated with a better diet, one that brought microbiota back to normal levels, the mice improved in some, but not all behaviors.
So, missing crucial bacteria in their gut appears to have altered the developing mouse brain... and led to behaviors similar to those seen in Autism models.
This alone is alarming considering the inadequate diets many of us consume, what that diet may be doing to our brains, and what this means for the brains of our rapidly developing children.
But this isn't necessarily what I am most concerned about. You see, research has also demonstrated that babies born by cesarean section (and babies fed infant formula) have altered and missing bacteria in their gut... could our cesarean epidemic and over-use of infant formula be contributing to our high rates of Autism?
So here is my question...
If gut microbiota influence the way the brain operates, and subsequently how behavior is expressed, AND common obstetrical and infant procedures such as cesarean delivery and infant formula feeding alter the gut microbiota in a rapidly developing infant, then could these routinely used interventions be contributing to some cases of Autism?
Cesarean Sections, gut microbiota and Autism.
Autism diagnosis has been increasing at a rather alarming rate. Some of this increase can be attributed to our improved ability to diagnose Autism, but just some. This increase in the rate of Autism is likely due to many factors, both environmental and genetic.
Researchers have been looking at the prenatal, perinatal, and postnatal periods of development to determine if any procedures, exposures, or experiences, were correlated with an increased risk for Autism. Of course, because Autism is so prevalent, many things are correlated with an increase (such as maternal and paternal age), but when researchers control for a variety of important factors, a few obstetrical events/procedures appear to be risk factors for Autism... one of those is planned Cesarean section (Pediatrics, 2009)(3).
Azad et al. (2013)(4) found that when compared to babies born vaginally, babies born by cesarean section had lower levels of certain bacteria, and were completely lacking bacteria from the phylum Bacteriodetes. Babies born by elective cesarean showed the greatest changes and decreases in gut bacteria. Could this absent bacteria be a factor in their Autistic behavior, such as that seen in the mouse model?
The authors make note that it isn't clear whether bacterial diversity and richness is clinically significant OR if specific "beneficial" organisms being present is more important. But either way, there are CLEAR differences in the gut microbiota of babies born vaginally compared to those born by cesarean, and something we should be concerned about considering about 1/3 of the babies in the U.S. are delivered by Cesarean.
Babies born by Cesarean section are not exposed to the wealth of maternal microbes that nature intended, what are the repercussions of this? Could this explain why Pediatrics (2009)(3) found an increased risk for Autism in babies delivered by planned (often elective) Cesarean deliveries?
What about Infant Formula?
A study from Tannock et al. (2013)(5) demonstrated differences between levels and types of bacterial flora in an infant's gut when fed breastmilk,goat-milk derived infant formula, and cow-milk derived infant formula. Their key findings were two-fold. First, the types of bacteria and amount of bacteria present in the infant's gut were VERY different between breast-fed babies and those fed formula. Secondly, goat-milk derived infant formula leads to bacteria levels and types that are more similar to breast-fed babies that those that are fed cow-milk derived formula. For example, Bacteroidaceae was more abundant in breast-fed babies, hardly found in infants fed goat-milk derived formulas, and absent in infants fed cow-milk derived formula. Unfortunately, cow-milk derived formula is what is most commonly fed to infants.
Azad et al. (2013)(4) found that babies fed infant formula had an overabundance of two bacteria, Peptostreptococcaceae and Verrucomicrobiaceae, what is important about this is that C. difficile, (a member of the Peptostreptococcaceae family) is a pathogen associated with enteric and atopic disease - of which babies fed infant formula suffer from more frequently! Exclusively breastfed babies actually had less bacterial diversity than babies fed infant formula... possibly due to a selective and protective effect of breastmilk, keeping out (destroying or weakening) dangerous bacteria such as C. difficile and keeping babies fed breastmilk healthier!
I am not saying that cesarean deliveries and feeding your baby infant formula will give them Autism, just that there is growing evidence of a relationship between gut bacteria, brain function, and behavior... and that cesarean sections and infant formula have been shown to alter the gut bacteria in an infant. On a population scale, the repercussions could be substantial.
I am not an expert on diet, the brain, or Autism. I am only trying to understand the research and evaluate an incredibly complex issue. However, I do think our routine OVER-USE of obstetrical procedures and medicine (Yes, infant formula is medicine!) are not without their consequences. We should not ignore the potential negative effect that our extremely high cesarean rate and our very high use of infant formula may be having on our children's health. I truly hope there is not a connection between Cesarean delivery and Autism, but why risk it if we aren't sure!?
PLEASE feel free to leave comments, I would LOVE to hear what you have to say!
And while you are at it, why not start eating healthier, it helps your brain function better!
~Wisdom and Birth
(1) Champeau, R. Changing gut bacteria through diet affects brain function, UCLA study shows. UCLA Newsroom, May 28, 2013.
(2) Desbonnet L, Clarke G, Shanahan F, Dinan TG, Cryan JF. Microbiota is essential for social development in the mouse. Molecular Psychiarty; 21 May 2013. doi: 10.1038/mp.2013.65
(3) Guinchat V, Thorsen P, Laurent C, Cans C, Bodeau N, Cohen D. Pre-, Peri- and neonatal risk factors for autism. Acta Obstet Gynecol Scand, 2012 March; 91(3):287-300. doi: 10.1111/j.1600-0412.2011.01325.x.
(4) Azad MB, Konya T, Maughan H, Guttman DS, Field CJ, et al. Gut microbiota of healthy Canadian infants: profiles by mode of delivery and infant diet at 4 months. Canadian Medical Association Journal, 2013 March; 185(5). DOI:10.1503/cmaj.121189
(5) Tannock GW, Lawley B, Munro K, Pathmanathan SG, Zhou SJ, et al. Comparison of the compositions of the stool microbiotas of infants fed goat milk formula, cow-milk based formula, or breast milk. Applied and Environmental Microbiology, 2013 May; 79(9):3040-3048.