Did you know that people with autism are more likely to suffer from gastrointestinal (GI) problems[1]?. 

While it’s still unclear whether GI problems cause autism, or whether people with autism are simply more likely to have GI problems (without a known cause), one prominent theory is called leaky gut syndrome. Leaky gut leads to absorption of incompletely digested proteins causing an overstimulation of the immune system in the bloodstream [1]. Resulting in inflammation of the gut lining of the intestine and  increased permeability, making it easier for elements to pass through into the blood stream and travel to the brain and tissues[2].

Examples of proteins that can be incompletely digested include:

·       Gluten: Such as cereals, wheat and barley

·      Casein: Found in milk and dairy products

As not all the protein from these substances is broken down, some parts remain and cause uncomfortable gut symptoms. Gut symptoms can include abdominal pain, gas, bloating, chronic constipation, chronic diarrhoea and loose stools [ 2] . In addition, this process of poorly digested proteins can have a similar effect to opioid drugs, leading to a range of issues including repetitive behaviours, lack of concentration, and a worsening of GI problems and other typical autism symptoms.

Although there’s not currently enough research to fully explain the relationship between these foods and the resulting symptoms, a number of studies have found that switching to a gluten-free/casein free diet (GFCF) can significantly improve behaviour, development and health in people with autism[3]. However, following a gluten-casein elimination diet can lead to nutrient deficiencies and is not recommended as a general treatment for ASD. For those who wish to trial this diet will need to be closely monitored by a dietitian [3 & 4].

What is Gluten Intolerance?

Gluten is a protein found in foods such as wheat, barley, rye and oats.

Symptoms of gluten intolerance can include gut disturbances, such as:

·       Bloating

·       Flatulence (excessive wind)

·       Diarrhoea or constipation

·       Stomach cramps

·       Nausea and vomiting

·       Abdominal pain

In turn, these uncomfortable gut symptoms can lead to other problems, including:

·       Fatigue

·       Weakness

·       Anaemia

·       Weight loss

·       Problems with bowel movements

·       Irritability

·       Smelly stools

·       Delayed growth or puberty


How Can You Manage Gluten Intolerance?

For people who are very sensitive to gluten, even tiny crumbs of gluten can cause stomach upsets. The only way to completely avoid all the symptoms of gluten intolerance is to follow a strict gluten-free diet. This will enable the gut and the lining of the intestine to heal and return to normal.

Before switching to a gluten-free diet, it’s important to seek medical advice to determine the cause of your symptoms. In many cases, these symptoms may not be caused by gluten specifically.  Some GI problems can be a result of a decreased level of certain digestive enzymes such as disaccharidases, gluccomylase, lactase and sucrose, thus predisposing to disorders associated with starch metabolism, carbohydrate malabsorption and intestinal disorders [2]. It may then be beneficial to follow a low FODMAP diet to identify if GI symptoms are resulting from irritable bowel syndrome.

Therefore it is essential that before cutting out gluten from your diet that you are properly diagnosed as it may be unhealthy for you to follow a gluten free diet. Please be sure to seek medical advice or speak to a specialist dietitian. The good news is, a simple blood test or allergen test can assist with diagnosis of coeliac disease.

Dietitian Services for Gluten Intolerance

When commencing a gluten-free diet, a dietitian can help you meet your goals by designing a food plan, and ensuring you are aware of which foods contain gluten and what you can substitute these with. You might be surprised at just how many ‘everyday’ foods contain gluten!

A dietitian will also help you track and monitor your symptoms, in order to evaluate the results of your dietary changes.

What is a casein free diet?

Casein is the main protein found in cow’s milk, cheese, yoghurt and ice cream.  There are two major genetic variants of beta-casein A1 and A2. A1 beta-casein has been found to release the opioid peptide upon digestion “increasing the opioid drug like effect” where A2 beta-casein does not or if it does it does at a much lower rate. Some research has shown that once casein is eliminated from the diet improved behaviour soon follows [5] .

Symptoms of casein intolerance can include:

·      Gut inflammation

·      Abdominal pain

·      Bloating

·      Behavioural issues

Dietitian Services For casein free diet

When switching to a casein-free diet, it’s important to work with a dietitian who can help you understand what steps you need to take. A dietitian can also help with designing a meal plan and guidelines to ensure you’re still getting enough calcium for healthy bones and teeth, which is particularly important for children.

Plus, a dietician will help you track and monitor your symptoms, in order to evaluate the results of your dietary changes.

Are you concerned about gut and behavioural problems in someone with autism? Our dietitians can help you find out whether these are caused by a gluten or lactose intolerance, and assist you in taking the next steps to achieve your goals. Learn more about our dietitian services, which are supported by your NDIS funding. 


For people who are lactose intolerant, the milk sugars are only partially digested in the small intestine. The lactose that’s left behind is broken down and fermented by bacteria in the intestine, leading to symptoms of lactose intolerance, including:

·       Bloating

·       Flatulence (excessive wind)

·       Diarrhoea

·       Stomach cramps

·       Abdominal pain

·       Smelly stools

How Can You Manage lactose Intolerance?

If you are diagnosed as lactose intolerant, changing to a lactose-free or low-lactose diet can help to avoid the symptoms of your condition.

While most dairy products contain lactose, some have lower levels of lactose than others. The following dairy foods all contain lactose:

·       Milk, milk solids and milk powder

·       Cow and goat's milk

·       Whey protein

·       Most flavoured milks and smoothies

·       Milk-based ice-creams

·       Cheesecake

·       Cheese

·       Yoghurt

·       Cream


Want to chat with us about your health concerns and our services to help? Call us on 1300 448 100 or fill in the form below and we can get back to you.