ARI Publication 40 – 2013 Version
Gut Treatments: Anti-fungals and Probiotics
Rationale: The human gut contains a large number of bacteria (lOx more gut bacteria than cells
in the entire body). Most of these gut bacteria are beneficial, helping with food digestion and water
balance, producing some vitamins, and limiting the growth of harmful bacteria and yeast.
One of the most striking differences in the medical history of children with autism is that several
studies have reported much higher use of oral antibiotics (usually for ear infections) in infancy of
children with autism compared to controls. These oral antibiotics will destroy most of the beneficial
gut bacteria, and thus increase the risk of overgrowth of harmful bacteria and/or yeast.
Harmful bacteria and yeast produce toxins that can severely affect mental functioning and behavior;
alcohol is just one of many toxins that yeast can produce, and is a good example of a yeast toxin
that can severely affect behavior. It seems that the best way to treat these problems is with a
combination of antifungal diet, antifungal medications (if yeast are present) and probiotics
(beneficial bacteria). These can help restore normal gut function. Antibiotics should only be
considered as a last resort in most cases, as ARI survey data suggest they are more likely to cause
harm than help.
Anti-fungal Diet: Yeast feed on sugar and simple carbohydrates, so reducing or avoiding those
foods is important. Also, it can be helpful to avoid foods containing yeast or yeast products,
including fruit juice, vinegar (in ketchup and other foods), leavened foods (bread, pizza, bagels,
rolls), cheese, and mushrooms (a type of yeast/fungus).
Duration: Dr. Sidney Baker recommends a trial for 5-14 days, followed by a high exposure to see
if the diet makes a difference. If so, continue long-term.
Anti-fungal Medications: There are several prescription and non-prescription anti-fungal
treatments, and sometimes several need to be tried before finding an effective one for a given
strain of yeast. Nystatin is the safest because it is not absorbed, but many yeast are now resistant
to it. Diflucan, Sporanox, Lamisil, and Nizoral are alternatives to which yeast are less likely to be
resistant, but since they are absorbed into the body they have a very small chance of overtaxing the
liver, and liver enzymes should be checked every few months if they are used long-term. (Note that
there is no published research supporting this approach, merely the clinical experience of some
MDs.) Some non-prescription antifungal treatments include capryllic acid, oregano concentrate,
citrus seed extract, undecylenic acid, and pau d’arco.
Duration: Dr. Sidney Baker recommends a series of high-dose trials of 2-3 weeks for each
antifungal, followed by the next one until you find one that works.
Die-off reaction: When yeast are killed, they can release all their toxins at once. This can cause
a temporary “die-off” reaction lasting a few days, followed by good improvement when the toxins
leave the body. Activated charcoal can be taken to absorb these toxins and reduce side-effects.
Probiotics: Probiotics are mixtures of one or more beneficial bacteria that are normally present in
the gut. Many probiotics contain only a few billion Colony Forming Units (CFU’s), but some strong
probiotics contain 30-75 billion CFU’s, and some prescription probiotics contain up to 500 billion
CFU’s. The higher-dose products are more likely to be able to reach the gut and recolonize it with
good bacteria. If high-dose probiotics continue to be needed, this may suggest pancreatitis or other
serious dysfunction is present.