Autism is correlated with gastrointestinal symptoms, such as constipation, regurgitation, chronic diarrhea, distention, and excessive acid reflux. Nutritional deficiencies (due to selective eating and sensory issues that are hallmarks of the condition), food intolerances, and food allergies are also common. As a result, nearly 20% of autistic children are placed on a special diet by their parents.
Unsurprisingly, during the rise in popularity of the gluten-free diet, anecdotal evidence for a diet lacking gluten (a protein compound that forms during the making of dough) and casein (a protein found in cow’s milk) began to circulate in blogs and publications aimed at parents of autistic children. The gluten-free/casein-free diet (often abbreviated as GFCF) originates from the opioid excess theory, proposed by a neuroscientist in the 1970s and popularized in the 1990s. This theory hypothesized that diets high in gluten and casein led to excessive opiate-like peptides traveling via the gastrointestinal system and bloodstream to the brain. These researchers reported that urine samples from autistic participants had higher levels of these peptides, which they assumed to cause emotional distress and autism.
This idea was reinforced by the notorious 1998 Andrew Wakefield experiment, which suggested that the measles, mumps, and rubella (MMR) vaccine caused gastrointestinal distress and autism. The study gained traction in the news and heavily influenced public perception of autism, until other researchers found contradictory results and evidence that the data had been falsified began to mount. Wakefield’s medical license was revoked after it was also discovered that he stood to profit from an alternative to the MMR vaccine, failed to gain ethical approval from an institutional review board, completed unnecessary invasive procedures (including colonoscopies and painful lumbar punctures) on child participants. Since these studies, the body of research on this topic has repeatedly found no significant increase in the number of opioid peptides in the urine of autistic children or adults.
Despite this, the gluten-free and casein-free diet continues
to be popular in the autism-inclusive community. The diet is easily accessible,
and many outlets with less stringent standards for scientific validity promote
it via parent testimonials, cookbooks, and articles. Some parents may start the
diet, and begin to perceive changes in their child’s demeanor or behavior due
to the placebo effect. The diet can genuinely help a small number of children
who have genuine casein allergies or gluten intolerances, which are slightly
more prevalent in autistic people than the general population.
If parents still wish to try this diet, experts in
gastrointestinal distress and nutrition in autistic children recommend:
Trying an elimination
diet only under the supervision of a physician or registered dietitian.*
Gluten-free and casein-free diets can cause several nutritional deficiencies
and issues, and having a professional monitor your child’s health can mitigate
that risk. Parents doing this should eliminate any foods containing gluten or
casein from their child’s diet for a month, while keeping daily documentation
of bowel movements and any signs of gastrointestinal upset. Recording symptoms
is the best way to objectively compare symptoms, communicate with clinicians,
and reduce biases that may cause the diet to seem more effective. After a
month, slowly introduce a new food every few days and continue to log symptoms.
* Consult a registered dietitian, rather than a nutritionist. Registered
dietitians have strict licensure and education requirements, while
nutritionists have none.
Providing supplements of vitamins and minerals commonly missed in a gluten-free/casein-free diet.
Fiber, protein, and omega-3 fatty acid levels are often lower than recommended by the FDA in autistic children following the CFGF diet. Lean proteins, such as chicken, legumes, and fish, can assist in building protein and fatty acids if tolerated by the child. Popcorn, fruit, and whole-food carbs (such as potatoes) provide fiber and are well-tolerated by many autistic children. Children’s multivitamins and fish oil supplements can also reduce deficiencies, but parents should check for the US Pharmacopeial Convention (USP)’s seal on packaging. The USP verifies the ingredients and dosage of over-the-counter supplements. Fraudulent ingredient listings, toxic additives, and inaccurate dosage claims are common in the industry.
Limiting the amount
of rice-based ingredients and foods to avoid accumulation of heavy metals.
Rice is a staple in gluten-free diets, but can accumulate arsenic and mercury
from the soil, fertilizer, and water during its growth. Recent research has
shown that people who follow a gluten-free diet have higher levels of mercury
(70% higher on average) and arsenic (200% higher on average) compared to the
general population. More research is needed before assuming a causal link
between rice consumption and heavy metal accumulation in gluten-free diets, but
dietary experts recommend choosing whole foods and other gluten-free grains
(such as quinoa, millet, oats, and corn) and relying less on rice-based grains
and flours to prevent neurological issues that accompany long-term arsenic and
Choosing, non-processed foods, communicating often with
treatment team members, and monitoring for sudden changes in mood, energy
levels, and digestive issues are the safest, best way to initiate any change in
your child’s diet, especially when incorporating major changes such as the
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