The omega-3 fatty acids ALA (alpha-linolenic acid), DHA (docosahexaenoic acid), and EPA (eicosapentaenoic acid) are considered “essential fatty acids” by the global scientific community.† This is for two reasons: (1) they are utilized throughout the body in many biological processes, and (2) your body can’t readily create them on its own. You must get them through your diet.
Omega-3 fatty acids are found throughout the body and are fundamental to its operation. They’re found in the membranes of your cells, the walls of your arteries and blood vessels, and even your eyes. Recent research indicates that omega-3s are also important contributors to brain health as well.
EARLY BRAIN DEVELOPMENT. DHA is especially critical during the period of rapid brain development between conception and a child’s second birthday.
Half of your brain is built from a combination of protein, carbohydrates, salts, and water. Fats account for the other 50% of your brain mass. About 10% to 20% of that fat, or 5% to 10% of the total mass, is DHA. DHA is utilized in the membranes of your brain’s neurons and is involved in the regulation of electrical impulses used to communicate within your brain and nervous system.
From conception to a child’s second birthday, roughly 1,000 days, is the period when a child’s brain experiences the most rapid development. Having a ready supply of DHA is critical during this period. When women are pregnant, the development of the fetal brain requires a continual supply of DHA from the mother, with demand being highest during the last 12 weeks of pregnancy.
The Food and Agriculture Organization (FAO) of the United Nations and the World Health Organization (WHO) recommend that pregnant and lactating women consume 200 mg of DHA per day. After birth, they recommend that infants 0 to 6 months old consume an amount of DHA equivalent to 0.10% to 0.18% of their daily energy input, and from 6 months to 2 years, 10 to 12 mg per kilogram of weight per day.
But the brain doesn’t stop developing after birth, and neither does DHA’s importance to the developing brain. There is some evidence that a mother’s blood levels of DHA during pregnancy impact a child’s cognitive development through the first years of life. More recent studies found that 2 to 6 year old children who had higher levels of omega-3 fatty acids, as well as higher levels of DHA specifically, performed better on evaluations of executive function.
COGNITION. Even into adulthood and old age, supplementation with DHA and EPA omega-3 fatty acids appears to benefit cognitive structure and function.
There is mounting evidence that consuming high levels of omega-3s has a measurable effect on the function and structure of the brain. A study published in Neurology found that middle-aged people with higher blood levels of DHA and EPA performed better on measures of abstract reasoning, and had larger hippocampuses—the region of the brain associated with spatial memory and converting short-term memories to long-term memories.
There is some indication that omega-3 supplementation has a positive impact on memory loss related to aging. For those who are suffering from coronary artery disease (CAD), which impacts blood flow to the brain and accelerates cognitive decline, research suggests that omega-3s can help protect brain function. A 2021 study found that providing high doses of DHA and EPA to people with CAD “had significantly better cognitive function scores for verbal fluency, language, and memory and… visual-motor coordination” over a period of two and a half years.
MENTAL HEALTH. Some studies suggest that omega-3 supplements can reduce the symptoms of depression, but contradicting studies have found otherwise.
Given the role of omega-3s in brain development and structure, it’s unsurprising that researchers have studied whether DHA and EPA have an impact on depression and other mood disorders. The research conducted thus far presents a complicated picture.
One study found that those who took an antidepressant and an omega-3 supplement had “significantly higher improvement in depressive symptoms” than those who only took an antidepressant or omega-3 supplement. On the other hand, a large-scale clinical trial published in JAMA found that a supplement containing DHA and EPA didn’t reduce depression symptoms.
Meanwhile, an analysis of 26 studies presents a more nuanced picture. The analysis found that supplements that were 60% or more EPA delivered measurable improvements in symptoms, while supplements that were 60% or more DHA resulted in no improvements in participants’ depression.
There have been studies conducted on the effectiveness of omega-3s in reducing negative symptoms related to bipolar disorder, but results have been mixed. A study examining the use of omega-3 supplementation to reduce behaviors associated with ADHD showed no evidence of effectiveness, but another study suggested that long-term supplementation could improve ADHD symptoms.
Brain health studies typically utilize high doses of omega-3s, and omega-3s are not recommended as a treatment for any disease or condition.
Research studies on the effects of omega-3 fatty acids on brain health tend to use very high doses of DHA and/or EPA. In the clinical studies and meta-analyses linked in this article where study participants were provided with supplements, the combined daily dosage of DHA and EPA ranged from 500mg to 3,000mg per day, while most supplements have a daily dosage of 300 to 600mg of DHA and EPA.
The high dosages used in studies may be necessary to achieve any potential brain health benefit. In a study examining the relationship between blood levels and brain levels of DHA, daily DHA supplementation of 2,152mg per day increased blood levels by 200% after six months, while levels in cerebrospinal fluid rose by only 28%.
The preliminary nature of much of the research into associations between omega-3s and brain health, as well as the high dosages necessary to increase omega-3 levels in the brain, highlight the necessity of consulting with a health or medical professional before trying an omega-3 supplement for brain health reasons.
While it is recognized that omega-3 fatty acids are essential nutrients and benefit human health, they are not indicated as a treatment for any brain disease or disorder. This article is intended solely as an overview of research on the potential benefits of omega-3s for brain health.
† In the United States, only ALA is considered essential to the diet, even though our bodies do not efficiently synthesize DHA and EPA from ALA.