Food Matters

The Science on Autism and Gastrointestinal Issues

There are two distinct avenues for supporting those with autism: therapeutic interventions (behavioral therapy, speech therapy and sensory integration) and physical interventions (medical treatment, dietary intervention and nutrient supplementation). Less familiar are the physical interventions, despite the fact that many therapists and parents have noticed that improved overall health leads to greater effectiveness of therapeutic interventions. In addition to the common social and behavioral symptoms, children with autism routinely suffer from physical ailments, including gastrointestinal issues, immune system weakness, food allergies and aversions and increased inflammatory response. Their impaired bodily systems and compromised underlying biochemistry affect their health, learning ability, and autism symptoms. According to a 2001 Nutritional Neuroscience report on dietary intervention in autistic disorders, certain food substances (notably gluten and casein) are known to be problematic for children with autism and should be avoided, and foods rich in healing nutrients are beneficial when added to children’s diets. Attention to these factors is intended to help balance biochemistry, affect systemic healing, and provide relief of autism symptoms. These are the underlying tenets of all “autism diets.”

When you add a specialized diet, supplementation and nutrition to your autism treatment plan, you may open the door to better sleep and cognitive ability, less pain and rashes, improved digestion and positive changes to varied autism behaviors and symptoms like eye contact, language, reduced hyperactivity and greater attention span. But before embracing this strategy, it’s important to understand the science of how diet and nutrition may help.

Autism affects the whole body

Autism has historically been considered a “mysterious” psychological disorder, the origin and impact of which was solely on the brain. But through the breakthrough work of the Autism Research Institute, a more appropriate “whole body disorder” (i.e. the brain is affected by the biochemistry generated in the body) perspective of autism has emerged.

Understanding that children with autism may suffer from physical symptoms—diarrhea, constipation, bloating and gastrointestinal pain, infections, sleeping challenges and inflammation or pain—as well as behavioral symptoms demonstrates that autism is not a psychological disorder, and you can begin to comprehend how the systems of the body and its cells affect the brain and how food choices can influence biochemistry and children’s behavior.

Food matters for children with Autistic disorders

A healthy diet is essential for good health, and good digestion is critical. A 1999 Journal of Pediatrics article on gastrointestinal abnormalities in children with autistic disorders concluded that “unrecognized gastrointestinal disorders … may contribute to the behavioral problems of the nonverbal autistic patients.”

In children with autism, poor digestion often stems from environmental factors (as well as genetic susceptibility), lack of beneficial bacteria, inflammation and immune system response to certain foods. Studies have also shown that leaky gut—a result of damage to the intestinal lining making it less capable of absorbing nutrients and filtering bacteria, toxins and foods that are not entirely digested—low levels of beneficial flora (bacteria that aids digestion), inflammation and immune response to food may also be a culprit to poor digestion. Additionally, the response to certain foods such as gluten and casein can create an opiate or inflammatory reaction that can affect the brain.

Referring to the chart below, Whole Body Disorder, note the complex set of factors that influence autism on the left side: toxins, environmental factors, digestive health and inflammation. The right side shows the direct effects these factors can have on the brain. The gut is a significant component to what happens in the brain.

The gut is an essential component to understanding and addressing autism. The gut digests the food we eat and extracts the nutrients needed to support biochemistry and proper brain function. The largest part of the immune system is found in the gut—which is often imbalanced in those with autism, affecting a child’s ability to fight viruses yeast, and other pathogens properly while contributing an overactive inflammatory and allergic response. Toxins in the gut (often from bad bacteria and yeast) can affect the brain. Foods that are not digested properly can create inflammatory and immune system responses affecting the brain. Approximately 90 percent of the brain chemical serotonin is found in the gut.

It was Michael Gershon, MD, chairman of the department of anatomy and cell biology at Columbia, who referred to the gut as “the second brain” in his 1999 book of the same name, which points to the strong relationship between the human brain and the gut. And understanding that the gut and brain are connected helps to explain why autism symptoms and overall health are improved through a diet that supports digestion and gastrointestinal health.

The gluten-free, casein-free diet for Autistic children

When parents choose to follow an autism diet, they typically begin with a gluten-free, casein-free diet. There are many good books about this diet (see p. 19), and the food marketplace is increasingly gluten-free, casein-free friendly (see p. 32).

When ingested by those with a compromised digestive tract, which is common in children with autism, gluten and casein proteins can cause gut inflammation, pain and digestive problems. If the protein is not properly broken down during digestion, it can form opioids (opiate or morphine-like compounds). Scientists believe, as reported in a 2002 study published in Expert Opinion on Therapeutic Topics, that opioids in gluten and casein are toxic for children with autism due to the fact that these children have an abnormal, leaky, gastrointestinal tract. The properties of gluten and casein can lead to digestive problems such as diarrhea, constipation, gas, bloating, as well as foggy thinking and inattentiveness for many children with autism.

According to parents surveyed by the Autism Research Institute in a 2005 study, a gluten- and casein-free diet is helpful for 65 percent of children with autism, even though a food sensitivity panel may or may not have shown a reaction to these foods. Other parent surveys exceed 80 percent effectiveness.

For those wishing to start their child on a gluten- and casein-free diet, it’s more than just avoiding bakery items made with wheat and other gluten grains and dairy foods such as milk, cheese, butter, yogurt and cream. Be sure to carefully read all ingredient labels, and talk to your healthcare professional before starting (see “Getting the Green Light” on p. 16 for tips on talking to your healthcare professional).

How imbalanced digestion and biochemistry affect the brain and autism symptoms

When there is yeast overgrowth in the gastrointestinal tract, toxins enter the bloodstream and make their way to the brain where they can cause symptoms ranging from foggy thinking to drunken behavior, according to a 2000 report published in Medicine, Science and the Law.

When the biochemistry of methylation is not working properly, neurotransmitters cannot function properly, therefore increasing the likelihood of anxiety, depression, ADHD and sleeping issues, as reported in a 2008 issue of Alternative Medicine Review.

Toxins, food sensitivities, bad bacteria or yeast in the gut can cause inflammation in the gut and brain. This can, as noted in the November 1999 Journal of Pediatrics, cause pain that affects behavior, particularly self-injurious behavior (e.g. leaning over furniture, eye poking and head banging can all be signs of pain).

When detoxification is poor, as is common with autism, toxins from food and the environment can build up and act like drugs on the brain, causing irritability, aggression and brain and cellular damage, as with salicylates, artificial ingredients, MSG, mercury and aluminum, according to a 1997 report published in Brain Dysfunction and a 2008 report published in Hearing Research.

When digestion is poor and the gut is too permeable (i.e. leaky gut), the nutrients cannot be absorbed properly. This leads to nutrient deficiencies, which can affect all cellular functions including poor brain function.

Opiates can be created from inadequate breakdown of gluten, casein and soy leading to symptoms of opiate excess—foggy thinking, insensitivity to pain, opiate addiction and withdrawal and irritability.

Removing the offending foods that contribute to inflammation, trigger immune response (food sensitivities), create opiates and increase toxicity is crucial. And adding foods that can support a healthy ecosystem and provide needed nutrients is essential.


Candace McDonald, executive director of Generation Rescue, a leading organization dedicated to helping families get the resources they need to heal and recover their children with autism spectrum disorders, sits down with Julie Matthews, CNC, to discuss starting dietary interventions later in life, possible infractions, and dealing with the challenges of dietary restrictions in day-to-day life.

Q & A:

Candace McDonald: Julie, thank you for sharing this critical information on the science of the diet with parents. We at Generation Rescue are strong proponents of autism diets, particularly the gluten-free, casein-free diet in conjunction with traditional therapeutic interventions. Not only did Jenny McCarthy see great results with her son, Evan, but our grant program requires families to pursue an autism diet as part of the treatment.

Something that has been on my mind and the minds of many in the community is the amount of children who will become teens and adults with autism in the next 10 years. I know first hand that there are unique circumstances and challenges facing this group. I’d love to ask you some questions specific to them.

Is it too late to start following a gluten-free, casein-free diet as an adult with ASD to see benefits? Is the damage from not following a gluten-free, casein-free diet too far gone to have an effect when starting so late in life?

Julie Matthews: It’s never too late—improvements can be made at any age.

If you found out at 90 years old that you had celiac disease, you’d still get great benefit from taking wheat out of your diet. Now, while some of the damage may be further along and not correctible, improvement, and often significant, will still result.

Because of the biochemistry routinely seen in autism, inflammation is common. This inflammation continues on and on for years, never turning off as it should, and can damage the brain. Some of this damage appears permanent, partly evidenced by not seeing full recovery in adults very often. But that doesn’t mean dietary intervention is not helpful. In fact, it is often extremely helpful—elimination of diarrhea, constipation or other digestive disturbances, less hyperactivity and better focus, and even improvements in language are possible in teens and adults.

Food is one of the biochemical factors that contribute to inflammation. Foods like gluten and casein can create inflammation, and in their case opiates as well. Sugar contributes to inflammation. When we see it’s sort of the biochemistry that needs “fixing,” we can see that diet plays an important role in stopping that inflammatory process and not contributing more.

While improvements may not be as great as with a three year old, there are almost always improvements in one way or another, and improving diet is always worth a try. There is no downside to improving diet for anyone at any age.

CM: How long should an adult with ASD be on the gluten-free, casein-free diet? Does it need to be a lifetime change?

JM: The time for healing varies. For some, it can be a year or so. For others, when gluten or another food is overtly harmful, they may avoid it for life. Wouldn’t you? To be fair to yourself and your healing body, I suggest adults give it a six-month trial at minimum. If you are not seeing desired results, you may consider other dietary and health/medical strategies before going off the diet.

CM: What steps would you suggest for an adult starting the gluten-free, casein-free diet?

JM: The steps for an adult are similar to a child going gluten free and dairy free. Begin by finding suitable substitutes for you favorite gluten- and casein-containing foods. For example, if you like toast in the morning or a sandwich at lunch, start by finding tasty gluten-free bread. If you enjoy pasta, choose a rice pasta or other substitute. If you want a dairy-like treat, try coconut milk ice cream. However, remember to make it healthy—a little bread or pasta or treat is fine from time to time, but too much (gluten free, casein free or not) is not good for anyone.

CM: Can you suggest options for social functions for a teen or adult and the gluten-free, casein-free diet?

JM: There are many. It depends if you are creating the event or are part of the fun. One of the best things for all social functions is to strategize ahead of time on what your food options will be. Check to see if where you are going has gluten-free, casein-free options. Bring some safe snacks in case there are no good food options.

You might consider eating something before you go, so you don’t have to be hungry or be tempted to go off the diet if they don’t have anything within your needs.

Choose an activity that is not centered around food, such as bowling, or a gathering at the zoo, aquarium, museum, sporting event. Sometimes bowling alleys, zoos and sporting events have healthy food vendors, too—so you could check into that ahead of time. If not, then bring your own.

If you are planning the party, go somewhere where you can bring the food you want, rather than that being in the hands of the restaurant. Picnics, trips to the park or beach outings are always “bring your own” so you can plan ahead and have the good food you need.

CM: How can inflammation caused by gluten and casein have an effect on an adult?

JM: There are many types of symptoms you can get from gluten and casein. The inflammatory reaction from these foods often creates pain and digestive symptom even neurological and mood conditions, like headaches or migraines, gas, bloating, diarrhea or constipation and joint pain. Even depression has roots in inflammation.

The good news about this is that removing problematic food can often have a dramatic effect on how you feel because improvements touch on many areas from pain to energy to mood.

CM: Please share with us some tips on how to deal with infractions.

JM: Infractions are part of life—sometimes accidental, at other times intentional. Either way, it’s good to have some tips to help. Digestive enzymes with DPP-IV (a dietary supplement) can help break down the proteins and opioids from gluten, casein and soy. It’s good to have some on hand in case you are not 100 percent certain about restaurant food or if you eat some with gluten or dairy.

Some people try digestive enzymes instead of a gluten- and casein-free diet. However, I don’t think it’s a replacement for the special diet because there are many reasons for food reactions not all are addressed by

GR: And how does good nutrition help deal with these issues during puberty?

JM: Good nutrition is important to maintain during puberty because a lot of growth occurs during this time, and you want to make sure you have the building blocks (protein, energy, nutrients) needed to grow and develop. Also, certain foods like soy contain estrogen and may negatively impact hormonal changes for both boys and girls. Soy is actually broken down by the same enzyme as gluten and casein, so I recommend avoiding soy for several reasons. Plastics in food storage, pesticides in produce and hormones fed to animals can mimic estrogen—important chemicals to avoid for anyone, but particularly if you are going through hormone changes and developing based on the right balance of hormones. Eating healthy, wholesome food is important during puberty—meat, vegetables, gluten-free whole grains, fruit and other nutritious foods.

CM: Where is a good place to start with teens who are skeptical and do not want to follow a special diet?

JM: On one hand the autonomy and awareness teens have makes changing a diet especially challenging. On the other hand, a teen also has more ability to reason and make choices for themselves. As a parent, you may be able to gain leverage and get their opinions—no teen wants smelly gas, a bloated belly or behaviors that call negative attention to them. You may be able to help them see their ‘pain’ points, ways the diet may help them, and they might be willing to try it for a period. Make the timeframe short and manageable with a good reward—not food-based—at the end. The only point to be careful with is if the timeframe is too short, you might not have time to see the benefits.

Another great place to start if you can’t convince your teen to give up pizza is to start with artificial additives. Start by engaging them with some research into the reactions you can get from artificial colors, flavors, preservatives and MSG. They can have a dramatic effect on hyperactivity, inattentiveness, aggression, irritability and learning. Read labels and get them curious about what is in their food. Then avoid the sodas, candy, chips and junk food with these artificial ingredients. See if they notice a difference. If so, that can lead into a discussion about the power of food and the possibility of trying a gluten-free, casein-free diet.