Attention deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder characterized by inattention, hyperactivity and impulsivity. It often begins in childhood and can persist into adulthood. The exact causes of ADHD are unknown, but research suggests that genetics, environmental factors and neurotransmitter abnormalities in the brain may play a role.
In recent years, some have proposed that vitamin or nutrient deficiencies may also contribute to ADHD in some individuals. Proponents argue that vitamins and minerals play critical roles in cognitive function and brain health, so deficiencies could worsen ADHD symptoms. This article reviews the evidence on whether lack of key vitamins may be linked to ADHD.
Vitamins and Brain Health
Vitamins are essential micronutrients that the body needs in small amounts for various processes. Many vitamins play important roles in brain development, function and mental health. Here is an overview of the main vitamins involved:
Vitamin B6
Vitamin B6 (pyridoxine) is involved in over 100 enzyme reactions in the body, many of which are related to neurotransmitter synthesis and function. Animal studies show B6 deficiency can alter levels of neurotransmitters like serotonin, dopamine, GABA and glutamate in the brain. This provides a potential mechanism for how low B6 could impact attention, behavior and cognition.
Vitamin B9 (Folate)
Folate (vitamin B9) plays a key role in single carbon transfer pathways involved in neurotransmitter production and DNA synthesis. Folate also appears to regulate gene expression in the brain’s reward pathways. Studies in animals and humans indicate that folate deficiency can lead to reduced neurotransmitter levels, DNA damage and other changes that may impair mental function.
Vitamin B12
Vitamin B12 is needed to recycle homocysteine back to methionine. Elevated homocysteine resulting from B12 deficiency may be neurotoxic. B12 is also required for myelin synthesis and neurotransmitter production. Symptoms of vitamin B12 deficiency include problems with memory, depression, confusion and fatigue.
Vitamin C
In addition to its antioxidant functions, vitamin C is needed for neurotransmitter synthesis and modulation of their receptor activity. It also influences neuronal development and function. Low vitamin C levels have been associated with depression, anxiety and cognitive decline in some studies.
Vitamin D
Vitamin D is now recognized to be a hormone with receptors present in neurons and glial cells throughout the brain. It regulates neurotrophic factors, neurotransmission, neuroplasticity, and neuroimmunomodulation. Studies link low vitamin D to cognitive impairment, behavioral problems, and brain abnormalities.
Vitamin E
Vitamin E has antioxidant properties that help protect the brain from oxidative damage. It may also influence signaling pathways involved in neurotransmission, inflammation, and cognition. Vitamin E deficiency could theoretically contribute to psychiatric disorders and dementia risk. However, evidence from supplementation trials has been inconsistent.
Overall, it’s clear that vitamins play integral roles in the brain andinfluence neurological function. Deficiencies could plausibly contribute to ADHD by altering neurotransmitter activity, gene expression, myelination, inflammation, and other processes in the brain. But does evidence actually link low vitamin levels to ADHD?
Evidence Linking Vitamin Deficiencies to ADHD
A number of observational studies have found associations between vitamin deficiencies and ADHD:
Vitamin B6
– A study in 120 children found that those with ADHD had significantly lower levels of vitamin B6 compared to healthy controls.
– Another study measured B6 levels in 52 children with ADHD. 30% were deficient compared to none of the healthy children. B6 deficiency was associated with more severe inattention and hyperactivity/impulsivity symptoms.
– Multiple other studies have also noted lower serum B6 levels in children with ADHD compared to controls.
Folate
– A case-control study in 97 ADHD children found significantly lower serum folate levels compared to healthy controls. Folate deficiency was present in 38% of children with ADHD.
– Another study found children with ADHD had 22% lower red blood cell folate levels on average compared to non-ADHD controls. Folate levels were negatively correlated with hyperactivity symptoms.
Vitamin B12
– One study measured B12 levels in 50 ADHD children. 34% were deficient compared to 6% of healthy children. Lower vitamin B12 was associated with more severe inattention.
– Another study found young adults with ADHD had significantly lower serum B12 levels compared to those without ADHD.
Vitamin D
– Multiple studies have found an association between vitamin D deficiency and ADHD diagnosis or symptoms in children.
– A meta-analysis of 10 case-control studies found children with ADHD had significantly lower vitamin D levels on average compared to healthy controls.
Vitamin C and Vitamin E
– Evidence linking deficiencies in vitamins C and E to ADHD is more limited. But a few studies have found lower blood levels of these vitamins in children with ADHD compared to controls.
While these observational studies are intriguing, they cannot prove causation. The lower vitamin levels seen in ADHD could be a result of the disorder itself or other confounding factors. However, some interventional trials provide evidence for a causal effect:
Vitamin B6 Supplementation
– Several double-blind placebo-controlled trials have found that high-dose B6 supplements (up to 600 mg/day) significantly reduced ADHD symptoms in children compared to placebo over 6-12 weeks.
– A meta-analysis of 10 randomized controlled trials concluded that B6 supplementation has a modest but beneficial effect on reducing ADHD symptoms.
Folate and B12 Supplementation
– In a randomized trial, children with ADHD received folate, B12 and omega-3 fatty acid supplements or placebo. The vitamin/omega-3 group had significantly greater improvements in ADHD symptoms compared to placebo.
– Another trial found that folate and B12 supplements for 2 months significantly reduced ADHD symptoms compared to placebo in children with hyperhomocysteinemia.
Multivitamin Supplementation
– A few trials have also found multivitamin supplements containing vitamins B6, B9, B12 and C improve ADHD symptoms more than placebo over 2-4 months in children with ADHD.
These intervention trials provide some evidence that correcting vitamin deficiencies may benefit ADHD in some cases. However, not all trials have found positive effects. More research is still needed.
Mechanisms
There are several mechanisms which could help explain why vitamin deficiencies may worsen ADHD for some individuals:
Neurotransmitter Deficits
B vitamins like B6, folate and B12 are required for the production of neurotransmitters including dopamine, serotonin, adrenaline, GABA, and glutamate. Deficiencies in these vitamins could alter neurotransmitter levels in the brain, contributing to problems with attention, behavior, and cognition.
Myelin Impairment
B vitamins are also needed for proper myelin synthesis and maintenance in the brain. Myelin makes up the insulating sheath around nerve fibers and is critical for neurotransmission. Impaired myelination due to vitamin deficiency could affect nerve signaling.
Gene Expression
Folate and vitamin B12 act as methyl donors and are important for epigenetic regulation of gene expression in the brain. Deficiencies could alter expression of genes involved in producing neurotransmitters and other proteins important for brain function.
Oxidative Stress
Antioxidant vitamins like C and E help protect the brain from oxidative damage. Deficiencies may result in higher oxidative stress, which can impair neural signaling and lead to neuroinflammation.
Neuroinflammation
Some vitamins appear to help regulate inflammatory cytokines and processes in the brain. Deficiencies could potentially cause neuroinflammation, contributing to ADHD symptoms through effects on neural transmission, plasticity, and metabolism.
Neurodevelopmental Impairment
Many vitamins play critical roles in brain development and maturation. Deficiencies during pregnancy or childhood could alter normal brain development in ways that predispose to ADHD.
ADHD Diets
Some doctors prescribe special diets and nutrition plans as part of a holistic treatment approach for ADHD. Common recommendations include:
– Eliminating artificial food colors, preservatives and other additives
– Removing sugary and highly processed foods
– Increased intake of foods rich in certain vitamins and minerals
– Taking vitamin/mineral supplements to correct deficiencies
The goal is to reduce dietary factors that may worsen ADHD, while optimizing intake of micronutrients important for brain function.
Some popular ADHD diets include:
Feingold Diet
This diet eliminates artificial colors, flavors, preservatives, and salicylates. Small clinical trials have provided modest evidence that the Feingold diet may reduce hyperactivity in some children.
Elimination Diet
This restrictive diet removes common allergenic foods like dairy, gluten, eggs and soy. Reintroducing foods one at a time can identify triggers. Limited evidence suggests elimination diets may decrease ADHD symptoms in some individuals.
Mediterranean Diet
This diet emphasizes vegetables, fruits, whole grains, legumes, nuts, fish, olive oil, and avoidance of highly processed foods. A few studies suggest the Mediterranean diet may reduce ADHD symptoms more than typical diets.
Supplements
Correcting deficiencies in vitamins like B6, folate, B12, D, zinc, magnesium, and iron through supplements may support ADHD treatment in some cases. But supplements should only be used to treat confirmed deficiencies.
Should Children with ADHD take Vitamin Supplements?
The evidence suggests vitamin deficiencies may potentially contribute to ADHD in a subset of individuals. However, there is no strong evidence to recommend vitamin supplements for all children with ADHD. Here are some key considerations:
– Dietary sources from a balanced diet should provide sufficient vitamin levels for most healthy children. Indiscriminate supplementation is not recommended.
– Testing for vitamin deficiencies is reasonable to identify children who may benefit from targeted supplementation.
– For children with poor dietary intake, a children’s multivitamin containing 100% RDA for B vitamins, vitamin C, D, zinc, magnesium, and iron may be appropriate.
– High dose single vitamin supplements (e.g. high dose vitamin B6 or C) are not recommended outside of short-term targeted use for confirmed deficiencies.
– Supplements are not a substitute for other evidence-based interventions and should be used only as an adjunct to core treatments like behavior therapy, education strategies, and potentially medication.
– Consulting with a doctor knowledgeable in nutrition, dietary changes, and supplements for ADHD is advised when considering vitamin supplements for a child. Self-supplementation without medical guidance is not recommended.
In summary, while vitamin deficiencies could theoretically aggravate ADHD in some cases, universal vitamin supplementation is not warranted for all children with ADHD without confirmed deficiencies. Further research is still needed to determine the effects of vitamin supplementation as a treatment for ADHD. Targeted supplementation based on individual deficiencies may provide some benefit for select patients under medical supervision when used together with standard ADHD interventions.
Conclusion
ADHD is a complex disorder caused by a combination of genetic, biological, and environmental factors affecting brain development and function. While the exact causes are still not fully understood, a growing body of research suggests nutritional factors like vitamin deficiencies may contribute to ADHD in some individuals.
Observational studies show associations between lower blood levels of vitamins like B6, folate, B12, C, D and E in children with ADHD compared to unaffected children. Some interventional trials also report that correcting deficiencies in these vitamins through supplementation may reduce ADHD symptoms in some cases.
Proposed mechanisms include effects of vitamin deficiencies on neurotransmitter production, myelination, gene expression, inflammation, oxidative stress, and neurodevelopment. However, universal vitamin supplementation is not recommended for all children with ADHD without deficiency testing.
Targeted supplementation under medical supervision may provide some benefit when used with standard evidence-based ADHD interventions for select patients with confirmed deficiencies. But more research is still needed to determine the therapeutic effects of vitamin supplements for treating ADHD.