Picky Eating and Autism

“Picky” or restricted eating is extremely common in autism.  The roots of this symptom lie in different areas and comprehensive assessment is often needed to identify each child’s individual underlying contributors.  Environmental toxins like lead, mercury, aluminum, pesticides, bisphenol A and other plastics, fire retardants, phthalates etc. deplete nutrients required to support appetite.

Zinc deficiency

Zinc is involved in 200 enzymatic functions in the body including detoxification of harmful substances via the metallothionein complexes produced by the methylation cycle.  One of the most important of nutrients related  healthy appetite is zinc which is often deficient in patients with chronic illness. Zinc deficiency in pregnancy has been linked to increased risk of autism.  Children diagnosed with autism have higher levels of heavy metals and environmental pollutants contributing to lower level of zinc levels.  Alteration in the IDO pathway due to chronic, low level infection with harmful microbes (clostridia, yeast, lyme, viruses) and stimulation of the cell danger response will deplete zinc very quickly.

Serotonin regulation

Ninety percent of serotonin is made in the gut.  Serotonin is needed to regulate appetite and plays a role in small intestinal motility (the muscular movement required to move through the small intestine where the majority of nutrients are absorbed).  Serotonin is produced with the help of B vitamins, vitamin C, folic acid, selenium, calcium, magnesium and the amino acid tryptophan.  Methylation includes a “folate cycle” which recycles biopterin to produce and regulate serotonin.  Alterations in the IDO pathway will cause dysregulation of serotonin negatively impacting diet and creating carbohydrate craving.

Stress, hormones and neurotransmitters (brain chemicals)

People diagnosed with autism experience high levels of stress for a variety of reasons.  Their bodies tend to persist in a “freeze, fight or flee” mode generally called “fight or flight”.  This system has to have proper regulation.  Too much stress (sympathetic) or relaxation (parasympathetic) slows down relaxation.  Sympathetic and parasympathic activity combined provide balance.  The vagus nerve is a cranial nerve that governs the parasympathetic (relaxation) aspect of the digestive tract.  Nerves are covered in a myelin sheath that is produced by the methylation cycle.  Impaired methylation impairs nerve transmission, decreasing the functionality of the downstream tissues and organs.  “Relaxataion” is an imperfect term in this role because the vagus nerve provides both excitatory and inhibitory control over gastric (stomach), intestinal (small and large intestine), and pancreatic functions (blood sugarcontrol and micro-digestion via enzymes).  The stomach and upper GI tract in have concentrated vagal innervation (control).  Innervation to the GI tract and pancreas is via a nerve that contains both sensory and motor fibres, the majority of which come from the vagus nerve.

Constipation, diarrhea, reflux

Digestive concerns create nutrient deficiencies that impact the stress response in addition to production and regulation of brain chemicals and hormones regulated by enzymes, antioxidants and genes.


The gut is home to hundreds of trillions of good bacteria.  These microbes help:

  • Support healthy sleep
  • Increase energy
  • Prevent infections
  • Decrease inflammation
  • Regulate mood
  • Support healthy immune function including improving immunity and decreasing autoimmunity
  • Make brain chemicals
  • Increase levels of vitamins and minerals
  • Improve essential fatty acid status
  • Regulate hormones and cholesterol levels
  • Detoxify harmful substances like lead and pesticides
  • Prevent and treat chronic diseases
  • Builds and maintains all cell membranes
  • Produce protective sheaths on nerves


Alterations in gut flora alter appetite and foodncravings in people with autism contributing to “picky” or restricted eating.  Low level infections trigger the cell danger response from the mitochondria increasing craving of sugar and carbohydrates.  This is also seen in depression when serotonin levels are low.  In a low serotonin system, carbohydrate cravings will be triggered to quickly elevated the level of serotonin.  Unfortunately, this is a very poor long term solution as it contributes to a biochemical cascade that sucks up 95% of the body’s tryptophan to manage.  This is akin to living off your credit cards; it becomes impossible to get ahead financially.  Microbiota (gut flora) can act on the vagus nerve, and also have access to the brain via a newly identified lymphatic system.  While research is still emerging, it is clear that the gut is the 2nd brain and plays a role in every aspect of health and disease.


One microbial family, streptococcus results in a type of restricted feeding that needs to be uniquely addressed.  Some children diagnosed with autism have an altered immune response to streptococcus, and potentially other microbes, resulting in an autoimmune response.  Avoidant/restrictive food intake disorder (ARFID) is commonly seen in children with PANDAS, PANS, PITANDS.


Dietary restriction creates a vicious cycle of “picky” eating because nutrients required to support the above biological processes are deficient.  Regardless of individual or combined underlying contributors (root cause) to feeding issues in children and adults with autism spectrum disorder, optimal diet is part of the solution.