In recent years there has been an increasing focus on the role of diet in attention deficit hyperactivity disorder (ADHD), both in children and adults.
The development of ADHD, along with many other mental illnesses, has been linked to nutrition. Research has shown that those with ADHD may be deficient in some vitamins, minerals, and omega-3 fatty acids.
Studies have found a reduction in symptoms when patients have taken daily vitamin and mineral supplements, but the evidence for a benefit is not fully established.
Scientists have reported that various aspects of a child’s diet–including food additives, refined sugars, food allergies and fatty acid metabolism–may have adverse effects on behavior. There is no definitive proof that any of these are responsible for ADHD symptoms, but there is some evidence for a role for omega-3 fatty acids, found in oily fish (such as salmon, herring, mackerel, anchovies and sardines), flaxseeds and linseeds.
Dr. Natalie Sinn of the University of South Australia in Adelaide says that “the current evidence supports nutritional and dietary influences on behavior and learning in children, with the strongest support to date reported for omega-3 fatty acids.”
Omega-3 fatty acids are converted to docosahexaneoic acid which is used mainly in the brain and eyes. A growing number of studies are investigating its relationship with ADHD. Taking supplements often leads to a small benefit compared with placebo. This has led to the suggestion that lack of omega-3 fatty acids affects brain function in such a way as to cause or worsen the symptoms of ADHD.
But in a recent 2010 review, experts from the Netherlands conclude, “There is a theoretical rationale for the effectiveness of fatty acids in the treatment of ADHD. At the moment, however, treatment of ADHD with omega-3 fatty acids is not recommended because it does not qualify as being evidence-based.”
Research has also been conducted on iron, zinc and food sensitivities. Iron deficiency is found in some children with ADHD. It is vital for brain function and individuals with iron-deficiency anemia can experience apathy, depression and fatigue, but tests of supplements are so far inconclusive. Zinc supplements “may be of great benefit” for ADHD, according to one study, but are not conventionally recommended.
A diet high in processed foods and soft drinks may lead to peaks and troughs in blood sugar, triggering periods of hyperactivity. While sugar intake has been linked with hyperactivity in a number of observational studies, more rigorous studies do not support a link.
The question of whether food additives such as preservatives, artificial flavorings, and artificial colorings trigger hyperactivity has been debated for more than 30 years. Research generally has not supported food additives as influencing traits linked to ADHD, but some studies have found small effects.
A 2007 study suggested that the preservative sodium benzoate and several other commonly used artificial food colorings may exacerbate hyperactive behavior in young children. The researchers, from Southampton University, UK, say, “The outstanding feature of the results was the similar pattern of an adverse effect across three-year olds and eight- and nine-year-olds.”
The researchers do not claim that food additives cause ADHD, but the British Food Standards Agency now advises parents to consider eliminating the colorings used in the study from the diets of children who exhibit hyperactive behavior. Further studies are needed to find out whether different additives could have a similar effect, and whether they can also affect ADHD symptoms in adults.
Much of the dietary research on children with ADHD may be of interest to adults with the condition. For example, a 2005 study found that omega-3 supplements improved attention in healthy adults, probably due to their beneficial effect on the central nervous system. A trial of young adult prisoners also found a reduction in antisocial behavior with a supplement that included essential fatty acids.
A further review of research on adults found that “adequate levels of glucose in the blood facilitate attention control.” The researchers say, “Acts of self-control deplete relatively large amounts of glucose. Self-control failures are more likely when glucose is low. Restoring glucose to a sufficient level typically improves self-control.”
Blood glucose is controlled by hormones, but can be negatively affected by lack of food for extended periods, alcohol, very heavy exercise, “stress” hormones such as adrenaline, steroids and infections.
Proper medical diagnosis and a discussion of all possible treatment options should always be the first plan of action when treating ADHD. Psychiatrists need to be aware of the available nutritional therapies, appropriate doses, and possible side effects in order to provide alternative and complementary treatments for their patients.
But the decision on whether to alter diet or try nutritional supplements must be made by the patient or their parent, and as with any form of treatment, nutritional therapy should be supervised and doses should be adjusted as necessary to achieve the best results.
References and Further Reading
Sinn, N. Nutritional and dietary influences on attention deficit hyperactivity disorder. Nutrition Reviews, Vol. 66, October 2008, pp. 558-68.
Barrett, J. R. Diet & nutrition: hyperactive ingredients? Environmental Health Perspectives, Vol. 115, December 2007, p. 578.
Aben, A. and Danckaerts, M. Omega-3 and omega-6 fatty acids in the treatment of children and adolescents with ADHD. Dutch Journal of Psychiatry, Vol. 52, 2010, pp. 89-97.
Ross, B. M., Seguin, J. and Sieswerda, L. E. Omega-3 fatty acids as treatments for mental illness: which disorder and which fatty acid? Lipids in Health and Disease, Vol. 18, September 2007, pp. 6-21.
McCann, D. et al. Food additives and hyperactive behaviour in 3-year-old and 8/9-year-old children in the community: a randomised, double-blinded, placebo-controlled trial. The Lancet, Vol. 370, November 3, 2007, pp. 1560-67.
Fontani, G. et al. Cognitive and physiological effects of Omega-3 polyunsaturated fatty acid supplementation in healthy subjects. European Journal of Clinical Investigation, Vol. 35, November 2005, pp. 691-99.
Gesch, C. B. et al. Influence of supplementary vitamins, minerals and essential fatty acids on the antisocial behaviour of young adult prisoners. Randomised, placebo-controlled trial. The British Journal of Psychiatry, Vol. 181, July 2002, pp. 22-28.
Gailliot, M. T. and Baumeister, R. F. The Physiology of Willpower: Linking Blood Glucose to Self-Control. Personality and Social Psychology Review, Vol. 11, November 1, 2007, pp. 303-27.
Wiles, N. J. et al. “Junk food” diet and childhood behavioural problems: Results from the ALSPAC cohort. The European Journal of Clinical Nutrition, Vol. 63, April 2009, pp. 491-98.
Dodig-Curkovic, K. et al. The role of zinc in the treatment of hyperactivity disorder in children. Acta Medica Croatica, Vol. 63, October 2009, pp. 307-13.