Taboos & Intestines

When we were growing up sex was taboo topic #1.  Our intestinal track, and what went in and came out was perhaps #2.  You or someone you know probably has IBS . . . it is rarely talked about or shared.  That’s beginning to change as research increasingly is showing the importance of our microbiome and has dubbed the “gut” as our second brain.

Signals generated by the brain can influence the composition of microbes residing in the intestine and that the chemicals in the gut can shape the human brain’s structure.

Researchers at UCLA have revealed two key findings for people about the relationship between the microorganisms that live in the gut and the brain:

1.   For people with IBS, research shows for the first time that there is an association between the gut microbiota and the brain regions involved in the processing of sensory information from their bodies.

2.  The researchers gained insight into the connections among childhood trauma, brain development and the composition of the gut microbiome.


“The UCLA researchers collected behavioral and clinical measures, stool samples and structural brain images from 29 adults diagnosed with IBS, and 23 healthy control subjects. They used DNA sequencing and various mathematical approaches to quantify composition, abundance and diversity of the gut microbiota. They also estimated the microbial gene content and gene products of the stool samples. Then the researchers cross-referenced these gut microbial measures with structural features of the brain.”

Based on the composition of the microbes in the gut, the samples from those diagnosed with IBS clustered into two subgroups:

  • One group was indistinguishable from the healthy control subjects, while the other differed.
  • Those in the group with an altered gut microbiota had more history of early life trauma and longer duration of IBS symptoms.
  • The two groups also displayed differences in brain structure.


“Analysis of a person’s gut microbiota may become a routine screening test for people with IBS in clinical practice, and in the future, therapies such as certain diets and probiotics may become personalized based on an individual’s gut microbial profile. At the same time, subgroups of people with IBS distinguished by brain and microbial signatures may show different responsiveness to brain-directed therapies such as mindfulness-based stress reduction, cognitive behavioral therapy and targeted drugs.

“A history of early life trauma has been shown to be associated with structural and functional brain changes and to alter gut microbial composition. It is possible that the signals the gut and its microbes get from the brain of an individual with a history of childhood trauma may lead to lifelong changes in the gut microbiome. These alterations in the gut microbiota may feed back into sensory brain regions, altering the sensitivity to gut stimuli, a hallmark of people with IBS.”

Clues about autism may come from the gut

Bacterial flora inhabiting the human gut have become one of the hottest topics in biological research. Up to a quadrillion (1014) bacteria inhabit the human intestine, contributing to digestion, producing vitamins and promoting GI health.

Genes associated with human intestinal flora are 100 times as plentiful as the body’s human genes, forming what some have referred to as a second genome. Various environmental factors can destabilize the natural microbiome of the gut, including antibiotics and specific diets. Hundreds of species inhabit the gut, and although most are beneficial, some can be very dangerous.  They are implicated in a range of important activities including:

  • Digestion
  • Fine-tuning body weight
  • Regulating immune response
  • Producing neurotransmitters that affect brain and behavior

“The prevalence of Autism in children exceeds juvenile diabetes, childhood cancer and pediatric AIDS combined. In terms of severe developmental ailments affecting children and young adults, autism is one of the most common, striking about 1 in 50 children. The disorder — often pitiless and perplexing — is characterized by an array of physical and behavioral symptoms including anxiety, depression, extreme rigidity, poor social functioning and an overall lack of independence.”

Researchers have been looking at the connection of gut bacteria and many diseases and conditions.  Autism is of interest because autistic children have a lot of gastrointestinal problems that can last into adulthood.  Studies have shown that when these GI problems are managed, autistic behavior dramatically improves.

“The current study confirmed these suspicions, and found that children with autism had significantly fewer types of gut bacteria, probably making them more vulnerable to pathogenic bacteria. Autistic subjects also had significantly lower amounts of three critical bacteria, Prevotella, Coprococcus, and Veillonellaceae.

Controversy surrounds the apparent explosive rise in autism cases. Heightened awareness of autism spectrum disorders and more diligent efforts at diagnosis must account for some of the increase, yet many researchers believe a genuine epidemic is occurring. In addition to hereditary components, Western-style diets and overuse of antibiotics at an early age may be contributing to the problem by lowering the diversity of the gut microflora.

Lower diversity of gut microbes was positively correlated with the presence of autistic symptoms in the study. The authors stress that bacterial richness and diversity are essential for maintaining a robust and adaptable bacterial community capable of fighting off environmental challenges. “We believe that a diverse gut is a healthy gut,” Krajmalnik-Brown says.


Clues About Autism May Come from the Gut

Rosa Krajmalnik-Brown, Dae-Wook Kang and Jin Gyoon Park are researchers at Arizona State University’s Biodesign Institute.