The use of nutritional supplements is common in children with ADHD despite limited evidence for their effectiveness. These supplements include macronutrients such as proteins, fats and carbohydrates, as well as micronutrient vitamins and minerals. In clinical trials, few supplements were found of high quality, and study results are frequently inconsistent. The following is a review of the most studied supplements used for ADHD.
Macronutrients for ADHD
Essential Fatty Acids. The essential fatty acids (EFAs) include the following:
- Omega-3 fatty acids
- Eicosapentaenoic - EPA
- Docosahexaenoic acid - DHA
- Omega-6 fatty acids
- Arachidonic acid - AA
- Gamma linolenic acid - GLA
Children with ADHD may have low levels of EFAs, especially DHA and AA. While there have been a number of well designed studies of EFAs in children with ADHD, there is limited evidence that fatty acids improve core symptoms in such children.
A 2011 review of studies that compared the effects of omega-3 supplementation with placebo found that omega-3 was modestly effective on inattentive and hyperactivity ADHD symptoms, especially with a higher doses.
Overall, a growing body of evidence supports the use of an EFA supplement for children who have ADHD. Since there are a number of studies showing positive effects, and the risk of using EFA supplements is low, it is reasonable to embark on a trial of EFAs - especially when parents are ambivalent about medications, or medications are not effective or poorly tolerated.
It is best to use combination EFAs, such as fish oil. Fish oil is a more efficient source of EFAs than flaxseed oil. Fish oil is inexpensive and comes in a variety of flavors and chewables for children. Look for a label that specifies that the product is mercury free. An acceptable dose is 1,000 mg to 2,000 mg (with at least 500 mg EPA) per day from preschool age and up, such as
this one from Amazon.
At least three months should be allowed to see results, and results may be optimal at six months. The most common side effects of fish oil include abdominal pain, belching, and a fishy aftertaste.
L-Carnitine and Acetyl L-Carnitine (ALC). L-carnitine is synthesized from lysine and methionine amino acids. The evidence to support use of L-carnitine is weak at this time. There is some, albeit weak, evidence that patients with inattentive subtype of ADHD responded better than others. Doses used in research were 500 mg to 1,500 mg twice a day and there were no safety concerns or side effects reported.
Micronutrients for ADHD
Zinc. Zinc is an essential mineral and is a cofactor of many enzymes. Zinc deficiency symptoms include concentration impairment and jitters. Several studies suggest that zinc levels may be low in children with ADHD. There is also some evidence that optimal response to stimulant medications might depend on adequate baseline zinc levels.
There is currently no evidence backing zinc supplements as a sole treatment of ADHD. However, zinc supplementation in those patients with suspected zinc deficiency may improve the patient's response to ADHD stimulant medications. Zinc might be more effective for older children with a higher body mass index, and higher doses such as zinc glycinate 15 mg twice a day might be more effective.
Iron. Some studies have found that children with ADHD have lower serum iron levels and that severity of symptoms correlates with lower levels; but other studies found no association. In addition, two studies suggest that iron deficiency might decrease the effectiveness of psychostimulant treatment.
Similar to zinc, taking iron orally might improve symptoms of ADHD in children with iron deficiency. The adverse effects of iron supplementation include abdominal pain, constipation, and vomiting.
Megavitamins
Megavitamin doses are several orders of magnitude greater than the recommended daily allowance (RDA). There is evidence that these large vitamin doses can increase chances of liver toxicity. Moreover, several studies have shown no benefits of megavitamin doses on ADHD symptoms. Due to the potential risk and lack of demonstrated benefits, megavitamin treatments are not recommended. If patients are using doses of vitamins or minerals higher than the recommended daily allowance, it is important to monitor serum or cell membrane levels of these nutrients and liver enzymes to avoid toxicity.
Multivitamins
Many children with ADHD do not eat a balanced diet, or are picky eaters, or have appetite suppression from psychostimulant medications. In any of these cases, the use of a multivitamin supplement at regular RDA doses can be recommended for those at risk for nutritional deficiencies.
Summary
At this time, the evidence for use of nutritional supplements for the treatment of ADHD is limited. Treatments with the best evidence include omega-3 and omega-6 fatty acid combinations (such as in fish oil), zinc as an adjunct to stimulant treatment, iron for children with iron deficiency, and multivitamins for children at risk for nutritional deficiencies. It is important to have an open-minded attitude that invites discussion with parents of their use of alternative medicine treatments.