Gluten-Free, Casein-Free Diet and Autism Ranking:

Bread The gluten-free, casein-free diet (GFCF diet) is designed to exclude all foodstuffs which contain gluten and casein.

Gluten is a protein found in some cereals such as wheat, rye and barley. Oats contain a similar protein called avenin and are usually processed in the same factories, so are often included in the list of foods to be avoided for people following this diet. Casein is a protein found in dairy products such as milk, butter, cheese and yoghurt.

There are several overlapping theories as to why gluten and/or casein may be harmful to some individuals. For example, some people believe that improperly digested gluten and/or casein (in the form of harmful peptides) may adversely affect the central nervous system. Other people believe that gluten and/or casein may provoke adverse autoimmune responses in the gastrointestinal (GI) system.

Some people believe that harmful peptides and/or adverse autoimmune responses may create some of the core features of autism, such as difficulties with social communication and social interaction, alongside related problems, such as challenging behaviours. They also believe that by excluding gluten and-or casein from the diet, they can prevent these problems.

Please note

The National Institute for Health and Care Excellence (2012) made the following observations on the use of exclusion diets for adults on the autism spectrum:

"... there is very little evidence regarding safety and efficacy for exclusion diets ... for the treatment of autism."

The National Institute for Health and Care Excellence (2013) made the following observations on the use of exclusion diets for children and young people on the autism spectrum:

“Do not use the following interventions for the management of core features of autism in children and young people: exclusion diets (such as gluten- or casein-free diets).”

Our Opinion

Eating a healthy, balanced diet is recommended for everybody in order to maintain good health. Anyone with a particular condition (in addition to or separate from autism) may be recommended to follow a special diet by a dietitian and this should be followed on an individual basis. For example, dietitians may recommend a gluten or milk exclusion diet for various gastrointestinal problems.

There is some research to suggest that some autistic individuals may have significant gastrointestinal problems, although the actual number of individuals with GI problems is unclear. There is no scientific consensus on whether autistic ndividuals do or do not have unusual levels of peptides in their bodies.

Determining if gastrointestinal problems or high levels of peptides cause the core features of autism or related problems is not currently possible. We must wait until further research of sufficiently high quality has been completed.

There have been several randomised controlled trials and several single-case design studies into the use of the gluten-free, casein-free diet for autistic people but the results are mixed.

Determining if the GFCF diet has any significant benefits for autistic individuals is not currently possible. We must wait until further research of sufficiently high quality has been completed.

The gluten-free, casein-free diet can involve significant inconvenience and cost, as well as significant limitations on what you can eat. It also poses a number of potential risks including a low intake of calcium, iodine and fibre which can lead to weaker bones, iodine deficiency and gut problems (there is also a risk of masking undiagnosed coeliac disease if a coeliac disease test is not carried out before trialling the diet). Because of this, we cannot recommend its use.

However, because the diet is one of the most commonly used interventions for autistic people we do strongly recommend that further research is undertaken. This research should use more scientifically robust, experimental methodologies with larger numbers of participants. It should also investigate if there are different subsets of autistic individuals (such as those with gastrointestinal problems or those with allergies to gluten and/or casein) who might benefit most from the diet.

Disclaimer

Please read our Disclaimer on Autism Interventions

Audience

The gluten-free diet is usually recommended for individuals who have an allergy to or are sensitive to gluten, including people with coeliac disease (a digestive condition where the small intestine becomes inflamed and unable to absorb nutrients) or dermatitis herpetiformis (a type of skin rash linked to coeliac disease).
The casein-free diet is usually recommended for individuals who have an allergy to or are sensitive to casein.
The gluten-free, casein-free diet is usually recommended for individuals who have an allergy to or are sensitive to both.

A number of people have suggested that there are particular groups of autistic individuals who might benefit from the gluten-free, casein-free diet. For example,

Knivsberg et al (2002) theorised that there is a group of autistic children whose “attention and social indifference was disrupted due to opioid effects caused by peptides from gluten and casein”. They suggested that “On a gluten and casein-free diet the children’s autistic traits would decrease, the children would be more attentive, and in a better position to use their abilities, which we hypothesised could be registered in all areas of development”.
Pennesi and Klein (2012) theorised that “the GFCF diet would be more effective for those children with digestive issues (namely, constipation and diarrhea), compared to those with no digestive symptoms, and for those children with food allergies, compared to those with no food allergies”.
Shattock (1995) has suggested that the diet is likely to be more successful in younger autistic children. “Experience also suggests that the results are more easily demonstrated in younger children. The effects in fully grown individuals appear less impressive”.

Aims and Claims

Aims

The gluten-free, casein-free diet is designed to exclude all foodstuffs containing gluten and casein from the body. According to Christison and Ivany (2006), there are four overlapping theories as to why gluten and/or casein may be harmful to some individuals.

“opioid-related: excess of … opioid peptides may result from abnormal gut production of, and/or leakage of, gluten and casein related metabolites leading to altered CNS … activity
peptidase-related: diminished or altered peptidase activity could lead to abnormal GI leakage of pathogenic peptides, including gluten or casein metabolites
immune dysregulation/autoimmune-related: increased antibodies to dietary proteins similar to gluten and casein may cross react with CNS antigens
gastrointestinal-related: gluten and/or casein may act as a pro-inflammatory stimulus in the gut, contributing to autoimmune responses in the GI mucosa”.

Claims

There have been numerous claims for the gluten-free, casein-free diet as a treatment for autistic people. For example, according to Zhang et al (2013), researchers have reported using “… GFCF diets to increase communication skills (e.g., eye contact, vocalization, echolalia, nonverbal communication social interaction, motor abilities, or cognitive abilities, or to decrease challenging behaviors (e.g., tantrums, pica, self-injury, physical aggression, property destruction, stereotypy, play, food consumption, food rejection, gagging, escape) “.

Notes

Antibodies (protective proteins); antigens (toxic substances); autoimmune (disease caused by antibodies); CNS (central nervous system); GI (gastro-intestinal); mucosa (mucous membrane); metabolites (small molecules produced by metabolic processes); opioid (substance resembling opium); pathogenic (capable of causing disease); peptides (substance containing two or more amino acids); peptidase (enzyme which breaks down peptides into amino acid).

Key Features

The gluten-free, casein-free diet (GFCF diet) is designed to exclude all foodstuffs which contain gluten and casein. The gluten-free diet is designed to exclude only gluten and the casein-free diet is designed to exclude only casein.

If you are following the diet you may prefer to make all of your meals yourself by purchasing gluten and casein-free ingredients. Naturally gluten-free, casein-free foods include meat, fish, fruit and vegetables, rice, potatoes and lentils.

Alternatively you can purchase a wide-range of ready-made meals. However it is important to remember that small quantities of gluten and casein may appear in foodstuffs that appear to be safe. For example, gluten or its derivatives can appear in a wide range of things including biscuits, nuggets and chips, as well as some flavourings.

If you are following the GFCF diet, you should ensure that the rest of your diet is healthy and well-balanced. For example, you may need to eat foodstuffs or take dietary supplements that provide alternative sources of calcium, iodine and fibre.

Because it can be difficult to balance a GFCF diet, we strongly recommend that you seek advice from a responsible health professional such as a health visitor or GP. This may lead to a referral to a dietitian – in particular one with experience of working with autistic individuals.

Some experts, such as Martinez-Barona et al (2017), have warned that substituting every day food with gluten-free foods could increase the risk of obesity, after finding that such products often contain higher levels of fats than the food they replace.

Cost and Time

Cost

The major cost of following the gluten-free casein-free diet is buying gluten-free and/or casein-free foodstuffs, which are often more expensive than foodstuffs which contain them. For example, according to Stevens and Rashid (2008), gluten-free products were on average 242% more expensive than regular gluten-containing products.

The actual cost will also depend on whether the whole family is following the diet (which is common) and on whether you are buying ready-made meals or making them yourself.

In the UK, it is occasionally possible to obtain prescriptions for foodstuffs for patients in specific circumstances, such as when they have a confirmed diagnosis of coeliac disease. In many areas of the UK these prescriptions are either being stopped altogether or reduced. Prescriptions for GFCF foodstuffs would not be made for someone on the basis of their autism diagnosis alone.

Time

The gluten-free, casein-free diet is designed to be followed seven days a week. The actual amount of time you need to spend each week will depend on whether you are making all of the meals yourself and also how long it takes you to check the labels of foods you buy to ensure that they do not contain restricted foodstuffs.

Some supporters of the gluten-free casein-free diet recommend that you trial the diet for a period of three or four months. If it has not worked within that time they say it is unlikely to do so. Some researchers suggest that the most reliable trial results are obtained after you have been on the diet for more than a year.

However, most dietitians recommend that a 2-6 week trial of an exclusion diet followed by reintroduction is adequate to identify if a dietary change has been beneficial. This is backed up by the 2011 NICE guideline ‘Food allergy in under 19s: assessment and diagnosis’ that recommends “if non-IgE)-mediated food allergy is suspected, trial elimination of the suspected allergen (normally for between 2–6 weeks) and reintroduce after the trial. Seek advice from a dietitian with appropriate competencies, about nutritional adequacies, timings of elimination and reintroduction, and follow-up”.

Risks and Safety

Hazards

There are many potential risks to withdrawing normal or regular foods, especially from young children. For example,

According to Shattock (1995), “Initially the reported effects may be negative. Upset stomach, anxiety, clinginess, dizziness, aches and pains and slight ill-temper have all been reported”, although he also notes “Experience would suggest that these are good signs and precursors of a positive response”.
According to Connor Z (2014), ”The gluten-free, casein-free diet also poses a number of potential risks including a low intake of calcium, iodine and fibre which can lead to weaker bones, iodine deficiency and gut problems (there is also a risk of masking undiagnosed coeliac disease if a coeliac disease test is not carried out before trialling the diet)”.
According to Mari-Bauset et al (2015), “The combination of food selectivity and restrictive diets can make it difficult to achieve an adequate diet, consequently resulting in an excessive intake of certain foods and/or deficiencies and malnutrition due to insufficient amounts of other foods. In turn, inadequate intakes may lead to the development of chronic and degenerative conditions that tend to appear in the third or fourth decade of life (cardiovascular disease, high blood pressure, diabetes, dyslipidemia, and osteoporosis, among others) or even earlier, in the case of menstrual disturbances, sleep apnoea, and psychosocial disorders”.

Contraindications

There are no known contraindications (something which makes a particular treatment or procedure potentially inadvisable) for the gluten-free, casein-free diet.

However, some autistic people eat only a limited range of food. They already have a less healthy and less varied diet than other people. Restricting what they eat even further may reinforce those rigid eating patterns. It may also increase their social isolation (because they can’t eat the same food as their peers at parties or restaurants).

If you have concerns about your own diet or your child's diet you should seek advice from a responsible health professional such as a health visitor or general practitioner (GP). This may lead to a referral to a dietitian – in particular one with experience of working with autistic individuals.

Suppliers and Availability

Suppliers

Gluten-free, casein-free foodstuffs (including ingredients and ready-made meals) are available from a wide range of suppliers (such as chemists and supermarkets) in the UK, the US and some other countries. Most (but not all) foodstuff labels state whether they contain gluten and/or casein.

Various support groups also produce advice about food content, gluten- and casein-free foods, together with special GFCF cookery books etc.

Credentials

There are no formal qualifications for people using the gluten-free, casein-free diet since any individual, parent or carer can choose to follow the diet.

However, if you are contemplating such a significant change of diet, we recommend that you should seek advice from a responsible health professional such as a health visitor or GP. This may lead to a referral to a dietician – in particular one with experience of working with autistic individuals.

The British Dietetic Association has information about qualified dietitians in the UK.

Related Suppliers and Availability

History

In the early 1980s a number of researchers, including Herman and Panksepp, noted the similarities between the effects of opioids and the symptoms of autism. Panksepp suggested that autistic people might have high levels of opioids in their central nervous systems.

Subsequent research reported that some autistic people have abnormally high levels of peptides in their bodies, although this has since been disputed. Thereafter some professionals and parents began to use the gluten-free, casein-free diet in order to eliminate these peptides.

Current Research

We have identified more than 20 scientific studies of the gluten-free, casein-free diet for autistic people published in English-language, peer-reviewed journals.

The published studies included a total of 200 plus individuals aged from 2 years old to adult with a variety of diagnoses including autism, autistic disorder and pervasive developmental disorder (not otherwise specified).

The majority of the studies examined the gluten and casein-free diets together, sometimes compared with no treatment or placebo.
One study (Nazni et al 2008) compared the gluten-free diet with the casein-free diet and with the gluten-free, casein-free diet.
One study (Reichelt 1990) compared the gluten-free diet with a restricted gluten-free diet.
Two studies (Bird et al 1977; Johnson et al. 2011) compared the gluten-free and/or casein-free diet to other interventions (a behavioural intervention; a low sugar diet).
One study (Lucarelli 1995) examined the removal of cow milk protein.
The majority of the studies (16) reported significant improvements in areas such as the core symptoms of autism, gastrointestinal problems, and challenging behaviours
One study reported mixed results and seven studies reported no significant improvements

Please note: we have not included any studies in which the gluten-free, casein-free diet was provided as part of a multi-component package alongside other treatments (such as chelation). Nor have we included any studies in which a wide range of foodstuffs (not just casein and gluten) were excluded at the same time.

Status Research

Studies

There are a number of limitations to all of the research studies published to date. For example

The majority of studies (12) used single-case designs (such as case studies, ABAB or pre-test post-test designs) and six of these reported on a single participant.
Three of the randomised controlled trials (Navarro et al, 2015; Hyman et al, 2016, Elder, 2006) had fewer than 20 participants. One of these studies (Navarro et al, 2005) had only six participants.
One of the studies (Pusponegoro et al, 2007) had very high levels of participant drop out (almost 30%), meaning the results could be more open to bias.
Some of the studies (such as such as Kinivsberg et al, 2002) did not provide enough details about the participants (such as whether they had a formal diagnosis of autism), meaning it is not clear if the diet would work for other people diagnosed with autism.
Some of the studies (such as Knivsberg et al, 2003) restricted the participants to those with unusual biochemical profiles (such as those with abnormal urinary peptides) meaning that the results cannot be generalised to autistic people who do not have those unusual profiles.
Some studies (such as Elder et al, 2006) did not restrict the participants to those with unusual biochemical profiles meaning (according to some supporters of the diet) that the diet could not have worked, since it is only designed to work on individuals with those profiles.
One of the controlled studies (Nazni et al 2008) was non-randomised and non-blinded, meaning the results could be more open to bias.
One of the studies (Pusponegoro et al 2007) lasted no more than a week, meaning that there may not have been time for any effects of the diet to appear.
Some of the studies (such as Cade et al 1999) lasted for more than a year, mearing that any effects could have been caused by a range of other factors, including the normal development of the participants.
Some of the studies which used a crossover design (such as Elder et al, 2006) did not include a wash-out period. This means that those participants who received the placebo after the diet could have still been showing the effects of the diet when they received the placebo.
Some of the studies (such as Reichelt, 1990) provided no information on how strictly the diet was implemented. Some studies (such as Johnson et al, 2011) reported that some of the participants struggled to adhere to the diet. In both cases, this could mean that the outcomes reported may not be valid.
Some of the studies (such as Lucarelli et al, 1995) eliminated other, unspecified foodstuffs from the diet and some of the studies (such as Reichelt, 1990) included medications in the treatment, meaning it is difficult to know what caused any of the reported effects.
Some of the studies (such as Cade et al, 2000) incorporated non-standard assessment tools used by lay raters (such as parents) meaning the reported outcomes could be less valid.
Some of the studies (such as Whitely et al, 1999) had incomplete or partial outcome data (such as ratings by teachers) meaning it is difficult to interpret those data accurately.
Three groups of researchers each published two different papers reporting on the study that they had carried out (Elder 2007 and Seung et al 2007; Knivsberg et al 2002 and Knivsberg et al 2003; Whitley et al, 2010 and Pedersen et al, 2014), meaning that care has to be taken not to count the results twice.

For a comprehensive list of potential flaws in research studies, please see ‘Why some autism research studies are flawed’

Scientific Reviews

There have been a number of scientific reviews of the gluten-free, casein-free diet as an intervention for autistic individuals. The majority of these have concluded that there is insufficient evidence to determine if the diet is effective for autistic people. For example, Mari-Bauset et al (2014) noted that

“Methodologic limitations identified were associated with a range of factors: the lack of a control group and/or clear definitions of inclusion criteria, very small sample sizes, and analysis being based on single individuals or anecdotal information, groups being heterogeneous in terms of age, failure to control for phenotypic variability between individuals, interventions being of variable duration and generally short, as well as lack of preintervention postintervention comparisons. There was also a risk of bias in data on the behavioral variables attributable to memories of parents and other caregivers being distorted over time and that their perception of changes in the behavior of participants can be subjectively influenced by the fact of being included in nonblinded trials. Similarly, a placebo effect could have had an impact on the results. Lastly, alternative explanations were not always considered, such as the risk of confounding bias, in particular, it being possible that behavioral improvements were due to ongoing development and behavioral therapy given, rather than to gluten-free, casein-free diets per se”.

Ongoing Research

Massachusetts General Hospital is running a trial of a gluten- and casein-free diet. Clinical Trials Gov Ref: NCT01116388. For more details, please see Study to Assess the Role of a Gluten Free-dairy Free GFCF Diet in the Dietary Management of Autism Associated Gastrointestinal Disorders Full Item (Open in new window)
Medical University of Warsaw is running a study to evaluate the impact of gluten challenge on the autistic symptoms in children with autism spectrum disorders (ASD) and on a gluten-free diet (GFD) in comparison to individuals continuing GFD. Clinical Trials Gov Ref: NCT02280746. For more details, please see Gluten for Autism Spectrum Disorders Full Item (Open in New Window)

Future Research

Summary of Existing Research

There is some research to suggest that some autistic individuals may have significant gastrointestinal problems, although the actual number of individuals with GI problems is unclear. There is no scientific consensus on whether autistic individuals do or do not have unusual levels of peptides in their bodies.