Autism & Diet 2: Why Autism Parents are Drawn to Special Diets

Behavior of many children with autism fluctuates from hour to hour and day to day due to numerous factors. Some mornings when the child slept poorly the night before, the youngster may be more irritable. For an hour or more after a child was involved in a fracas with her sibling she may be prone to a meltdown. If the child’s school had a fire drill earlier in the day, s/he may be upset the remainder of the day. If a child is frustrated because there has been a chan
ge in his daily routine she may also have a meltdown. This morning your daughter has had two sippy cups of apple juice and some fresh pear for a snack, and has experienced a tummy ache and loose stool. Oh, and I almost forgot, she inadvertently ate an oatmeal cookie that contained gluten last night before bed. Which is the cause of their child’s behavioral irritability and bowel problem? It is impossible to know since many things change from day to day that can contribute to similar symptoms. Parents focus on what they think is most likely to be causally important. If they believe the gluten in her diet contributes to her behavior problems and loose stools, that is what they will remember and they may disregard the rest.

Typical Dietary Habits of Children with Autism

Most studies show children with autism are finicky eaters and seldom have a balanced diet. I have summarized here findings from several studies: “ASD children tend to consume less vegetables, salad and fresh fruit. Nutrients least likely to be consumed in their diets in recommended amounts were vitamin A, vitamin E, fiber, and calcium.” “Intake of total calories, carbohydrates, and fat are typically in the average range; protein intake was increased (211% of RDA). Reported frequency of GI abnormalities, including abnormal stool consistency (e.g., bulky or loose), was increased (54%), but there is no statistically significant relationships between stool consistency and dietary intake.” In one study of enlarged colon among some children with autism, increased constipation and colon size was associated with excessive cheese and milk consumption. In another study, constipation or diarrhea were as common among children with other developmental disability as among children with autism, suggesting GI problems are not autism-specific.

Importance to Parents of Identifying a Tangible Autism Cause

If parents believe their child’s autism was caused by a vaccine that had been administered by the child’s doctor, that makes it possible to point to a single, visible, tangible cause of their child’s condition, much as they might point to eggs tainted with salmonella causing food poisoning. It is comforting to know what causes a person’s symptoms. From the day their child was first diagnosed, parents want to know what caused their child’s disability. To be told autism is usually of genetic in origin seems ethereal to parents, conjuring up images of squiggles of DNA too small to be seen by a microscope, which might as well be black holes in a distant galaxy. In fact, DNA is no less real, but it may seem less tangible to parents because they are unable to see it and hold it in their hands.

If parents can say, “That thing over there
(pointing with their index finger to the vaccine vial in the doctor’s office) caused my child’s autism,” that means their feelings of guilt and blame regarding their child's diagnosis are diminished because they can hold accountable the doctor who injected the MMR vaccine, or the pharmaceutical manufacturer who created the vaccine that placed it into injection vials. “There is nothing I did that caused my child’s autism. I trusted the doctor and now see what has happened!” the parent thinks. It makes sense that this scenario is highly appealing to parents, but it appears the link between vaccine and autism is false. I’m reminded of Lewis Carroll’s, The Hunting of the Snark, in which a cast of unlikely compatriots whose names all begin with the letter B, head to sea in search of the mysterious beast, the Snark. At the end of the epic poem, the Baker calls out that he has finally found a Snark; but when the others arrive to witness the elusive Snark first hand, he has mysteriously disappeared, 'For the Snark was a Boojum, you see'. The leaky gut claimed to be the result of MMR vaccine was also a Boojum, you see.

Diet: Something Fairly Simple Parents Think Might Help

A child’s bowel problems and tummy ache are tangible to parents. The notion that they are produced by diet or a vaccine is appealing. There is a clear causal arrow between A and B. Bowel movements are something real, to which anyone who has been parent of a young child in diapers can attest, me included. Parents can see and point to signs of the problem, and more importantly, there are specific things they can do that they think will improve the child’s autism symptoms, or at least they believe they can. They can switch their child to a casein-gluten free diet, which is far simpler than taking part in many hours per week of home-based early intensive behavioral intervention. The fact that their child’s autism symptoms resulted from differences in the way several of his brain structures developed, that one can only see with a brain imaging scan (if then), makes the causes intangible and less real to parents. Parents wonder, “But what can I do to fix my child’s brain?” They can usually do a great deal, by implementing an intensive early behavioral intervention program that promotes new connections in those dysfunctional brain structures. But to skeptical parents, that all seems very abstract with results far off in the distant future. They think, “Perhaps a CGFD will produce immediate improvements.”

Should Parents Try The CGFD?

If, as has been reviewed above, there is limited evidence of the effectiveness of a CGFD, should parents give it a try anyway? In my own conversations with parents I find some who are convinced the CGFD diet has been helpful and others who report they could see no difference and stopped using the diet. Are there reasons parents should not try the CGFD for their child? There are things to consider in deciding to try the diet.

• Many children dislike the flavors and consistency of CGFD, foods and it can be a struggle to induce them to eat it. Some parents eventually give up.
• t can be costly, especially if parents purchase mostly prepared foods.
• It is inconvenient when their child’s peers may be consuming far more appealing foods at school and in the community than the child with autism is allowed to have.
• The CGFD and most other alternative interventions are not evidence-based. Parents often feel compelled to defend their use of the diet, even when they realize there is little objective evidence they are helpful. That leads them down the path of untested treatments.
• Emphasis on the diet tends to diminish the importance parents place on effective early behavioral intervention. If parents believe the diet will take care of their child’s autism symptoms, why waste their time and money on early intervention. A study by Corina Grindle and colleagues in the UK indicated lack of commitment to an effective early ABA program while parents tried various other interventions, predicted an unfavorable child outcome.

Evidence-Based Enemies

Some parents view as miscreant enemies, professionals like me who point out there is very little evidence from controlled studies supporting the use of the CGFD in autism. If immunization did not trigger the gut changes that require the CGFD, then what are parents to believe? That raises the possibility that the special diet they have been giving to their child isn’t really necessary or helpful. That leads them to think that perhaps they should be trying something altogether different. Maybe it was something else we did that caused our child’s disability. The answer is almost certainly that IT IS NOT something else a parent did that led to autism. Some types of autism are caused by unpredictable, chance genetic mutations, and it appears other factors may play a role among some susceptible people. But false prophets (Offit, 2008), like Johann Guggenbuhl, do not give up their claims easily, especially when large amounts of money and personal prestiege are at stake. But because a nostrum is ineffective, should not lead parents to despondency, because there are other highly effective, albeit more demanding, alternatives. It is just that there is unlikely to be any quick fixes.

Conclusions: Diet and Autism

1. Most children with autism are finicky and do not eat a balanced diet. They tend to avoid vegetables and fruit and eat twice as much protein as recommended. Vitamin A, E and calcium deficiencies are common. Despite these dietary indiscretions, most children with autism are healthy.

2. Parents’ preparing specialized meals that the child will eat with minimal resistance may inadvertently contribute to dietary deficiencies and aggravate the child’s rejection of a range of foods. Parent cajoling and attention to food resistance may inadvertently reward rejecting new or differing foods.

3. Excessive fruit juice (apple, pear, apricot, cranapple) can cause diarrhea. Excessive milk, meat and cheese can contribute to constipation.

4. Parent surveys indicate 40-60% of children with autism experience gastrointestinal problems (diarrhea, reflux or constipation). Surveys of typical children report smaller percentage of GI problems, but these autism percentages are similar to those of children with other neurodevelopmental disabilities.

5. Many parents of children with autism report their children have food allergies, but when actually tested about the same percentage have food allergies as typical peers (9%).

6. Gluten sensitivity (celiac disease) among children with autism is about the same prevalence as same age children without autism (1%). A much larger proportion of children with autism are given the CGFD by their parents.

7. There have been 3 randomized clinical trials with a CGFD in autism revealing some improvements in several subscales in two of the three clinical trials, none in the third trial and no improvements in other subtests. An American Consensus Panel convened in 2009 concluded there was insufficient evidence to indicate the CGFD was effective.

8. Parents may conclude specialized diets, like the CGFD are useful for their children because it is something concrete they can do that might improve their child’s functioning. Since no data are maintained regarding diet in most families, GI and behavioral symptoms, there is generally no way of knowing whether the diet is helpful, and therefore cannot be easily disproved. In such cases, parents have to decide whether it is worth the cost and effort to feel they are at least “doing something.”

9. Most other effective interventions, such as intensive early behavioral intervention, require long term commitments with gradual improvements in child symptoms over time, making dietary treatments appealing because they seem to promise more immediate gains with less effort and time commitment.


Buie, T. et. al. (2010) Evaluation, diagnosis, and treatment of gastrointestinal disorders in individuals with ASDs: a consensus report. Pediatrics. 125 Suppl 1:S1-18.

Carroll, L (1914)
The hunting of the Snark: An agony in eight fits; with Illustrations by Henry Holiday. New York: McMillan & Company.

Cass H. et. al. (2008) Absence of urinary opioid peptides in children with autism. Arch Dis Child 93:745-50

Elder, JH. Et. al. (2006) The gluten-free, casein-free diet in autism: results of a preliminary double blind clinical trial. J. Autism Dev Disord. 36:413-20,

Elder, JH (2009) The gluten-free, casein-free diet in autism: an overview with clinical implications. Nutr Clin Pract 23:583-8.

Emond, a. (2010) Feeding symptoms, dietary patterns, and growth in young children with autism spectrum disorders. Pediatrics. 126(2):e337-42

Hendy, HM (2010) Parent mealtime actions that mediate associations between children's fussy-eating and their weight and diet. Appetite. 54: 191-5.

Horvath, K, et. al. (1998) Improved social and language skills after secretin administration in patients with autistic spectrum disorders. J. Assoc. Acad.Minor Phys. 9:9-15.

Jyonouchi, H. (2005) Dysregulated innate immune responses in young children with autism spectrum disorders: their relationship to gastrointestinal symptoms and dietary intervention. Neuropsychobiology 51:77-85.

Levy, SE et. al. (2007) Relationship of dietary intake to gastrointestinal symptoms in children with autistic spectrum disorders. Biol. Psychiatry 61:492-7.

Offit, P.A. (2008) Autism’s false prophets: Bad science, risky medicine and the search for a cure. NY: Columbia University Press.

Lockner, DW (2008) Dietary intake and parents' perception of mealtime behaviors in preschool-age children with autism spectrum disorder and in typically developing children. J. Am. Diet. Assoc. 108:1360-3.

Millward, C. (2008) Gluten- and casein-free diets for autistic spectrum disorder. Cochrane Database Syst. Rev. Apr 16 (2) CD003498

Smith, RA. Et. al. (2009 Are there more bowel symptoms in children with autism compared to normal children and children with other developmental and neurological disorders?: A case control study. Autism. 13:343-55.

Sturmey, ,P. (2005) Secretin is an ineffective treatment for pervasive developmental disabilities: a review of 15 double-blind randomized controlled trials. Res. Dev. Disabil. 26:87-97.

Thompson, T, (2007) Caveat Emptor: Cautionary Consideration for Parents and Practitioners. Chapter 10. In T. Thompson, Making Sense of Autism. Pg 187-203.
Baltimore: Paul H. Brookes Publishing Co.

Wakefield, AJ et. al. (1998) Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children. Lancet 351: 637-41.

Whiteley P, et. al (2010)The ScanBrit randomised, controlled, single-blind study of a gluten- and casein-free dietary intervention for children with autism spectrum disorders. Nutr Neurosci. 13:87-100