Autism is a lifelong condition that affects the brain and how a person communicates and relates to other people and the world around them. It can make it difficult to make friends, tell people what you need and understand what other people think. Good nutrition is needed so that the brain can work properly. 

Severe autism has been linked to low levels of certain nutrients (vitamins B3, B6, C, calcium, iron and zinc). Good nutrition is important as poor diet can affect mood, learning and sleep. People with autism may have difficulty with sleeping. Healthy foods give the brain and body the nutrients that they need in the right amounts.

This Food Fact Sheet looks at the most common dietary problems affecting people with autism and how dietitians can help.

Some common problems are:

  • not liking mealtimes and only eating a few foods
  • constipation, diarrhoea and a bloated stomach
  • food hypersensitivity (when the body reacts badly to certain foods)

Problems with eating

Often people with autism have sensory issues which can change the way things smell taste and feel. This can make it difficult to eat certain foods. Eating less than 20 different foods is unhealthy, especially for children as it can restrict growth. In rare cases this eating behaviour can lead to very serious problems such as blindness, bone problems and vitamin deficiencies.

Some people with autism can become overweight if they eat too many sugary and fatty foods and not enough fruit, vegetables, fish or whole grains. This type of diet can make you feel unwell and increases your chance of having a heart attack or stroke.

Mealtimes are often full of lots of people, noises and smells and if you have autism this can be very stressful and make you unhappy about eating. If you are unhappy about food and eating or are overweight, then you could speak to a dietitian.

Dietitians can:

  • look at whether your diet is giving you all of the nutrients that you need
  • give advice to help you try new foods that you will like
  • give advice on nutritional supplements
  • give helpful, practical advice to help reduce mealtime stress

Problems with digestion

Digestion is when foods are broken down by the body into nutrients known as fats, proteins, starches, sugars, vitamins and minerals. Gut problems such as constipation, diarrhoea and a bloated stomach are quite common in people with autism and can affect your mood. Some people may find taking a probiotic helps to relieve gut problems.

Eating regular meals containing plenty of fibre and having 6-8 drinks every day will often help. High fibre foods include wholegrain breakfast cereals, wholemeal and granary bread, fruit, vegetables, salad, beans and lentils. Hypersensitivity to certain proteins in the diet (gluten and casein) can also cause these symptoms.

If you get constipated, bloated or have diarrhoea, a dietitian can:

  • look at whether your diet is giving you enough fibre and fluid
  • look for signs of food hypersensitivity
  • give dietary advice to ease these symptoms

Gluten and casein hypersensitivity

Gluten is a protein found in wheat, rye and barley and foods made from them, for example bread, pasta, biscuits and breakfast cereals. Casein is a protein found in cow, goat and sheep milks and foods made from them, for example cream, yoghurt and cheese. Hypersensitivity to these proteins may worsen mood, behaviour and communication in some people with autism.

There is not enough evidence to recommend the gluten and casein-free diet for all people with autism but some people do feel better on it.

Changing your diet may appear a safe choice but cutting out lots of foods can make your body miss important nutrients, lose weight and not grow properly. This is especially important if you only eat a small number of foods already.

If you think that certain foods make you feel unwell, a dietitian can:

  • look for signs of food hypersensitivity
  • advise on a nutritionally-balanced gluten and caseinfree diet
  • recommend suitable alternatives and supplements
  • make sure your diet provides all of the nutrients that you need
  • help you decide whether your diet is effective or not


Dietitians can give advice and support for all the dietary problems that affect people with autism. If you, or someone you know, has autism and would like to see a dietitian, here’s how:

  • ask your doctor to refer you onto a NHS dietitian
  • self-refer by calling your local hospital/community health services and asking to speak to the dietetics team
  • find a private dietitian at