Autism & Digestive Health

People with autism often have more digestive health problems than average. 1 in 4 children with autism (see Probiotics Learning Lab for glossary) are thought to have at least one chronic gastrointestinal symptom1 and numerous studies have discovered abnormal digestive health conditions in people with autism2,3. Autistic children have also been found to have more Clostridia (a type of pathogenic bacteria) in the gut than children without autism4 and a recently published study5 found a little known bacterial genus called Sutterella present in microbiota in just over half the participants with autism, but in none of those without autism.

Some research suggests that microorganisms support digestive health in adults and children. So could live cultures help children or adults with autism?

boy with autism
Autism is thought to be five times more common in boys than girls

Probiotics for Autism: A look at the Research

Clinical Research

Probably the best known UK clinical study into probiotics for autism was the unfinished trial run in 2006 by Professor Glenn Gibson at the University of Reading; referred to by some as the trial which was "so successful, that it failed". 40 autistic children all between 4 and 13 years old were randomly separated into a trial group, and a control group. The trial group were given a probiotic supplement with the species Lactobacillus plantarum whilst children in the other group were given placebos (read about placebo-controlled studies here). The trial was supposed to continue this way for three weeks, before the groups would switch supplements and continue as such for a further three weeks. However researchers reported that the Lactobacillus probiotics had such a positive effect on the participants, that the 'blind' aspect of the trial fell through. Parents of participants in the probiotic group could see a noticeable effect, and said it was heartbreaking to have to stop their child from taking the probiotics. Too many participants dropped out of the trial when they were supposed to switch over.

Clinical trials are important to gauge the efficacy of any supplement or medicine. Find out about our clinical trials here.

Comments from parents6 of participants in the probiotic group included not only reports on digestive health improvements, such as, 'better formed stools' but also potentially behavioural improvements, such as, 'more calm, relaxed' and 'improved ability to listen and concentrate'. It is certainly worth mentioning that these comments are taken from a few parents, and also that interestingly, during the trial the parents' overview of the effects of the probiotics tended to be more positive than the view of the teachers. Finally, the study saw a large drop out rate which meant it could not continue.

We have not been able to ascertain which strain of the L. plantarum species was used; reports of the trial state only that this strain was non-commercial. Research demonstrates that any beneficial effects of probiotics are strain-specific (ie. the benefits must ideally be associated with a specific probiotic strain, and not simply a species).

Clinical Review:

A 2017 review of clinical research 7, by Dr. Qinrui Li from Peking University Hospital, Beijing analysed more than 150 scientific papers, dating back as far as the 1960's, in order to ascertain the impact of taking either prebiotics or probiotics on the symptoms of Autistic Spectrum Disorders (ASD). The review which was published in the Journal ‘Frontiers in Cellular Neuroscience’ also assessed the impact of changes in diet, such as following a casein or gluten free diet, on the condition.

Results of the review show that improving the health of the intestinal flora eases autism symptoms and improves sufferers’ social behaviours and ability to interact. Improvements were seen with both pre- and probiotic intervention and also with elimination diets. Researchers found that the improvements to symptoms that were achieved with dietary changes were mainly as a result of reduced intestinal inflammation and therefore reduced intestinal permeability, and leaking of toxins in to the bloodstream. Improvements seen as a result of pre- and probiotic supplementation however, were thought to occur as a result of strengthened activity in areas of the brain that are responsible for emotion. Pre- and probiotics effect our emotional responses via their interaction with the gut-brain axis, however they are also known to improve the health of the intestinal lining and to help to reverse intestinal permeability. This too will have positive repercussions for the symptoms of ASD via a reduction in circulating toxins that can affect the nervous system.

Following the review Dr Li said:

'Efforts to restore the gut microbiota to that of a healthy person has been shown to be really effective. Our review looked at taking probiotics, prebiotics, changing the diet - for example, to gluten- and casein-free diets. All had a positive impact on symptoms.'

When asked how the results of the review might benefit patients in the future, she added:

'We would hope that our review leads to research on the link between the gut microbiota and ASD, and eventually a cheap and effective treatment.'

Research in animal models

Whilst there are still relatively few human clinical trials investigating the link between gut flora and autism, scientists at Baylor College of medicine in Texas have recently been looking at the impacts of gut flora on the behavioural development of mice. Senior study author, Dr. Mauro Costa-Mattioli, said that the inspiration for the study8 was taken from earlier human studies that have shown a correlation between maternal obesity during pregnancy and the risk of their offspring developing various neurodevelopmental disorders, including autistic spectrum disorders.

In the study, it was found that young mice born to overweight mothers showed behavioural deficits, including spending less time in contact with other young mice, and not initiating social interactions. Both of these character traits are common in autistic spectrum disorders in humans. Moreover the bacterial composition of the young mice born to overweight mothers was also different from those born to healthy-weight mothers. In particular one type of bacteria, Lactobacillus reuteri, was reduced more than nine fold in the microbiome of the mice born to the over-weight group.

Based on these findings, the research team cultured a strain of L. reuteri, and put it in the drinking water of the unhealthy high-fat-diet offspring. They found that the inclusion of this one single strain of probiotic bacteria was enough to rectify their anti-social behaviour traits. Interestingly, the research also showed that this single strain of bacteria promoted the production of a ‘bonding hormone’, which is understood to play a crucial part in social behaviour in humans. A lack of this bonding hormone in humans has been associated with autism and autistic spectrum disorders.

A separate recent animal study has tried to further our understanding of the role the gut microbiome plays in influencing brain and nervous system function9. It was found that certain groups of bacteria seemed to have an effect on cortisol and serotonin levels. The research is still at the exploratory stage, and a lot more awaits discovery before we can have a firmer understanding of the interplay between gut and brain. Although still in the dark, research is consistently showing a connection between the gut microbiome and nervous system.

More research needed

A great deal more clinical research is necessary before any firm conclusions can be made as to the effect of probiotics on autistic children and adults; preferably with large, randomised and double-blind clinical trials. Professor Gibson has expressed a desire to undertake a larger study in the future with fewer drop outs.

Autism & Diet

Some people believe that the symptoms of autism can be controlled in part by dietary changes, hence a fair amount of those on the autistic spectrum cut out certain foods which are thought to be difficult to digest. In particular many children and adults with autism take on a gluten & casein free diet (known by many as the GF/CF diet). There is not a huge amount of clinical research on the GF/CF diet, and drawbacks could potentially include decrease in certain useful white blood cells10 as well as difficulty in reintroducing foods containing elements of gluten or casein. However, some anecdotal evidence suggests that the GF/CF diet could not only help improve digestive health, but also to improve attention & concentration, communication and language, and social integration, amongst other behavioural changes. Other foods which people cut out or reduce include MSG and aspartame flavour-enhancing ingredients, lutein, feingold and complex carbohydrates, starches and processed sugars.

Once again, large and reliable clinical trials into the effects of diet on those on the autistic spectrum would be warmly welcomed and must be called for. It is always best for individuals to see a dietitian or nutritionist before eliminating certain foods in one's diet. In the meantime, anecdotal evidence that diet can alter the symptoms of autism provides further promise for the link between autism and gut health.


1.Molloy CA. et al (2003). Prevalence of chronic gastrointestinal symptoms in children with autism and autistic spectrum disorders. Autism. 7:165-171.

2. Finegold. SM. et al (2002) Gastrointesintal microflora studies in late-onset autism. Clinical Infectious Diseases 35: S6-516.

3. Parracho H. et al (2005) Differences between the gut microflora of children with autistic spectrum disorders and that of healthy children. Journal of Medical Microbiology 54: 987 - 991.

4. Song, Yuli. et al (2004) Real-Time PCR Quantitation of Clostridia in Feces of Autistic Children. Appl Enciron Microbiol 70(11): 6459-6465.

5. Williams, BL, Hornig M, Parekh T, Lipkin WI. (2012) Application of novel PCR-based methods for detection, quantitation, and phylogenetic characterization of Sutterella species in intestinal biopsy samples from children with autism and gastrointestinal disturbances. mBio 3(1):e00261-11. doi:10.1128/mBio.00261-11


7. The Gut Microbiota and Autism Spectrum Disorders. Qinrui Li, Ying Han*, Angel Belle C. Dy and Randi J. Hagerman. Front. Cell. Neurosci., 28 April 2017.

8. Single species of gut bacteria can reverse autism-related social behaviour in mice. Baylor College of MedicineBaylor College of Medicine NewsNeuroscienceSingle species of gut bacteria can reverse autism-related social behavior in mice.

9. Mudd (2017) Serum cortisol mediates the relationship between fecal Ruminococcus and brain N-acetylaspartate in the young pig. Gut Microbes. 13:1-12. doi: 10.1080/19490976.2017.1353849.

10. Ashwood P. et al (2003). Intestinal lymphoctye populations in children with regressive autism: evidence for extensive mucosal immunopathology. Journal of Clinical Immunology 23: 504-517.

Please note that the views & comments expressed on the blogs mentioned above are not our own, nor are they endorsed by OptiBac Probiotics.



  • I have a son age 2 yrs and 6months. He was diagnosed with severe Autism at 27 months old. He has digestive problems (switching between very soft yellow stools and very hard round stools) he also suffered with silent reflux as a newborn until 10 months which has now returned as regular reflux. He is non-verbal with a Global Developmental Delay. He is has a dairy intollerence and requires melatonin to sleep. I found this website after looking at many interviews with doctors who have done studies on children with autism and the benefits of probiotics. I carefully read the reviews before ordering and have decided that if the best that happens is that it helps his reflux and digestive problems then we shall be very happy. But...if the seemingly impossible happens (as documented in many studies) that it can de-fog the brain increasing the childs ability to start to speak, then this may just change our lives! So...I am currently awaiting the delivery of one months supply of the child probiotics at 2 sachets per day and shall be keeping a diary. I will post any notable changes x

  • After the daily mail news article I started giving my 12 year old son Probiotic Extra Strength as he has lots of emotional and behavioural problems at school due to low self esteem and anxiety.This has been happening from the moment he started school We are waiting for him to be assessed for Aspergers syndrome.
    To cut a long story short, since he is on the Probiotic (10 weeks now) school life has enormously improved, no uncontrollable outbursts of anger, teachers can 'reason' with him, he has more patients to concentrate.....fantastic! He even stayed 'calm' at the dentist and had a filling done without running away! AMAZING!
    As far as we are aware he has no problems with his gut, never complained of anything relating to digestive problems etc. It would be interesting to hear from other people who have similar experiences.

    From a very happy customer

  • I came across probiotic information by accident while researching gf/cs free diet for my hf 5 year old DS. My son has had symptoms of autism and sensory issues since he began to walk. He walked on tip toes, lined up toys, very intense etc. his symptoms were what I considered mild. Before his first bday he had 4 ear infections. I nursed him and could not understand why. I researched natural remedies for ear infections and found that probiotics helped prevent them. I started with an infant probiotic I found at health food store. He is 5 now and has only had one ear infection since then. Right before he turned 3 I completely stopped giving him the probiotics. He stopped getting ear infections and figured it was time to wean him off. He doesn't get ear infections but his hyperactivity, food texture sensitivities, melt down, difficulty in transitioning and a whole lot more started at this age. My jaw hit the floor when I came across your article I want to run and buy him probiotics right now! I really believe his autistic behaviours increased when I stopped the probiotics. I know I shouldn't get my hopes up but I am really praying this helps. Thanks for your article from an HF mom.

  • Hello,
    My son is almost 11 and he has autism, ADHD, COD, PDD and ODD, but he is high functioning. He doesn't eat all that great( meaning he eats processed foods, but does eat some vegetables). We just started him on a probiotic last night. We think he is full of yeast. He itches his anus somewhat frequently as well as other yeast symptoms. Do you think we need to put him on a enzyme as well? or can you point us in another direction? We have tried the diet thing awhile back and didn't have much luck. Also, his main problem is being argumentative and not accepting no. thanks for any help you can give me..thx,

    Lynne Beatty

  • Hi Lynne,

    Thanks for your email. I can only really advise you regarding the suitability and efficacy of our own range of products and, due to the very complex nature of your son's condition, if you do feel as though he might benefit from additional supplements, then I suggest that you consult a qualified practitioner who can assess his diet, lifestyle and history and make suitable recommendations.
    Check out the BANT website to find a therapist near you.

    Wishing you and your son the best of health.


  • My grandson was born a few seconds too early, breathed in and got pneumonia. Doctors gave him antibiotics and he was in the hospital for 10 days. By the time he was 2 months old, it was obvious he had a problem. His father thought he was blind, but I knew that he could see things, but he didn't look at or interact at all with people. I began doing research and found some that indicated that there might be a relationship between autism and overabundance of yeast in the system. We immediately began to give him baby acidophilus. Within 3 days I dropped in to babysit, and he stared at me as if I were a complete stranger - for 20 minutes straight - until I let him fall asleep. From that point on, he was completely normal. I wrote up the case in my blog.

  • My brother has autism and we began supplementing him with probiotics after reading an article on National Geographic. It agrees with this one and numerous studies that show a link between probiotic supplementation and improved quality of life. Not to say that individuals with Autism are vitcitms of a disease. Quite the contrary, my brother is the happiest kid i know.

    Anyway, if there is anyone looking for a good place to start looking for the best route to get probiotics into the system i'd suggest 1. articles like these. 2. grocery stores (for yogurts, food source of probiotics) 3. supplements. Make sure you read independent reviews though and not biased ones.

  • started giving my non verbal autistic 3 yr old son an all natural probiotic powder that I could easily sneak in his food and drinks....I definitely noticed a difference in his ability to focus and a LOT less stimming. He's saying new words each and every day and I believe it's because his attention is more focused and he's more calm....I can't be certain of course because I can't ask him but the timing certainly isn't a coincidence. I'm happy to share with you what I used but don't want any backlash because as parents of autistic children we know NO two are necessarily alike. Email me at [email protected] and I will definitely respond. Good luck to you all. We absolutely have to be a support system to one another.....that's also where different ideas come from! Trial and error until we find one that works for our child!

  • My 15 year old son who has high functioning ASD has been on probiotics for the last 3 years. I had started him on them after reading reviews like this. I started them in his six weeks school holidays together with omega 3 fish oils 1,000mg high dose. When he started back to school in the September his SENCO and one to one help and teachers all asked what had happened over the holidays as his concentration, social behaviour and overall personality had improved significantly (no more meltdowns). That was after just 6 weeks. He has taken them since and has only had one meltdown in school in last 3 years due to stresses of exams.

  • Response from OptiBac Probiotics

    Hi Dani,

    That's such wonderful news regarding your son - thank you for sharing your experience.

    Warm wishes,

    Customer Care and Nutritional Advisor
    OptiBac Probiotics

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