Nutritional and dietary approaches to the management of autism – Dr Janice Joneja

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Autism is a lifelong developmental disorder affecting as many as 1 in 50 children in the USA (Center for Disease Control 2013), 1 in 100 in the UK and as low as 1.1 in every 10,000 in China. Typically children with autism have difficulty with language, communication, and socialisation. They have problems in learning and display a variety of atypical behaviours. The disorder is accompanied by mental retardation in three out of four cases. Asperger’s syndrome (autism without retardation) is included in the range of different presentations of autism. (1)

The number of cases of autism has noticeably risen in recent years. It is unclear whether this is a result of an increasing awareness of autism spectrum disorders, a change in the way that autism is diagnosed so that cases that were not previously recognized as autism are now included under the diagnosis, or a real rise in the number of cases.

Diagnosis of Autism

The diagnosis of autism is usually determined when the child is 2 to 3 years old after extensive evaluation according to the criteria of the Diagnostic Statistical Manual IV (DSM-IV). (2) Sometimes there is evidence of the condition soon after birth as the child does not meet the expected developmental milestones. In other cases the child loses newly acquired skills such as language, eye-to-eye contact, and sociability after a period of apparently normal development. The latter pattern is often referred to as regressive autism and occurs in about one-third of autistic children. (3)

Causes of Autism

There seem to be several different causes for autism, none of which are completely understood. Most authorities agree that there is a strong genetic factor in the condition, and it is not uncommon to see several children, usually boys, with the condition
in the same family. However, the cause of the disorder for the great majority of autistic individuals has not been determined.

It is likely that there are different causes and different precipitating factors associated with the way that autism is experienced by different individuals. The term “autistic syndrome” is often used to describe a pattern of similar behaviors produced by a variety of triggers. (4)

Digestive Tract Disturbances in Autism

Children with autism seem to have a higher incidence of digestive tract symptoms than children without autism. Anecdotal reports by parents extending back more than 30 years described evidence that their autistic children had disturbed gastro­intestinal (GI) tract function, citing symptoms such as abdominal pain, bloating, constipation, loose stools, and frequent diarrhea. (4) A survey of 500 parents of autistic children carried out in 2001 showed that almost one-half reported that their chil­dren had loose stools or frequent diarrhea. (5) Parents frequently reported an apparent intolerance to certain foods, especially wheat and cow’s milk.

Several studies have demonstrated abnormal digestive tract function in autistic children. A leaky gut (increased permeability of the membrane lining the digestive tract, which allows food molecules that would normally be excluded to pass into circulation) was demonstrated in some studies (leaky gut is discussed in more detail here). Others found evidence of low activity of intestinal carbohy­drate digestive enzymes. (6) The results of these different studies taken together sug­gest that significant digestive tract pathophysiology may accompany autism, at least within a subpopulation of patients. (4)

However, other studies have refuted these claims. The authors of a UK study published in 2002 concluded that there was not a substantial association between gastrointestinal illness in children and the development of autism. (7) Nevertheless, the authors acknowledged that some children may have had subclinical GI symptoms that were overlooked and that severe GI disease may be associated with autism in certain individuals.
Sensitivity to Cow’s Milk and Gluten in Autism

The frequent reports from parents that cow’s milk and wheat seemed to increase their child’s autistic symptoms prompted several studies on the possibility that com­ponents of these foods could be involved in triggering or exacerbating autistic symp­toms in some children.

Two separate studies involving a large number of autistic patients reported that an improvement of social, cognitive, and communication skills occurred when they were placed on a diet free of gluten and cow’s milk or a diet free of cow’s milk alone. (8,9)

A 2010 study of 72 children (ages 4 years to 10 years, 11 months) diagnosed with autism spectrum disorder (ASD) indicated that a gluten- and casein-free diet improved the test parameters of the treatment group compared with the placebo control group. (10)

The Possible Roles of Gluten and Casein in Autism

Two types of proteins have been reported to be involved in triggering or exacerbat­ing certain types of autism, namely casein (in milk) and the gliadin fraction of gluten in wheat. Digestion of dietary casein and gluten in the small intestine by the action of pancreatic and intestinal peptidase enzymes leads to the production of short chain peptides, which are structurally similar to endorphins. (Endorphins are neuropeptides that bind to opioid receptors in the brain and affect pain perception.)

These products are called exorphins to reflect their dietary origin. Gliadomorphins are a family of exorphins released from the partial digestion of the wheat protein gliadin. Similarly, casomor­phins are a family of exorphins released upon partial digestion of the milk protein casein. Casomorphins and gliadomorphins have been shown to affect the brain in experimental animals and may be psychosis-inducing agents. (4)

The Hyperpermeable Digestive tract (Leaky Gut) in Autism

In some autistic children the opioid peptides from the diet move through the lining of the digestive tract into blood and are carried to the brain as the blood circulates through the various organs in the body. This was found when it was discovered that the epithelium lining the digestive tract in some autistic children was more permeable than normal. (11) Thus, the “leaky gut hypothesis” was proposed (see here for more on the leaky gut). (4,12,13)

It was suggested that because of the increased permeability, larger mol­ecules than normal are able to pass through the lining of the digestive tract into cir­culation. Digestion products of natural foods such as casein and gluten-containing grains may thus be able to elicit immunological responses and interfere directly with the central nervous system.

A 2010 study (13) demonstrated that a significantly greater percentage of patients with autism and their close relatives had considerably higher scores on the intesti­nal permeability test (IPT)—36.7% and 21.2%, respectively—than the nonautistic population (4.8%). (Details of the lactulose/mannitol permeability test used in de­termining intestinal permeability are provided beloa.) The authors suggest that the increased IPT levels found in first-degree relatives indicates the possibility of an intestinal (tight-junction linked) hereditary factor in the families of subjects with autism. The study further reported a significant decrease in the IPT scores in autistic persons following a gluten- and casein-free diet.

There is a lack of evidence to suggest that casein, gluten, or their products cause the leaky gut. However, some researchers equate the process to celiac disease (14) in which immunological reactions to the gliadin fraction of gluten damage the intesti­nal villi that line the digestive tract epithelium and may result in hyperpermeability. Other studies (15) suggest that the improvement of autistic children on a gluten-free diet indicates that malabsorption of essential nutrients in celiac disease predisposes to symptoms of autism.

According to the proponents of the theory that vitamin B-12 deficiency may play a role in certain types of autism, pathology in the lining of the ileal region of the small intestine in autistic children, which has been observed in a few studies, could interfere with vitamin B-12 being transported into circulation. (16)

If absorption is severely inhibited, the resulting lower blood vitamin B-12 could interfere with the formation of myelin, the lipoprotein material surrounding the axon of certain nerve fibers. Myelin is necessary for normal conduction of the nerve impulse (action po­tential) in myelinated nerve fibers. Therefore, impairment in nerve conduction could result in the neurological deficits observed in autism. However, direct evidence of vitamin B-12 deficiency and impaired myelin formation in autism is lacking at this time.

A 2010 study (17) of 3- to 8-year-old autistic children indicated that vitamin B-12 supplementation improved autistic symptoms in 9 (30%) of their subjects, suggest­ing that a subset of children with autism disorder may benefit from B-12 supple­mentation. In general, authorities suggest regular monitoring of the B-12 levels in the blood of autistic children and supplementation, usually by injection, if the levels are found to be abnormally low. Ensuring that the diet includes adequate levels of vitamin B-12 is an obvious measure for ensuring optimal nutrition in any child, but especially autistic children whose diet may be rather unbalanced because of their own food preferences.

Magnesium, Vitamin B-6, and Autism

In the 1950s, megavitamin therapy became popular as a treatment of several chronic conditions. Autism was one of the conditions in which it was hoped that extremely large doses of vitamins might improve a child’s mental processes. Vitamin B-6 (py­roxidine) was discovered to improve speech and language in some children with “autism syndrome.” However, vitamin B-6 in high doses can be toxic, with several adverse effects, which were considerably reduced when magnesium was given at the same time.

Since 1980, numerous published studies have attempted to assess the effects of vitamin B-6 and magnesium on a variety of characteristics such as verbal com­munication, nonverbal communication, interpersonal skills, and physiological func­tion in individuals with autism. (18) These studies were subject to scientific evaluation and review (19) in 2003. The authors concluded that due to insufficient evidence, they could provide no recommendations on the use of vitamin B-6 with magnesium as a treatment for autism.

Some clinicians have been investigating the possibility that magnesium alone as a supplement may improve symptoms in autism. This was based on the observation that children with autistic spectrum disorders had significantly lower plasma con­centrations of magnesium than normal subjects. (20) Because magnesium is an essential element in several important physiological processes, it has been suggested that a de­ficiency might lead to impairment in certain brain functions that could contribute to the autistic disorder. However, studies on magnesium and its role in autism have not yet defined the deficiency or determined whether supplementation with the mineral is effective in treatment.

Dietary Preferences and the Restricted Diet

Children with autism tend to have strong preferences in their food selection. Many have intense dislikes for some foods, while they crave others and tend to select them repeatedly. They also tend to have very definite ideas about form and texture. For example, the author of this book had one client who would eat food only in the form of patties, but this was ideal because a wide range of chopped up foods could be incorporated into his patties, which in the uncut state he would reject outright. Con­sequently, the client was provided with a well-balanced diet, in spite of his limited food preferences, using fish-, meat-, or poultry-based patties containing a variety of chopped vegetables and fruit. However, in many cases, this selectivity means that an autistic child’s diet is already limited, and parents and health care providers may be reluctant to restrict the child’s food intake any further. Consequently, a gluten- and casein-restricted diet is not an attractive option for many.

Summary: Can Dietary Interventions Prevent or Treat Autism?

Many reports from parents and research studies have indicated that a variety of dietary interventions may have success in ameliorating symptoms in certain children with autism. (21) The most studied and successful have been discussed here.

Currently, experts do not agree on whether dietary manipulation can help pre­vent autism or aid in its treatment. Researchers in the field tend to agree that dietary manipulation is recommended if the child’s behavior improves on the restrictions or supplements. However, many practitioners hold the opinion that “the link between autism and a gastrointestinal pathophysiology is not substantiated by research. The dietary approaches employed are cumbersome, not proven to be efficacious, and may further narrow the food choices of the child with autism.” (22)

If any dietary manipulation provides some improvement, parents, caregivers, and clinicians are usually open to a trial on the suggested diet. If a parent feels there is a chance that their child might benefit from a gluten- and casein-restricted diet, it may be worthwhile to try the diet—for a limited time only. If the child’s behaviour does not noticeably improve after strictly adhering to the guidelines for a month, then the restrictions should be abandoned because it is unlikely that they are pro­viding any benefit. As with any dietary manipulation, it is essential that any foods removed from the diet be replaced with those of equivalent nutritional value.

No evidence suggests that very high doses of any single nutrient are beneficial. In fact, the contrary is usually true. Excessive quantities of many vitamins and min­erals can be toxic, and frequently, excess of one leads to deficiency in another, as they compete for absorption and metabolites. Each nutrient plays an essential role in keeping the body healthy; refer to the Dietary Reference Intakes (DRIs) published by the Institute of Medicine for recommendations about the levels of various nutri­ents that are ideal at each developmental stage. (23)

The Tolerable Upper Limits set in the DRIs should not be exceeded except in specific medical conditions, which will be decided by a medical specialist in individual cases. Further studies are needed to establish the efficacy of any dietary intervention in the management of autism, to identify those individuals who would most benefit, and to determine the mechanism responsible for triggering any adverse responses.
 
References

1. Kaneshiro NK, Zieve D. Autism. PubMed Health U.S. National Library of Medicine. National Institutes of Health. April 26, 2010. Accessed May 4, 2012.
2. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR). Washington, DC: American Psychiatric Association; 2000.
3. Tuchman RF, Rapin I. Regression in pervasive developmental disorders: seizures and epileptiform electroencephalogram correlates. Pediatrics. 1997;4:560–566.
4. White JF. Intestinal pathophysiology in autism. Exp Biol Med. 2003;228:639–649.
5. Lightdale JR, Siegel B, Heyman MB. Gastrointestinal symptoms in autistic children. Clin Perspect Gastroenterol. 2001;1:56–58.
6. Horvath K, Papadimitriou JC, Rabsztyn A, Drachenberg C, Tildon JT. Gastrointestinal abnormalities in children with autistic disorder. J Pediatr. 1999;135:559–563.
7. Black C, Kaye JA, Jick H. Relation of childhood gastrointestinal disorders to autism: nested case-control study using data from the UK General Practice Research Database. Br Med J. 2002;325:419–421.
8. Lucarelli S, Frediani T, Zingoni AM, et al. Food allergy and infantile autism. Panminerva Med. 1995;37:137–141.
9. Knivsberg A, Reichelt KL, Nodland N, Hoien T. Autistic syndromes and diet: a follow-up study. Scand J Educ Res. 1995;39:223–236.
10. Whiteley P, Haracopos D, Knivsberg AM, et al. The ScanBrit randomized, single-blind study of a gluten- and casein-free dietary intervention for children with autism spectrum disorders. Nutr Neurosci. 2010;13(2):87–100.
11. Liu Z, Li N, Neu J. Tight junctions, leaky intestines, and pediatric diseases. Acta Paedi­atr. 2005;94(4):386–393.
12. Uil JJ, van Elburg RM, van Overbeek FM, Mulder CJ, VanBerge-Henegouwen GP, Hey­mans HS. Clinical implications of the sugar absorption test: intestinal permeability test to assess mucosal barrier function. Scand J Gastroenterol Suppl. 1997;223:70–78.
13. de Magistris L, Familiari V, Pascotto A, et al. Alterations of the intestinal barrier in pa­tients with autism spectrum disorders and in their first-degree relatives. J Pediatr Gastro­enterol Nutr. 2010;51(4):418–424.
14. Barcia G, Posar A, Santucci M, Parmeggiani A. Autism and coeliac disease. Autism Dev Disord. 2008;38(2):407–408.
15. Genuis SJ, Bouchard TPJ. Celiac disease presenting as autism. Child Neurol. 2010;25(1):114–119.
16. Wakefield AJ, Murch SH, Anthony A, et al. Ileal-lymphoid-nodular hyperplasia, non-spe­cific colitis, and pervasive developmental disorder in children. Lancet. 1998;35:637–641.
17. Bertoglio K, Jill James S, Deprey L, Brule N, Hendren RL. Pilot study of the effect of methyl B12 treatment on behavioral and biomarker measures in children with autism. J Altern Complement Med. 2010;16(5):555–560.
18. Mousain-Bosc M, Roche M, Polge A, Pradal-Prat D, Rapin J, Bali JP. Improvement of neurobehavioral disorders in children supplemented with magnesium-vitamin B6. II. Pervasive developmental disorder-autism. Magnes Res. 2006;19(1):53–62.
19. Nye C, Brice A. Combined vitamin B6-magnesium treatment in autism spectrum disorder. Cochrane Database Syst Rev. 2002;(4):CD003497. Review.
20. Strambi M, Longini M, Hayek J, et al. Magnesium profile in autism. Biol Trace Elem Res. 2006;109(2):97–104.
21. Srinivasan P. A review of dietary interventions in autism. Ann Clin Psychiatry. 2009;21(4):237–247.
22. Johnson TW. Dietary considerations in autism: identifying a reasonable approach. Top Clin Nutr. 2006;21(3):212–225.
23. Institute of Medicine. Dietary Reference Intake Tables and Application. Accessed May 4, 2012.

Additional Resources

For client education on a gluten- and casein-free diet and other topics related to food allergies and intolerances, look for Food Allergies and Intolerances: Client Education Tools for Dietary Management in the Academy of Nutrition and Dietetics on­line store.

You can buy all of Dr Joneja's books here or here in the US.

First Published in 2014

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