Most parents of children on the Autistic Spectrum have heard about, if not tried implementing, a Gluten-Free (GF) or Gluten-Free, Casein-Free (GF-CF) Diet. By contrast, official dietary guidelines and most mainstream health practitioners say there’s no good evidence that a GF-CF diet (or any other kind of dietary intervention) – has any benefits for Autistic Spectrum Disorders (ASD). This brief article attempts to clarify what is a complex and confusing subject, and also provides suggestions for further reading.
First, ‘adverse food reactions’ are very individual. They can occur in response to almost any food or ingredient, and for many different reasons, including:
- food poisoning (from spoilage or contamination);
- difficulties in metabolism and breakdown of particular substances found in some foods.
- ‘classic’ allergies – i.e. immune-mediated reactions involving specific antibodies (‘IgE’)
- other forms of ‘food intolerance’ for which mechanisms are not fully understood (but which may depend on both quantities consumed, and general gut health).
Adverse reactions to gluten (a protein compound found in wheat and many other grains) are among the most common in the general population, as are allergies to cows’ milk, in which casein is a major protein (albeit not usually the ‘target’ for classic milk allergy).
Research evidence shows that gluten and/or casein can trigger, or exacerbate, both physical and mental symptoms in some people with ASD and other developmental or mental health conditions. However, ASD is not a unitary condition, and much of the controversy over whether or not GF-CF diets can be ‘beneficial for ASD’ arises from mistakenly regarding it as such, as discussed further below.
As with food poisoning, not all ‘adverse food reactions’ require permanent avoidance of the food in question (although if severe, such experiences may lead to psychological and behavioural aversion). If inefficient metabolism of particular substances is to blame, then simply limiting the quantities consumed can prevent re-occurrence.(1) Similarly, if gut inflammation and/or ‘dysbiosis’ (an unhealthy gut microbial balance) is an issue, then reducing these may ameliorate symptoms (and is a good idea in any case). Even classic allergies can resolve with age (although safety precautions should always be taken with these).
Focusing first on gluten, adverse reactions may occur for at least three distinct reasons, only one of which involves mechanisms that may also explain similar adverse reactions to cows’ milk.
Classic allergy to wheat
Some people who react badly to grain-based products actually have a classic (IgE-mediated) allergic reaction to other proteins in wheat, rather than gluten itself. If so, a much less restrictive diet may alleviate symptoms, as gluten is found in (and added to) a very wide range of foods and drinks.
Coeliac disease – a gluten-triggered autoimmune disorder
Coeliac disease (CD) is a genetically-mediated auto-immune disease, affecting at least 1% of the population, although many cases go undetected. In predisposed individuals, gluten exposure can trigger the production of auto-antibodies that damage the intestinal lining and impair nutrient absorption.
Classic CD symptoms therefore include ‘failure to thrive’, stunted growth or other malnutrition symptoms, and gastrointestinal (GI) symptoms. The only treatment for CD is a strictly gluten-free diet.
In many cases – often called ‘silent coeliac’ – classic symptoms are mild enough that CD goes unsuspected, despite auto-antibodies having been triggered. These can affect the brain and nervous system (as they can in overt CD), leading to mood and behavioural symptoms resembling anxiety, ADHD, ASD, depression or even psychosis,(ii)and/or neurological symptoms such as poor balance and co-ordination (3).
Individuals with ASD or ADHD have an elevated risk for CD, although testing for this is not routine for these conditions(4). However, in anyone with family history of CD, GI symptoms and/or any other psychiatric or neurological symptoms, screening may be worthwhile.
Importantly, testing for CD must be done before adopting gluten-free diet as diagnosis relies on detecting auto-antibodies – known as tissue transglutaminase (TTG) – triggered by gluten exposure.
Non-Coeliac Gluten Sensitivity (NCGS)
While objective tests exist for wheat allergy and CD, the same is not true of other forms of gluten intolerance – collectively known as ‘Non-Coeliac Gluten Sensitivity’ (NCGS). This usually involves:
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- Mental symptoms like anxiety, depression, mood swings, other psychiatric or neurological symptoms (including psychosis), and cognitive problems often described as ‘brain fog’ (involving poor attention and memory and low mental energy or fatigue)
- GI symptoms such as ‘indigestion’, gut pain, bloating, constipation, diarhhoea and/or ‘irritable bowel syndrome’ (IBS).
Increasing evidence indicates that ‘NCGS’ is not a single syndrome, but instead encompasses several different conditions – some reflecting intolerance not to gluten, but to other substances often found in the same foods.
However, adverse reactions to gluten itself may occur via various ‘non-coeliac’ mechanisms.
First, gluten is a mild ‘irritant’ to the gut lining, and while most people may be able to deal with this,[i] others (with NCGS) experience GI and/or mental symptoms.[ii] Vulnerability to gluten sensitivity may therefore involve pre-existing gut inflammation and/or a ‘leaky gut’. Both can be aggravated by gut dysbiosis (particularly yeast infections), and by diets high in ultra-processed foods (UPF) (which typically contain excessive sugar, many artificial additives and a pro-inflammatory balance of fats). Some common medications – including antibiotics, aspirin and NSAIDs can also irritate or damage the gut lining.
So, if gut inflammation or damage is present, and/or if gluten is consumed in excessive amounts, this may increase intestinal permeability, which has been implicated in ASD and related conditions.[7][8]
Furthermore, many children with these conditions do consume large amounts of gluten (and casein), not least because foods containing these are often the very foods they most crave (and for many highly selective eaters, they often make up the majority of their diet). Why might this be?
One possible explanation for strong cravings for gluten or casein (and also ‘withdrawal’ symptoms) concerns ‘opioid-like’ effects. Digestion of gluten gives rise to specific peptides (protein fragments) called ‘gliadomorphins’ – which activate the same receptors as morphine and other opioid drugs. Importantly, similar ‘opioid peptides’ – known as ‘casomorphins’ – are also released in the digestion of beta-casein. This protein is found in all animal milks (including human breastmilk), but the ‘A1’ form is found only in cows’ milk – and this gives rise to a particularly powerful opioid peptide, beta-casomophin-7 (BCM-7). Consumption of A1 rather than A2 beta-casein has been linked with a wide range of health issues affecting gut, immune system and brain function, although clinical trial evidence of causal effects remains limited.[9]
‘Opioid’ theories of both ‘Autism’ and ‘Schizophrenia’ have a long history – based on
(1) theory – many clinical features of both conditions are consistent with ‘opioid excess’
(2) biochemical evidence – consistent with reduced breakdown of the opioid peptides released by digestion of gluten or casein
(3) apparent sensitivity of at least some individuals with these labels to BOTH gluten AND casein, as evidenced by improvements in mood and behaviour on a GF-CF diet.
Clinical Trials of GF-CF Diets ‘for’ ASD
In children with ASD, clinical studies of GF-CF diets – including some randomised controlled trials (RCT) have yielded mixed results. Studies have been small, using different designs – and often additional treatments. Other limitations include the fact that full double-blinding of real diets is never possible, and maintaining compliance is particularly difficult with this kind of population, as anxiety around unfamiliar foods and/or selective eating is an issue for many children with ASD. For these reasons, the ‘solid’ clinical evidence of benefits from RCTs and systematic reviews that official treatment guidelines require remains lacking.
Nonetheless, the clinical trial evidence does consistently indicate that GF-CF diets may alleviate some symptoms in at least some individuals with ASD and related conditions.[10][11] Thus a systematic review of RCTs of the GF-CF diet for ASD children with ASD[12] (which did not recommend such diets, except in cases of ‘confirmed allergy’) included the following summary:
“In a recent UK survey, more than 80% of parents of children with autism spectrum disorder reported some kind of dietary intervention for their child (gluten-free and casein-free diet in 29%).
When asked about the effects of the gluten-free and casein-free diet, 20-29% of the parents reported significant improvements on the autism spectrum disorder core dimensions.
The findings of this study suggest additional effects of a gluten-free and casein-free diet on comorbid problems of autism such as gastrointestinal symptoms, concentration, and attention.
The findings of another recent investigation suggested that age and certain urine compounds may predict the response of autism symptoms to a gluten-free and casein-free diet. Although these results need to be replicated, they highlight the importance of patient subgroup analysis.
Intervention trials evaluating the effects of a gluten-free and casein-free diet on autistic symptoms have so far been contradictory and inconclusive.”
The reports from parents surveyed may of course simply reflect ‘placebo’ effects – but experienced clinicians and parent support groups do consistently report that around 20-30% of ASD children appear to benefit from a GF-CF diet. As this is only a minority, results for this subgroup will be outweighed by those of ‘non-responders’ in any studies that base their inclusion criteria only on the ASD diagnosis – which is well known for its heterogeneity. The challenge for researchers and clinicians is therefore to find out which individuals and ‘subgroups’ might benefit, and how best to identify them (other than by trial and error).
Risks of GF-CF Diets?
In addition to the practical difficulties and potential costs involved, a strict GF-CF diet – excluding all products containing either gluten or dairy milk – can seriously increase risks for nutritional deficiencies or imbalances unless it is very well-planned; so dietary advice and supervision from suitably qualified professionals is needed, with supplementation of essential nutrients if necessary.[13][14][15]
Gluten is found in – or added to – a large number of common foods, although the availability of gluten-free options has increased significantly in recent years. However, many of these are ultra-processed and high in sugar, unhealthy fats and artificial additives. Naturally gluten-free whole or minimally processed real foods are therefore preferable where possible
Importantly, some individuals who cannot tolerate standard cows’ milk can consume goats’ or sheep’s milk products (which do not give rise to such powerful opioid peptides). These provide significantly more key nutrients than plant-based milk substitutes (which are again ultra-processed).
If you require one to one assistance to help support your or your child’s dietary needs, please contact one of our registered nutritionists who will be happy to assist you:
Further information
For information on coeliac disease and related conditions, and gluten https://www.beyondceliac.org/
For more information on A1 and A2 milk:
For further informationon gut health, please see our blog articles:
References
[1] Emsley, J., & Fell, P. (1999). Was It Something You Ate? Food Intolerance: What Causes It and How to Avoid It Oxford University Press (OUP).
[2] An Autoimmune Reaction to Gluten May Cause Childhood Anxiety
[3] Cognitive Deficit and White Matter Changes in Persons with Celiac Disease: a Population-Based Study. Croall et al (2020), Gastroenterology, 158(8) 2112-2122.
[4] Celiac Disease Is Associated with Childhood Psychiatric Disorders: A Population-Based Study. Butwicka et al 2017 – Pediatrics, 184: 87-93
[5] Croall et al. (2019). Gluten Does Not Induce Gastrointestinal Symptoms in Healthy Volunteers: A Double-Blind Randomized Placebo Trial. Gastroenterology, 157(3), 881–883.
[6] Biesiekierski et al. (2011). Gluten Causes gastrointestinal symptoms in subjects without celiac disease: A double-blind randomized placebo-controlled trial. American Journal of Gastroenterology, 106(3), 508–514
[7] Esnafoglu, et al (2017). Increased Serum Zonulin Levels as an Intestinal Permeability Marker in Autistic Subjects. The Journal of Pediatrics, 188:240-44.
[8] Asbjornsdottir et al (2020). Zonulin‐dependent intestinal permeability in children diagnosed with mental disorders: A systematic review and meta‐analysis. Nutrients, 12(7), 1–27.
[9] A1 and A2 Milk Protein – News and Research
[10] Kidd PM. Autism, an extreme challenge to integrative medicine. Part 2: medical management. Altern Med Rev a J Clin Ther. 2002;7(6):472–99.
[11] Whiteley P. Nutritional management of (some) autism: a case for gluten- and casein-free diets? Proc Nutr Soc. 2015 Aug 14;74(3):202–7.
[12] Lange KW et al, 2015. Gluten-free and casein-free diets in the therapy of autism. Curr Opin Clin Nutr Metab Care, 18(6):572–5.
[13] Cornish, E. (2002). Gluten and casein free diets in autism: a study of the effects on food choice and nutrition. Journal of Human Nutrition and Dietetics the Official Journal of the British Dietetic Association, 15(4), 261–269.
[14] Herndon, A. C., DiGuiseppi, C., Johnson, S. L., Leiferman, J., & Reynolds, A. (2009). Does nutritional intake differ between children with autism spectrum disorders and children with typical development? Journal of Autism and Developmental Disorders, 39(2), 212–222.
[15] Marí-Bauset, S., Llopis-González, A., Zazpe, I., Marí-Sanchis, A., & Suárez-Varela, M. M. (2016). Nutritional Impact of a Gluten-Free Casein-Free Diet in Children with Autism Spectrum Disorder. Journal of Autism and Developmental Disorders, 46(2), 673–684.
Disclaimer: The views and opinions expressed in this blog post are those of the author and do not necessarily reflect the official policy or position of any professional organization or guidelines. The information provided is for educational and informational purposes only and is not intended as a substitute for professional advice, diagnosis, or treatment. Always seek the advice of your therapist or other qualified health provider with any questions you may have regarding a medical or mental health condition.