research suggests that for some people, dietary changes can improve symptoms.
In fact, a substantial amount of research has examined how nutrition affects ADHD.
What Is ADHD?
Attention deficit hyperactivity disorder (ADHD) is a behavioral condition involving inattention, hyperactivity and impulsiveness.
It’s one of the most common disorders children can have, but also affects many adults.
The exact cause of ADHD is unclear, but research shows that genetics play a major role. Other factors, such as environmental toxicity and poor nutrition during infancy, have also been implicated.
ADHD is believed to originate from low levels of dopamine and noradrenaline in the region of the brain responsible for self-regulation.
When these functions are impaired, people struggle to complete tasks, perceive time, stay focused and curb inappropriate behavior.
This, in turn, affects the ability to work, do well in school and maintain appropriate relationships, which can decrease quality of life.
ADHD is not considered to be a curable disorder, and treatment instead aims to reduce symptoms. Behavioral therapy and medication are mostly used.
However, dietary changes may also help manage symptoms.
The science behind food’s effects on behavior is still quite new and controversial. However, everyone can agree that certain foods do affect behavior.
For example, caffeine can increase alertness, chocolate can affect mood and alcohol can totally change behavior.
Nutritional deficiencies can also affect behavior. One study concluded that taking a supplement of essential fatty acids, vitamins and minerals led to a significant reduction in antisocial behavior, compared to a placebo.
Vitamin and mineral supplements can also reduce antisocial behavior in children, and poly-unsaturated fatty acids have been shown to decrease violence.
Since foods and supplements have been shown to influence behavior, it seems plausible that they could also affect ADHD symptoms, which are largely behavioral.
For this reason, a good amount of nutrition research has looked into the effects of foods and supplements on ADHD.
Mostly, two types of studies have been performed:
- Supplement studies: Supplementing with one or several nutrients.
- Elimination studies: Eliminating one or several ingredients from the diet.
Supplement Studies: A Research Review
Many studies have shown that children with ADHD often have unhealthy eating habits or nutrient deficiencies.
This caused researchers to speculate that supplements might help improve symptoms.
Nutrition studies have looked into the effects of several supplements on ADHD symptoms, including amino acids, vitamins, minerals and omega-3 fatty acids.
Amino Acid Supplements
Every cell in your body needs amino acids to function. Among other things, amino acids are used to make neurotransmitters, or signaling molecules in the brain.
In particular, the amino acids phenylalanine, tyrosine and tryptophan are used to make the neurotransmitters dopamine, serotonin and norepinephrine.
People with ADHD have been shown to have problems with these neurotransmitters, as well as low blood and urine levels of these amino acids.
For this reason, a few trials have examined how amino acid supplements affect ADHD symptoms in children.
Tyrosine and s-adenosylmethionine supplements have provided mixed results, with some studies showing no effects and others showing modest benefits.
Vitamin and Mineral Supplements
Iron and zinc deficiencies can cause cognitive impairment in all children, whether or not they have ADHD.
However, lower levels of zinc, magnesium, calcium and phosphorous have repeatedly been reported in children with ADHD.
Several trials have looked into the effects of zinc supplements, and all of them reported improvements in symptoms.
Another two trials assessed the effects of iron supplements on children with ADHD. They also found improvements, but again, more research is needed.
The effects of mega-doses of vitamins B6, B5, B3 and C have also been examined, but no improvements to ADHD symptoms were reported.
Nevertheless, a 2014 trial of a multivitamin and mineral supplement did find an effect. The adults taking the supplement showed a convincing improvement on ADHD rating scales after 8 weeks, compared to the placebo group.
Omega-3 Fatty Acid Supplements
Omega-3 fatty acids play important roles in the brain.
Children with ADHD generally have lower levels of omega-3 fatty acids than children who don’t have ADHD.
What’s more, the lower their omega-3 levels, the more learning and behavioral problems the ADHD children seem to have.
Therefore, it’s not surprising that many studies have found omega-3 supplements to cause modest improvements to ADHD symptoms.
In studies, omega-3 fatty acids appear to help improve task completion and inattention. Additionally, they decreased aggression, restlessness, impulsiveness and hyperactivity.
People with ADHD are more likely to have adverse reactions to food, which caused speculation that eliminating problematic foods might help improve symptoms.
Studies have examined the effects of eliminating many ingredients, including food additives, preservatives, sweeteners and allergenic foods.
Eliminating Salicylates and Food Additives
By accident, an allergist named Dr. Feingold discovered that food could affect behavior.
In the 1970s, he prescribed a diet for his patients that eliminated certain ingredients that produced a reaction for them.
The diet was free of salicylates, which are compounds found in many foods, medications and food additives.
While on the diet, some of Feingold’s patients noted an improvement in their behavioral problems.
Soon after, Feingold started recruiting children diagnosed with hyperactivity for dietary experiments. He claimed that 30–50% of them improved on the diet.
His work was celebrated by many parents, who formed the still-existent Feingold Association of the United States.
Although reviews concluded the Feingold diet was not an effective intervention for hyperactivity, it stimulated further research into the effects of food and additive elimination on ADHD.
The Few Foods Elimination Diet
The Few Foods Elimination Diet is a method that tests how people with ADHD respond to foods. Here’s how it works:
- Elimination: Follow a very restricted diet of low-allergen foods that are unlikely to cause adverse effects. If symptoms get better, enter the next phase.
- Reintroduction: Foods suspected of causing adverse effects are reintroduced every 3–7 days. If symptoms return, the food is identified as “sensitizing.”
- Treatment: A personal dietary protocol is prescribed. It avoids sensitizing foods as much as possible, in order to minimize symptoms.
Twelve different studies have tested this diet, each of which lasted 1–5 weeks and included 21–50 children.
Eleven of the studies found a statistically significant decrease in ADHD symptoms in 50–80% of the participants, while the other one found improvements in 24% of the children.
Of the children who responded to the diet, most reacted to more than one food. While this reaction varied by individual, cow’s milk and wheat were the most common offenders.
The reason why this diet works for some children and not others is unknown.
