We know probiotics affect neurotransmitter balance. How, what is the mechanism, and are there one or a few strains that are particularly useful in autism?

Microbiota, in general, influence neurotransmission both in the enteric nervous system that surrounds the GI tract and remotely in the brain. Microbes themselves are known to produce a variety of metabolites and neuroactive molecules that can act locally on the intestinal physiology and function as well as through neural pathways, immune signaling, or other mechanisms to influence brain function. Probiotics can have beneficial effects on health and brain function through influencing immune system function, aiding digestion, and by producing beneficial metabolites.

To date there is no clear evidence that indicates specific strains of bacteria or specific probiotics for autism. Respected experts in probiotics agree that the benefits reported in one study are specifically related to the tested probiotic and its formulation. Find out more about indications and probiotics available in the US at http://usprobioticguide.com or in Canada at http://www.probioticchart.ca/PBCIntroduction.html. 

This question was answered by Jane Foster, PhD.