Let’s talk about bowels. They’re not the most glamorous of topics, and when they come up in conversation most of us wrinkle our noses in disgust. But it can’t be denied that they do much of our dirty work for us – and in fact research is beginning to show that our guts may have a much larger impact on our lives than previously believed.
A number of studies have demonstrated a strong link between the chemical and bacterial composition of the gut, and changes in brain function, including the development of Autism Spectrum Disorder. Autism is a complex disorder, primarily characterised by a strong lack social and communication ability, along with restrictive behaviour. Diagnosis can mean a difficult life for a parent or carer, who will often look after their child well into adulthood. Although it is widely studied by scientists, there are as yet no methods of prevention, nor are there any widely accepted causes.
Slowly gaining credibility, however, is the theory that autism is partially caused by abnormal intestinal chemicals. One recent study undertaken in The Netherlands had provided further evidence of such causality, and looked specifically at the role that allergic reactions to food can play in changes to the brain. Within the experiment, scientists looked at the brain chemicals, gut chemicals and behaviour of mice, before and after they had experienced an allergic reaction. After the reaction, the mice brains were observed to have much higher levels of serotonin, an important biological symptom of autism. This was probably caused by the higher levels of of 5-HT (a protein involved in serotonin synthesis) which were observed in the intestines. Most strikingly, the behaviour of the mice post-reaction changed to a significant degree. The mice began to avoid social interaction, and displayed lower cognitive function as well as more repetitive behaviour. These are three of the key behavioural symptoms of autism.
At a first glance, the idea that something as simple as a food allergy can trigger the onset of autism seems unlikely. After all, about one in twenty Australian have an allergy, but less than one in a hundred has autism. However, the researchers are not suggesting that allergies are the main causal factor for Autism Spectrum Disorder. Rather, it may be one of many factors, including genetic predisposition, that when combined can trigger the onset of the disorder.
The study provides compelling evidence for the linkage of the gut and the brain. It certainly seems as though taking care of your intestinal health, whether it be through maintaining a fibrous diet or taking a daily probiotic, is likely to have benefits for your mental health too. It may be some time until experts prove this conclusively – but until then I’ll keep eating my yoghurt!