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Omega 3 Fatty Acid Supplements and Autism Ranking: Insufficient/Mixed evidence

Omega 3 fatty acid capsules

Omega-3 fatty acids are essential fatty acids (EFA), essential to good health.  They cannot be created within the human body and must therefore be obtained from the diet.

Some people think that individuals on the autism spectrum either do not have enough omega-3 or have too much omega-6 in relation to omega-3 in their bodies.

They think that this may cause or worsen some of the symptoms of autism, such as impaired communication and social difficulties.

They also think that these difficulties can be overcome by increasing the amount of omega 3 in the diet or by taking supplements (such as fish oils) which are rich in omega-3.

Please note

The National Institute of Health and Care Excellence (NICE) made the following recommendations:
 
“Do not use omega-3 fatty acids to manage sleep problems in children and young people with autism.” (NICE, 2013).

Our Opinion

There is a very small amount of high quality research evidence (13 group studies) and a small amount of low quality research (three single-case design studies with three or more participants) into the use of omega-3 fatty acids as an intervention for people on the autism spectrum.

Some of those studies have reported benefits (such as increased social communication and interaction and decreased hyperactivity). Some of those studies have reported no benefits of any kind.

There is therefore insufficient evidence to determine if omega-3 fatty acids provide any benefits to anyone on the autism spectrum. 
Omega-3 is relatively cheap to obtain and relatively easy to administer, either as a supplement or as part of a diet.

Given the number of anecdotal reports of the benefits of omega-3 fatty acids, we recommend that further large scale, high quality research should take place.

Disclaimer

Please read our Disclaimer on Autism Interventions


Aims and Claims

Aims

The aim of taking omega-3 fatty acid supplements is to treat any omega-3 fatty acid deficiency and to increase the amount of omega-3 relative to the amount of omega-6. Some people think this will affect the balance of fatty acids in cell membranes, which could affect brain function and mental health.

Omega -3 fatty acid supplements have been used as a treatment for a range of conditions including in the prevention of heart disease and in some inflammatory disorders.

Claims 

There have been various claims made for essential fatty acids and individuals on the autism spectrum. For example, the following researchers have made the following claims

  • Amminger et al. (2007) reported that omega-3 fatty acids reduced hyperactivity and stereotypy in seven autistic children who were treated for eight weeks.
  • Bell et al (2004) reported that omega-3 fatty acids led to improvements in overall health, cognition, sleep patterns, social interactions and eye contact in 18 autistic children who were treated for six months.
  • Meguid et al (2008) reported that omega-3 fatty acids improved concentration, eye contact, language development and motor skills in 30 autistic children who were treated for three months.

In addition, there have been a number of anecdotal claims for the benefits of essential fatty acids including Patrick and Salik (2005) who reported significant improvements in language and learning skills.

Audience

The supporters of omega 3 EFA supplements claim that they are suitable for anybody, including individuals with autism.

Key Features

What are fatty acids?

Fatty acids are components of fats in our food. Dietary fats not only provide a source of energy for our bodies, but also affect many different aspects of our health. Fatty acids are present in every cell in our bodies and play important roles in heart health, immunity and hormone responses.

Fatty acids are classified as saturated, monounsaturated or polyunsaturated depending on their molecular structure. Essential fatty acids (EFAs) are polyunsaturated fatty acids that cannot be created within the human body and must therefore be obtained from the diet.

There are 2 different families of EFAs – the omega-3 fatty acids and the omega-6 fatty acids.

Omega-3 fatty acids

There are a number of different forms of omega-3 fatty acid including alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

ALA is found in rapeseed, linseed (flaxseed) and soybean oils, and spreads made from these oils. It is also found in ground linseeds, soyabean products, walnuts, and dark green leafy vegetables.

EPA and DHA are found in the flesh of oily fish such as salmon, herring, mackerel, anchovies and sardines, and in fish oil supplements including cod liver oil.

Omega-3 enriched products such as bread, eggs and milk are also widely available.

Omega-6 fatty acids

There are a number of different forms of omega-6 fatty acid including linoleic acid (LA) and arachidonic acid (AA).

LA is found in safflower, sunflower, hemp and soybeans, and AA is abundant in typical Western diets in vegetable oils, nuts, cereals and animal fats.

The importance of balance

The typical Western diet contains much more omega-6 fatty acids than omega-3s. This fatty acid imbalance in our typical diet is thought to have many different negative health effects, including on our mental health and brain function. However, as Innes et al (2018) have noted “The interaction of omega-3 and omega 6 fatty acids … in the context of inflammation is complex and still not properly understood”

How can they be taken?

Fish oil supplements rich in the omega-3 fatty acids DHA and EPA are widely available from pharmacists, supermarkets and mail order companies. They are available as liquids, capsules and chewable tablets.

Omega-3 fatty acids can be incorporated into a normal diet by eating two portions of fish per week, one of which should be oily fish, and by eating more green leafy vegetables, soya beans and linseed.

Notes

Monounsaturated (fat molecules that have one unsaturated carbon bond in the molecule); polyunsaturated (fat molecules that have more than one unsaturated carbon bond in the molecule); saturated (fat molecules that have no double bonds between carbon molecules because they are saturated with hydrogen molecules).

Cost and Time

Cost

The cost of buying omega-3 supplements depends on a range of factors including the type of supplement, the quantity you buy, the supplier, delivery charges etc.

We found a wide range of suppliers providing omega-3 supplements for a wide range of prices when we did an online search on 9 May 2018. Prices varied from £2.87 for 120 tablets to £75 for 250 tablets.   

In the UK, it is sometimes possible to obtain free NHS prescriptions for specific dietary supplements if you have certain medical conditions (such as diabetes) or you are a member of an exempt group (such as being under 16 or over 65).   

Time

The amount of time it takes to use omega-3 supplements will depend on a number of factors including the overall length of treatment, the frequency of treatments and the time taken to administer a single dose, as well as the needs of the person undertaking it.

Most omega-3 supplements are designed to be taken once or twice a day, often before mealtimes.

Some researchers suggest that daily omega-3 supplements should be taken for at least 3 months for full effects to be seen. Daily supplementation is generally quick and easy but young children are often reluctant to take supplements.

We would strongly recommend that you review your use of dietary supplements on a regular basis with a responsible health professional such as a dietitian, GP or pharmacist. This is because you are likely to experience some harm if you take supplements in large amounts over long periods of time.

Risks and Safety

Hazards

The quality of omega-3 supplements can vary enormously depending on the specific supplement, the manufacturer, the ingredients and the manufacturing process.  

Omega-3 supplements are generally safe, however we recommended that you discuss the safe trial of any nutritional supplements with your doctor before using them. We also suggest that you do not exceed the RIs (Reference Intakes) recommended by the Food Standards Agency in UK or the RDAs (Recommended Dietary Allowances) recommend by the Office of Dietary Supplements in the USA. 

Particular care is recommended to:
1. Avoid toxins such as mercury, hormones, dioxins, and PCBs, which are present in many fish oils. Supplements are available that have been purified by molecular distillation and which are described as pharmaceutical grade.
2. Avoid toxic doses of vitamin A, which is often included in fish oil supplements. Care should be taken to keep intake within the safe dose as recommended by the UK Department of Health, taking into account vitamin A levels in any additional supplements taken.
3. Avoid supplements containing any ingredients which you or your child or client are allergic or hypersensitive to.
4. Be wary of doses above 1000mg (1 gram) of omega-3 per day.
5. Be aware that fish oils supplements can affect blood sugar control in diabetes.
6. Be aware that high levels of fish oil supplementation can cause blood thinning, which could cause problems in people who bruise easily, self-harm, have a bleeding disorder, or take blood-thinning medications.
Side effects of taking fish oils can include repeating taste, heartburn, diarrhoea, and headaches.

Contraindications

There are very few contraindications (something which makes a particular treatment or procedure potentially inadvisable) for omega-3 fatty acid supplements.

However the National Institutes for Health (2017) noted that

“Omega-3 dietary supplements may interact with the medications you take. For example, high doses of omega-3s may cause bleeding problems when taken with warfarin … or other anticoagulant medicines.”

Notes

Dioxins (toxic chemical by-products of industrial processes); PCBs (polychlorinated biphenyls, synthetic organic chemicals that can cause a number of different harmful effects.)

Suppliers and Availability

Suppliers 

Omega-3 supplements are available from a wide range of suppliers including health food stores, chemists and pharmacies, professional health care providers and online stores. 

If you are contemplating taking omega-3 supplements, you should seek advice from a GP, pharmacist or dietitian. The British Dietetic Association has information about qualified dietitians in the UK.

For children and adults who are not eating a varied and sufficient diet, for example, avoiding food groups, or eating a very restricted diet, a dietitian can help by assessing dietary intake and advising on testing and supplementation where necessary. 

All professionals involved with adults and children on the autism spectrum should watch for potential nutritional problems particularly if their diets are restricted. 

Credentials

There are no formal, internationally validated registered qualifications for most people who provide omega-3 supplements.   

However, in the UK, the quality of dietary supplements is regulated by the Medicines and Healthcare Products Regulatory Agency, if they ‘contain a pharmacologically active substance or make medicinal claims (claims to treat or prevent disease, or to interfere with the normal operation of a physiological function of the human body) ...’

In the UK certain supplements are considered to be foods and will therefore be regulated under general food laws by the Food Standards Agency and Department of Health. Others will be regulated as a medicine by the Medicines and Healthcare Regulatory Agency (MHRA).

All herbal medicines placed on the UK market must have a Traditional Herbal Registration (THR)10 or a marketing authorisation (previously known as a product licence). The MHRA now defines individual herbal medicines as either registered traditional herbal medicines or licensed herbal medicines.

In the USA dietary supplements are not classed as drugs, but the Food and Drug Administration is responsible for taking action against any unsafe dietary supplement product after it reaches the market. 

History

Essential fatty acids were discovered in 1920's, when they were called vitamin F. They were re-classified as fats in 1930.

Essential fatty acids began to be used for the treatment of various mental health problems, such as depression and schizophrenia, in the 1990s. They began to be used for the treatment of autism in the 2000s.

 

Current Research

Description of the studies

We have identified 16* articles published in English-language, peer-reviewed journals which evaluated the efficacy of omega-3 fatty acids as an intervention for people on the autism spectrum.  Three of those articles (Boone et al, 2017; Keim et al 2018; Sheppard et al, 2017) appeared to describe the same study.

The studies we found included more than 300 individuals aged from three to forty - but only one of these studies looked at adults, the majority looked at children and adolescents. A small number of studies also included people with other conditions, such as ADHD.

The majority of the group studies were randomised controlled trials which compared omega-3 supplements with a placebo. One of the studies (Meguid et al, 2008) used a supplement which included omega-6 alongside the omega-3. Another of the studies (Boone et al, 2017) used a supplement which included omega-6 and omega-9 alongside the omega-3. One of the randomised controlled studies (Johnson et al, 2010) compared omega-3 with a sugar-free diet. The four single case designs were open trials which did not compare omega-3 with anything else.

The length of intervention varied from six weeks to 16 weeks but in most cases it lasted between six weeks and three months. The dosage varied from 0.09 grams per day to 1.5 grams per day but in most cases the dosage varied between 1and 1.5 grams per day.

*Please note: We have not included articles with less than three participants on the autism spectrum or articles which did not examine the efficacy of omega-3 fatty acids as an intervention for people on the autism spectrum.

Study Outcomes

  • Some of the studies (such as Parellada et al, 2017) reported significant benefits including improvements in communication and social interaction.
  • Some of the studies (such as Bent et al, 2011) reported limited benefits (such as improvements in hyperactivity) but these benefits did not reach statistically significant levels.
  • Some of the studies (such as Voight et al, 2014) reported no benefits.
  • One study (Mankad et al., 2015) reported no benefits and a worsening of symptoms in some participants.

Status Research

There are a number of limitations to all of the research studies published to date. For example

Type of study

  • Four of the studies used single-case designs, that is, they did not have a control group of participants who did not receive the omega-3.

Participants

  • Five of the group studies and two of the single case designs included fewer than 30 participants. For example, the randomised controlled study by Amminger et al (2007) only had 13 participants.
  • Most of the studies were restricted to specific groups of participants. For example one study (Voigt et al, 2014) looked only at children aged two to five diagnosed with autistic disorder.
  • One of the studies (Yui et al, 2012) included participants from a wide age-range (six to 28 years old) with a range of diagnoses (Asperger syndrome and autistic disorder).
  • One of the studies (Johnson et al, 2009) examined 75 participants with ADHD, only 23 of whom were also on the autism spectrum. 
  • One of the studies (Boone et al, 2017) examined infants “at risk” of autism so could not verify the diagnosis of autism using established diagnostic tools like the ADOS or ADI-R. 

Intervention/s

  • Some of the studies examined supplements containing a range of omega-3 fatty acids while others only examined supplements containing one type of omega-3 acid, making it difficult to know if any effects were caused by one or more specific acids.
  • One of the studies examined a supplement which combined omega-3 with omega-6 and one of the studies examined a supplement which combined omega-3 with omega-6 and omega-9. This makes it difficult to know if any effects were caused by the omega-3, the omega-6, the omega-9 or all of them.
  • In one of the studies (Bent et al, 2014) only 69% of the doses of omega-3 were actually taken by the experimental group, which is a very poor adherence rate.
  • Many of the studies ran for relatively short periods of time (six to eight weeks). 
  • One of the crossover studies (Parellada et al, 2017) had a relatively brief wash out period (two weeks) between the omega-3 and the placebo.

Comparators

  • One of the controlled studies (Meguid et al, 2008) compared a group of autistic participants who received omega-3 with a group of non-autistic participants who also received omega-3, rather than with a group of autistic participants who did not receive the omega-3.
  • One of the studies (Amminger et al, 2007) had much higher scores for hyperactivity and repetitive behaviours in the experimental group than the control group at the start of the treatment. This means that the decreases in hyperactivity in the experimental group reported at the end of the study may have been due to a statistical effect called “regression to the mean” rather than to a real treatment effect.

Outcomes

  • Some of the studies (such as Amminger et al, 2007) did not provide any data on the fatty acid levels of the participants at the beginning or end of the intervention.
  • Some of the studies (such as Meguid et al, 2008) did not provide any data on any adverse or harmful effects.
  • In one of the studies (Politi et al, 2008) a single outcome measure that is not widely known was used (the Rossago Behavioral Checklist).
  • One of the studies (Meiri et al, 2009) provided data from one of the outcome measures (ATEC) but did not provide any data from the other outcome measures (CARS, CGI, CPRS).
  • In one of the studies (Bent et al, 2014) the reported outcomes were based on parent and teacher observation but there were was no direct clinical observation by the therapists. 
  • Some of the studies (such as Johnson C. et al, 2010) did not provide any information on the effect size of the intervention.
  • Some of the studies (such as Meiri et al, 2009 did not provide any kind of statistical analysis of the outcomes (such as statistical significance or confidence intervals).
  • Some of the studies (such as Bent et al, 2011) reported limited benefits (such as improvements in hyperactivity) but these benefits did not reach statistically significant levels.
  • Most of the studies did not undertaken any kind of follow up to identify if omega-3 had any beneficial or harmful effects in the medium to long term (six months or longer).

Other

  • Very few of the studies appeared to involve people on the autism spectrum and parents and carers in the design, development and evaluation of those studies.

Ongoing Research

  • Massey University, Auckland is running a study to investigate the effect of supplementing omega-3 and vitamin D in the diet of young children with autism spectrum disorder.  Clinical Trials Gov Ref: ACTRN12615000144516.  For more details, please see Effect of Vitamin D and Omega-3 Fatty Acid Supplements on behavioural measures in Children with Autism Spectrum Disorder (ASD): A randomised, double-blind, placebo-controlled trial Full Item (Open in New Window) 
  • National Healthcare Group, Singapore is running a study to determine whether omega-3 fatty acids are effective in reducing the severity of autism and its comorbidities.  Clinical Trials Gov Ref: NCT01695200.  For more details, please see Omega-3 Fatty Acids in Autism Spectrum Disorders Full Item (Open in New Window)
  • The University of Medicine and Dentistry New Jersey and the National Center for Complementary and Alternative Medicine (NCCAM) are running a trial into the use of omega 3 fatty acids for people with autism spectrum disorders. Clinical Trials Gov Ref: NCT00467818.  For more details, please see Omega 3 fatty acids in the treatment of children with autism spectrum disorders Full Item (Open in New Window)

Future Research

Summary of Existing Research

There is a very small amount of high quality research evidence (13 group studies) and a small amount of low quality research (three single-case design studies with three or more participants) into the use of omega-3 fatty acids as an intervention for people on the autism spectrum.

Some of those studies have reported benefits (such as increased social communication and interaction and decreased hyperactivity). Some of those studies have reported no benefits of any kind.

There is therefore insufficient evidence to determine if omega-3 fatty acids provide any benefits to anyone on the autism spectrum. 

Recommendations for Future Research

There is a need for further research into the use of omega-3 fatty acid supplements for people on the autism spectrum.  Specifically there is a need for studies which

  • Use robust methodology, for example, large-scale, placebo-controlled, randomised, double-blind trials 
  • Provide data on the fatty acid levels of the participants at the beginning or end of the intervention.
  • Use standardised outcome measures at the start and at the end of the trials and give equal prominence to all of those measures in the reporting of the trials.
  • Use appropriate statistical tests and techniques to analyse the data.
  • Identify which individuals, if any, are most likely to benefit from which formulations and dosages.
  • Determine if omega-3 supplements can be used as one of the elements within comprehensive, multi-component, treatment models, for example, alongside special diets.
  • Compare omega-3 supplements with other interventions which are designed to achieve similar results, such as special diets.
  • Identify if omega-3 supplements have any beneficial or harmful effects in the medium to long term. 
  • Involve people on the autism spectrum in the design, development and evaluation of those studies. 

Studies and Trials

This section provides details of scientific studies into the effectiveness of omega-3 for people on the autism spectrum which have been published in English-language, peer-reviewed journals. You may be able to find more studies on omega-3 in our publications database.

If you know of any other studies we should include in this section or in our publications database please email info@researchautism.net with the details. Thank you.

Please note that we are unable to supply publications unless we are listed as the publisher. However, if you are a UK resident you may be able to obtain them from your local public library, your college library or direct from the publisher.

Related Studies and Trials


Other Reading

This section provides details of other publications on this topic. If you know of any other publications we should include please email info@researchautism.net with the details. Thank you.

Please note that we are unable to supply publications unless we are listed as the publisher. However, if you are a UK resident you may be able to obtain them from your local public library, your college library or direct from the publisher.

Related Other Reading


Updated
14 Dec 2018
Last Review
01 Dec 2018
Next Review
01 Dec 2021