Yeast (Candia albicans being the most common) is a pathogen, but it lives in check with the good bacteria in our intestinal tract. When we take antibiotics (anti = against life) to kill the pathogenic bacteria, we are not only killing the bad bacteria but also the beneficial bacteria (competition against yeast) in our intestinal tracts. This allows the yeast to overgrow. It then becomes difficult for the beneficial bacteria to re-populate.
This can happen with anyone, healthy or not, from one or many courses of antibiotics. But because of their existing imbalances (digestion, immune function, etc.), it appears to affect autistic children more severely. Antibiotics are not the only cause of yeast overgrowth, but they are often a major contributing factor. Dysbiosis (imbalance of gut organisms) can be caused by a variety of factors: excessive use of antibiotics, decreased digestive secretions (seen with faulty sulfation) dietary factors (sugars feed yeast and effect yeast growth significantly), impaired immunity, impaired liver function (seen with faulty sulfation), corticosteroids, fluoridated and chlorinated water, nutrient deficiencies, lack of beneficial flora, etc.
Elevated levels of candida (yeast) and yeast byproducts are common in children with autism, as is poor digestion. This may be due to the fact that children with autism often get ear infections, and thus receive (more than average) antibiotics. Toxic metabolites from dysbiosis, such as alcohol and formaldehyde, negatively affect the gut and brain. This is evidenced by the correlation between the amount of yeast/toxins and the severity of autistic symptoms as yeast and yeast toxins decrease, so (typically) do many autistic symptoms.
Common symptoms of yeast overgrowth include: gas, bloating, constipation or diarrhea, hyperactivity, spacey, inattentive, and fuzzy thinking, yeast infections (vaginal, nail fungus, athlete’s foot, or thrush), irritability, and inappropriate laughter. Yeast negatively affects many functions and can damage the immune system. It can also disrupt the digestive enzymes and create inflammation in the gut. Without the proper digestive enzymes and intestinal wall integrity, nutrients will not be optimally absorbed. They can cause leaky gut and contribute to food sensitivities and opiate exposure in the brain from wheat and dairy. The yeast can produce analogs of the Krebs cycles that inhibit energy production.
Addressing yeast through diet and supplements that kill candida, healing the gut, and balancing the microorganisms can provide significant relief and improvement to many of the symptoms of those with autism and anyone suffering with yeast overgrowth. See Body Ecology Diet and Specific Carbohydrate Diet for details on these diets.