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