King’s College study reveals controversial results on the effects of omega 3 on ADHD symptoms of children

20 Nov 2019 --- A recent study has found that omega 3 supplements improve attention among children with Attention Deficit Hyperactivity Disorder (ADHD), but only among those with pre-existing low levels of omega 3 in their blood. Conversely, the opposite effect occurred testing children with high blood-levels of eicosapentaenoic acid (EPA), the long-chain omega 3 fatty acids. These children presented negative effects of omega 3 supplementation on impulsivity symptoms. Dr. Carmine Pariante, Senior Researcher from the Institute of Psychiatry, Psychology & Neuroscience at King's College London, tells NutritionInsight that this study advocates for a “personalized approach” in such interventions.

“We have always been interested in the role of nutritional interventions in mental health. We have conducted many studies in depression and now we were interested in expanding to other clinical conditions. The evidence supporting a deficiency of omega 3 in ADHD is well established, so this was the natural next step,” he explains.

Dr. Pariante says that although he and his research team anticipated that fish oil would benefit children with lower endogenous levels of omega 3, they were surprised that there was a negative effect. This was worse ADHD impulsivity stemming from the consumption of fish oil in those children with the highest endogenous levels. He calls this having “too much of a good thing.”

“The fact that some children who already have high levels of omega 3 get worse on fish oil is concerning. This research highlights that such nutritional interventions in children with ADHD should only be conducted under proper medical supervision and continuous monitoring of the symptoms,” he clarifies.

Published in the journal Translational Psychiatry, the study was a collaborative endeavor conducted by researchers from King's College London, UK, and China Medical University in Taichung, Taiwan. This 12-week, double-blind, placebo-controlled trial compared the effects of high-dose EPA at a 1.2 g dosage to placebo trials on the cognitive function of participants. The researchers recruited 92 children and adolescents diagnosed with ADHD, aged six to 18 years old, from similar neighborhoods in Taichung, Dr. Jane Chang, one of the study’s researchers, tells NutritionInsight. 

The research team did indeed find a small but meaningful improvement in attention, which is one of the main problems in children with ADHD. This was in all groups, but especially in the children with the lowest endogenous levels of omega 3. However, this did not translate into a measurable improvement as observed by parents and teachers. 

Due to the high fish intake in Southeast Asian diets, ADHD is a relatively uncommon disability found in Taiwan.Criticism of methodology and results
Commenting on the study, some researchers found points of criticism to take into consideration when assessing the effectiveness of fish oil supplementation and alleviating ADHD symptoms. Dr. Jessica Agnew-Blais, Institute of Psychiatry, Psychology & Neuroscience at King’s College London, notes that it is important to recognize that this study did not find any benefit of fish oil supplementation over placebo on ADHD symptom levels or emotional problems among participants. 

Likewise, Professor Graham Burdge, Nutritional Biochemistry at the University of Southampton, criticized the study’s operationalization. He noted that the placebo given to the control group participants included soybean oil, which naturally contains alpha-linolenic acid (ALA), an omega-3 fatty acid that can be converted to EPA. Dr. Chang clarifies that soybean oil actually contains very little alpha-linolenic acid and that it has been estimated that obtaining 1 g EPA requires intake of 20 g pure ALA.

Responding directly to these points of criticism, Dr. Pariante maintains that the main strength of the paper is its providing of a new research approach to correlate the response to fish oil with the measurement of endogenous levels of omega 3. 

Indeed, Professor John Stein, Emeritus Professor of Physiology at the University of Oxford, commented that this study speaks to “many of the problems that bedevil the study of nutrition in psychiatry.” He acknowledges that omega 3 is “a topic of great controversy, but this study begins to answer why omega 3 studies in this area are so contradictory.”

Future research
Dr. Pariante encourages more researchers to replicate the study, either using EPA or other components of fish oil, in other cultural and geographical contexts. As the study was conducted in Taiwan, the typical local diets contain larger amount of fish compared with UK and other Western countries. “As such, we would anticipate that the effects of fish oil in ADHD would be larger in other countries where the dietary habits do not include abundant fish, but this is a hypothesis that needs to be tested,” he illustrates.

Dr. Pariante looks forward to conducting future research based on this study’s findings. “For those children with omega 3 deficiency, fish oil supplements could be a preferable option to standard stimulant treatments,” he explains. This study sets an important precedent for other nutritional interventions and advocates for vocalizing the benefits of “personalized psychiatry” to children with ADHD. 

By Anni Schleicher