Did you know that 60% of your brain is fat? Excluding adipose tissue (fat), the brain is the fattiest organ in the human body—and a significant proportion of that fat is omega-3 fatty acids.
The abundance of this fat in the brain underscores the critical link between omega-3s and brain health. From gestation through old age, omega-3s play an essential role in the development, maintenance, and function of your brain.
Omega-3 is a polyunsaturated fatty acid with a molecular structure that makes it fluid, biochemically active, and vital for your health. There are three main types of omega-3s:
- Alpha-linolenic acid (ALA)
- Eicosapentaenoic acid (EPA)
- Docosahexaenoic acid (DHA)
ALA is classified as an essential fatty acid because it is required for good health but cannot be synthesized in the human body. EPA and DHA can be converted in the body from ALA, but the conversion rate is quite low. Therefore, it’s important to get all three omega-3s in food and/or supplements.
Omega-3s have a number of indispensable functions in your body. They are key structural components of cellular membranes as well as potent natural anti-inflammatories. In higher concentrations, they lower triglycerides and are linked with a reduced risk of metabolic syndrome and type 2 diabetes.
Plus, one omega-3—DHA—is absolutely essential for optimal brain health.
How Do DHA Omega-3 Fatty Acids Help the Brain?
DHA is the most abundant omega-3 in the brain and a critical constituent of the membranes that surround neurons (nerve cells), which are involved in everything from sensory input and motor activity to cognition and memory.
DHA is required in numerous brain functions, including:
- Keeping cell membranes fluid, flexible, and functional.
- Serving as a primary component of myelin. Myelin covers and insulates nerve fibers and speeds up the transmission of nerve impulses—which is how neurons communicate with one another and send/receive signals throughout the brain and body.
- Supporting neurogenesis, the growth of new neurons from neural stem cells.
- Boosting neuroplasticity—the ability of the brain to change, adapt, form new connections, and reorganize. This is important not only during brain development but also for lifelong learning, memory, and recovery from brain damage.
- Increasing levels of brain-derived neurotrophic factor (BDNF), which is involved in the growth of neurons, the formation of synapses, neuroplasticity, and brain repair—all of the things that keep your brain functioning as it should.
- Helping curb neuroinflammation (excess inflammation in the brain).
Omega-3 & Brain Function From Gestation Throughout Life
There is no question that DHA is critical during infancy and childhood. Accumulating in the fetal brain during the third trimester of pregnancy and continuing to amass during the first few months of life, DHA is intimately involved in brain growth and development.
The importance of omega-3s for cognitive function persists throughout life. If your brain doesn’t have enough DHA, other fatty acids will be incorporated into cell membranes, making them more rigid and less responsive. Myelin surrounding nerve fibers may be affected, resulting in slower nerve transmission and impaired neurological function.
There could be an increase in neuroinflammation—a feature of serious brain diseases such as Alzheimer's as well as depression and milder memory loss—and a decrease in BDNF and brain repair and plasticity. In fact, a number of studies have shown that a low level of omega-3 and/or consumption of fish is associated with an increased risk of age-related cognitive decline and Alzheimer's disease.
Brain Food: How to Get Your Omega-3s
The best dietary sources of DHA and EPA are oily fish. Algae synthesize DHA and EPA, and fish eat algae and other marine life that consume algae—that’s how these fatty acids accumulate in fish.
Salmon is famous for its omega-3s, but herring, sardines, mackerel, rainbow/steelhead trout, and sea bass are also excellent sources. The best way to feed your brain is to eat these fish at least twice a week. Each 3–4 ounce serving contains around 1,000 mg of DHA plus hefty doses of EPA.
ALA, which is present in walnuts, canola and soybean oil, and is especially concentrated in chia seeds and flax seeds/oil, can be converted into DHA and EPA. But even if you get adequate ALA in your diet, the conversion process is inefficient. British researchers reported that in healthy young women, 9% of dietary ALA was converted to DHA. In healthy young men, the conversion rate was just 0%–4%! If conversion is this poor in healthy young people, it can only be worse in older or ill individuals.
That’s why fish is a superior source of omega-3s. No conversion is necessary. Unfortunately, few Americans eat much fish. Surveys reveal that only 20% of adults and 6% of children and teens eat fish twice a week, and this includes fish low in DHA and EPA. Milk and eggs fortified with omega-3s are an option for picky eaters—DHA levels are low compared to oily fish but may be suitable for kids.
For all these reasons and more, omega-3-rich fish oil, which contains both DHA and EPA, has always been a part of my daily supplement recommendations.
DHA is also available in algae oil and other marine oils such as calamari and krill—all are good sources. Concentrations and proportions of DHA and EPA vary significantly from one source and brand to another, so read labels carefully.
How much omega-3 do you need for brain health? The government’s “adequate intake” (AI) for ALA is 1.1–1.6 g per day for adults. Although there is no specific recommendation for DHA or EPA, here are my suggestions:
- Healthy adults: For overall health maintenance I recommend 350–500 mg of DHA and 500–700 mg of EPA per day. This is the amount found in two capsules of many high-quality fish oil supplements.
- Children: Supplements for infants and young children usually contain 50–100 mg of DHA+EPA per day. As kids get bigger, dose can be gradually increased.
- Pregnancy/lactation: The general recommendation is 200 mg of DHA a day, but some experts suggest doubling or tripling that dose. DHA is abundant in breast milk, but levels depend on the mother’s omega-3 intake. Discuss this with your doctor.
- Memory concerns: Higher DHA doses (900–2,000 mg) have been shown to improve memory and focus in healthy people and those with mild cognitive decline. Although higher omega-3 intake and blood levels have been linked with a reduced risk of Alzheimer's, supplements have not proven effective for treating dementia.
- Depression: Supplemental fish oil has improved symptoms of major depression in multiple studies. Larger doses (1,500–3,500 mg) with higher proportions of EPA provided the greatest benefits.
- ADHD: Several studies have demonstrated the benefits of omega-3 supplements for attention deficit hyperactivity disorder in children. A reasonable dose is 600–1,000 mg of DHA+EPA but check with your pediatrician.
In these doses, omega-3s are safe and well tolerated, but it is always a good idea to consult with your doctor before adding a new supplement to your regimen. Fish oil is better absorbed and tolerated (fewer “fish burps”) if taken with meals containing fat, preferably in divided doses twice a day.