Autism - Food for the Brain

About autism

Autism is a complex condition, characterised by difficulties with social communication, for example struggling to understand what is said and finding it hard to express themselves. Additionally, individuals with autism may have difficulties with social interaction, such as not being able to interpret how others are feeling or to express their own feelings. In recent years, there is a growing body of evidence emerging, which suggests the role that nutrition and lifestyle factors may be a key consideration.

People on the autism spectrum have the following characteristics: 

  • Making repetitive movements, such as hand flapping or rocking, and having restrictive behaviours so that they dislike change but feel more secure when they are able to stick to routines they know.
  • Having ‘special interests’ that absorb their attention and are very important to them
  • Being over-sensitive or under-sensitive to light, sound, taste, touch or taste 
  • Being very anxious because they have difficulty understanding what is going on or what may happen next. 
  • Having meltdowns (tantrums) or shutdowns when they seem to switch off. Both these are caused by feeling overwhelmed, either through sensory overload or when their level of anxiety is more than they can cope with.  

The National Autistic Society estimates that around 700,000 people have autism in the UK with  three times more boys than girls affected1.

No single cause has been established, although genetic, neurodevelopmental and environmental factors are implicated¹. Increasingly, autism is being seen as a difference and part of neurodiversity rather than a disorder. While it cannot be ‘cured’, there are ways of supporting an individual with autism with any difficulties they may have.

There is growing evidence that nutrition and lifestyle interventions can be very supportive to individulas with autism. For example, many individuals with autism have severely disrupted digestion, so restoring balance in the gut is a key focus from a nutritional perspective. The following are also important nutritional and lifestyle factors for consideration:

  • balancing blood sugar
  • exposure to heavy metals (such as Aluminum and Mercury)
  • excluding food additives
  • identifying food allergies, such as gluten and dairy
  • addressing nutrient deficiencies
  • ensuring an optimal intake of essential fats, most notably omega 3 fatty acids

Read on for more information on how autism can be influenced by nutrition.

Nutrition and Autism: Nutritional Approaches 

Improve digestion

Research has identified a possible link between the imbalances in the composition of microbiota in the gut of individuals with autism. This may be linked to symptoms such as irritability and a decreased ability to concentrate, caused by discomfort as a result of digestive issues, such as constipation and/or diarrhoea 2. Notably, many parents of autistic individuals report that their individual has received repeated or prolonged courses of antibiotic drugs, for ear or other respiratory infections, during their first year, before the diagnosis of autism. Broad-spectrum antibiotics kill good as well as bad bacteria in the gut, and this may be why autistic individuals commonly have bowel irregularities.

If your individual has autism, restoring a healthy gut is vital. You can start simply, under the supervision of a doctor, by supplementing digestive enzymes, and giving probiotics to restore the balance of gut bacteria. Both measures may help to restore balance to the digestive tract and promote normal absorption. A recent study indicated that these measures produced positive clinical results in autistic individuals3

Side effects? None reported

Contraindications with medication? Further courses of antibiotics will eliminate beneficial gut bacteria, and continuing to administer probiotics is therefore recommended. 

Key Action:

Take a probiotic: key to digestion is having a balanced gut ecology. This means plenty of beneficial gut flora and lower levels of the non-beneficial strains. As previously discussed, antibiotics may imbalance flora. In addition, individuals who were not breastfed may also have fewer strains of beneficial bacteria, in comparison with breastfed individuals.  Therefore, it is usually necessary to supplement probiotics to increase the presence of beneficial gut bacteria4. The most important strains are Lactobacillus Acidophillus and Bifidobacter. Saccharomyces boulardii,  whilst technically a yeast, not a bacteria, is another important factor, which should be present in the gut, particularly if low levels of Secretory IgA (SIgA) are found in a saliva test.

Supplement with digestive enzymes: Digestive enzymes provide assistance by helping to break down food, making the nutrients more available for absorption and relieving the strain on the digestive system, whilst it recovers. The amino acid glutamine is an important gut healing nutrient but may be contraindicated in autism because some individuals with autism have protein deamination problems, which may lead to production and build up of ammonia6.

Balance blood sugar

There is much overlap between ADHD/hyperactivity and autism, so for autistic individuals who show signs of hyperactivity, improving blood sugar balance is an important consideration. 

Dietary studies consistently reveal that hyperactive individuals eat more sugar than other individuals7. A study of 265 hyperactive individuals found that more than three-quarters of them displayed abnormal glucose tolerance, – that is, their bodies were less able to handle sugar intake and maintain balanced blood sugar levels8.

When a individual is regularly snacking on refined carbohydrates, sweets, chocolate, fizzy drinks, juices and little or no fibre, protein and monounsaturated and polyunsaturated fats, to slow the glucose absorption, the levels of glucose in their blood will seesaw continually. This may cause fluctuations in their levels of activity, concentration, focus and behaviour, and impact on brain function and development9.

Side effects? None reported

Contraindications with medication? Diabetes medication should be closely monitored since dosages may need to be lowered.

Key Action:

Cut out sugar and all sources of refined sugar. Eat only unrefined carbohydrates, such as fresh vegetables and fruit, and ensure these are combined with protein, and monounsaturated and polyunsaturated fats to further slow the sugar release. Avoid stimulants, even apparently ‘natural’ ones, such as caffeine.

Increase omega 3 fats

Deficiencies in essential fats are common in people with autism. Research by Dr Gordon Bell at Stirling University has shown that some autistic individuals have an enzymatic defect that removes essential fats from brain cell membranes more quickly than it should10. This means that autistic individuals are likely to need a higher intake of essential fats. It has been found that supplementing EPA, which can slow the activity of the defective enzyme, has clinically improved behaviour, mood, imagination, spontaneous speech, sleep patterns and focus in autistic individuals. There have since been clinical trials testing omega-3 supplementation, which have found that when individuals with autism were given omega-3 supplements, improvements in symptoms such as hyperactivity, social ability, concentration, irritability and aggression were reported 11,12.

Side effects? Causes loose stools in sensitive individuals if they are started on too high a dose.

Contraindications with medication? Essential fats may have a ‘blood-thinning’ effect and should not be mixed with ‘blood thinning’ medication, such as warfarin or heparin. Always consult your doctor before commencing a new supplement. 

Key Action:

Eat oily fish, such as salmon, mackerel and sardines, at least twice a week, and seeds, such as flaxseeds (also called linseeds) and chia seeds, on most days. Furthermore, supplement omega 3 through fish oil or a vegan alternative. Look for a supplement that contains both EPA and DHA.

The best fish for EPA, the type of omega 3 fat that’s been most thoroughly researched are: mackerel (1,400mg per 100g/3oz), herring/kipper (1,000mg), sardines (1,000mg), fresh (not tinned) tuna (900mg), anchovy (900mg), salmon(800mg), trout (500mg). Tuna, being high in mercury, is best avoided in autism due to heavy metal considerations.

The best seeds are flax seeds and chia seeds. Flax seeds are so small they are best ground and sprinkled on cereal. Alternatively, use flaxseed oil, for example in salad dressings. While technically providing omega 3 only about 5% of the type of omega 3 (alpha linolenic acid) in these seeds is converted in your body into EPA.

Increase vitamins and minerals

Vitamin B6, Vitamin C and Magnesium

We have known since the 1970s that a nutritional approach can help autism, thanks to the pioneering research by Dr Bernard Rimland of the Institute for individual Behaviour Research in San Diego, California. He showed that vitamin B6, C and magnesium supplements significantly improved symptoms in autistic individuals. In one of his early studies back in 1978, 12 out of 16 autistic individuals improved, then regressed when the vitamins were swapped for placebos 14. Other studies, however, have failed to confirm conclusively  positive outcomes with certain nutrients. For example, a French study of 60 autistic individuals found they improved significantly on a combination of vitamin B6 and magnesium, but not when either nutrient was supplemented alone16

Vitamin A

Paediatrician Mary Megson from Richmond, Virginia, believes that many autistic individuals are lacking in vitamin A.Vitamin A is essential for vision. It is also vital for building healthy cells in the gut and brain17. Megson began speculating what might happen if these individuals were not getting enough natural vitamin A. She realised that not only would this affect the integrity of the digestive tract, potentially leading to allergies, but it may also affect brain development and vision. Both brain differences and visual defects have been detected in autistic individuals. The visual defects, Megson deduced, were an important clue because lack of vitamin A may cause poor black and white vision, a symptom often seen in the relatives of autistic individuals. If you cannot see black and white, they cannot see shadows, and without that you lose the ability to perceive three-dimensionality. This in turn leaves you less able to make sense of people’s expressions, which could explain why some autistic individuals tend not to look straight at you, but rather sideways sideways. Long thought to be a sign of poor socialisation, this sideways technique may in fact be the best way for them to see people’s expressions, because there are more black and white light receptors at the edge of the visual field than in the middle of the eye 17

The best sources of vitamin A are breast milk, organ meats, milk fat, fish and cod liver oil, none of which are prevalent in our diets. An important point regarding formula milk, fortified food and multivitamins, is that many of which contain altered forms of Vitamin A such as retinyl palmitate, which doesn’t work as well as the fish or animal-derived Vitamin A. 

Vitamin D

Recent research and clinical trials have highlighted a possible link with autism and vitamin D levels. In a study on individuals with autism, when vitamin D status was compared to their counterparts it was found that individuals with autism had significantly lower vitamin D levels. When individuals were supplemented with vitamin D3 (300iu/kg/day) for 3 months 80% of participants had significantly improved symptoms such as attention span, eye contact, behaviour 13 .

Side effects? High doses of any nutrient (even water) can be toxic so it is best to only use high doses under qualified supervision. However, usual over-the-counter doses of vitamins and minerals are very safe.

Contraindications with medication? None reported

Key Action:

Eat a diet rich in whole foods such as fresh fruit and vegetables, seeds, nuts and whole grains is naturally higher in vitamins and minerals. Avoid processed foods that have had many nutrients removed.

Avoid food allergies

One of the most significant contributing factors in autism appears to be undesirable foods and chemicals that often reach the brain via the bloodstream because of faulty digestion and absorption. Much of the impetus for recognising the importance of dietary intervention has come from parents who have noticed vast improvements in their individuals after changing their diets.

The strongest direct evidence of foods linked to autism involves wheat and dairy, and the specific proteins they contain – namely, gluten and casein. These are difficult to digest and, especially if introduced too early in life, may result in an allergy. Fragments of these proteins, called peptides, can have a major impact on the brain. They can act directly in the brain by mimicking the body’s own natural opioids (such as the enkephalins or endorphins), and so are sometimes called ‘exorphins’. Or they can disable the enzymes that would break down these naturally occurring compounds. In either case, the consequence is an increase in opioid activity, leading to many symptoms we describe as autism. Researchers at the Autism Research Unit at Sunderland University have found increased levels of these peptides in the blood and urine of individuals with autism18.

Exorphin peptides are derived from incompletely digested proteins, particularly food containing gluten and casein. One of these, called IAG, is derived from gluten in wheat,  and has been detected in 80 per cent of autistic patients. An initial issue is the poor digestion of proteins, although it should be noted that a lack of sufficient zinc and vitamin B6 could contribute to this, as both are essential for proper stomach acid production and protein digestion, yet are often deficient in autistic individuals19. Dr Robert Cade, professor of medicine and physiology at the University of Florida, has observed that as levels of peptides in the blood decrease, some symptoms of autism may decrease. ‘If [levels of peptides] can be reduced to normal range,’ he says, ‘we typically see dramatic improvements.’

If you decide to go down this route with your individual, you’ll need to take a slow approach. The Autism Research Unit at Sunderland University recommends a gradual withdrawal of foods, waiting three weeks after the removal of dairy foods (casein) before removing wheat, barley and rye (gluten) from the diet. Initially, your individual may go through ‘withdrawal’ and their symptoms may get worse for a bit.

Keep a food diary and note your individual’s behaviours and symptoms alongside all the foods they’re eating. This can help to identify which of the usual suspects they are sensitive to – citrus fruits, chocolate, artificial food colourings, salicylates, eggs, tomatoes, avocados, aubergine, red peppers, soya and corn. But remember, most of the foods in this list contain valuable nutrients, too, so you’ll have to ensure that they are replaced rather than just removed. This entire process is best done under the guidance of a doctor and a qualified nutritionist or dietitian21.

Side effects? A possible slight worsening of symptoms if changes are made too quickly. Any major changes to the diet are should be supervised by a qualified nutritional therapist experienced in this area.

Contraindications with medication? None reported

Key Action:

Consider testing your individual for food allergies and avoid those foods to which they test allergic. Alternatively, consider pursuing a wheat and dairy free diet which has proven helpful for some, but not all, autistic individuals. However we recommend you do so under medical supervision, or supervision of a dietitian or nutrition to ensure that suitable replacement foods are included that ensure your individual achieves optimal nutrition.

Researcher: Ellie Winch, MSc Global Public Health Nutrition

Reviewed by: Dr Rona Tutt, PhD & OBE and Alice Benskin, Msc Personalised Nutrition

Published: October 2021

Next due for review: October 2022


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