The Health Benefits of DHA

Docosahexaenoic acid (DHA) is an omega-3 fatty acid essential for brain development during pregnancy and early childhood. It is also linked to improved heart health, better vision, and reduced inflammatory response. This long-chain fatty acid is found in cell membranes throughout the body and helps to transmit messages between nerves.

DHA is naturally produced in small quantities by our bodies, but to achieve adequate amounts, DHA needs to be taken in through dietary sources such as cold-water fish, grass-fed meat, dairy products, or omega-3 enriched or pasture-raised eggs. It is also available as a supplement, such as fish oil.

Health Benefits

The brain is a fatty organ, and between 10% and 20% of its total fats are DHA. Of the polyunsaturated fatty acids in the brain, 90% are DHA, which is especially concentrated in the brain's gray matter. But research shows that DHA has anti-inflammatory properties and heart health benefits as well.

Supports Fetal Development

During pregnancy, people may be advised to take prenatal supplements containing 200mg to 300mg of DHA due to its benefits on brain development. Several studies have found positive associations between DHA supplementation during pregnancy and neurological development in infants.

• Autism and ADHD: Research published in the journal Critical Reviews in Food Science and Nutrition in 2019 shows that higher DHA levels at birth are associated with better childhood neurodevelopmental health, while lower DHA levels were linked to higher rates of autism spectrum disorders and attention-deficit/hyperactivity disorder.
• Brain development: An older study showed that children of mothers who supplemented during pregnancy demonstrated better problem-solving abilities during the first year of their life than control subjects. More recent research showed a link between mothers' DHA status and kids' performance on language and short-term memory tasks at ages 5 and 6.
• Eye health: A study published in 2008 found babies of mothers who supplemented with DHA had better early visual acuity than those whose mothers did not supplement. Research published in 2014 supports this finding.

Improves Pregnancy Outcomes

Supplementation with DHA during the later weeks of pregnancy is also linked to a decreased risk of early preterm labor. In addition, supplemented pregnancies had lower rates of infants born at 34 weeks or earlier and shorter hospital stays for infants born preterm.

In the study, published in the American Journal of Clinical Nutrition, 350 people were given either 600mg of DHA or a placebo daily during the last half of pregnancy. Those taking the DHA had a longer duration of pregnancy and babies with greater birth weights, lengths, and head circumference than those given a placebo.

Essential for Brain and Nervous System Development

In the first 6 months of life, DHA is especially important for the development of the nervous system. Breastfeeding parents are encouraged to continue taking 200mg to 300mg of DHA a day, and most infant formulas also contain DHA. 

Low levels of DHA in early childhood are associated with lower literacy ability, while higher levels are linked to enhanced cognitive development and performance, memory, and speed of performing mental tasks, according to a 2014 study published in the journal Nutrients.

May Alleviate Symptoms of ADHD

Although study results are mixed, some have shown that supplementing with DHA may help to ease the symptoms of ADHD. An article published in 2017 reviewed 16 studies looking at omega-3/6 supplementation and found in 13 studies that supplementation demonstrated favorable effects on ADHD symptoms.

A small study published in European Child and Adolescent Psychiatry in 2019 found 6 months of supplementation with DHA had positive effects on behavioral and cognitive difficulties. Those who took DHA supplements had small improvements in psychosocial functioning, emotional problems, and focused attention. 

May Support Brain Health

DHA may help protect against age-related cognitive decline, suggests a 2010 research review from Current Alzheimer's Research. Analyzing data from previously published clinical trials, the authors found that taking 900mg supplements containing both DHA and EPA (eicosapentaenoic acid), another omega-3 fatty acid found in fish oil, may help treat mild cognitive impairment, but not Alzheimer's disease.

A 2013 study found similarly promising results, but had a small pool of subjects. A retrospective study with more participants (about 800) also showed an association between supplementing with fish oil and reduced cognitive decline—but not in patients who already had Alzheimer's disease.

 May Protect Against Depression

A 2019 review of 26 studies on polyunsaturated fatty acid levels and supplementation in people with depression "showed an overall beneficial effect of omega-3 polyunsaturated fatty acids on depression symptoms." More research is necessary to understand how DHA and EPA work, together and separately, in managing depression.

May Reduce Risk of Heart Disease

While there was hope for many years that DHA supplementation might improve outcomes in people with heart disease, more recent evaluation has not been able to demonstrate a mortality benefit. However, a 2019 study showed a link between low levels of DHA and EPA and increased incidence of heart attack, stroke, and cardiovascular disease.

May Reduce Inflammation

Lab, animal, and human studies all suggest that DHA plays a role in helping the body mount a response to inflammation. For example, a 2013 review of research concluded that DHA could be a "key tool" in preventing metabolic syndrome, which is associated with inflammation. Metabolic syndrome can lead to type 2 diabetes, heart disease, and stroke.

Possible Side Effects

Although DHA is generally considered safe, taking DHA in the form of fish oil is known to cause a number of side effects, including bad breath, heartburn, and nausea.

What's more, there's some concern that fish oil might reduce immune system activity and weaken the body's defense against infection. In addition, taking fish oil in combination with certain medications (such as blood pressure drugs) may produce harmful effects in some cases. It's important to consult your physician before combining fish oil with medications.

Fish oil has a blood-thinning effect and should be taken with caution and only after consulting with a physician by people who are on blood thinners or anti-platelet medications.

Dosage and Preparation

DHA is sold as a gel cap supplement, a gummy chewable, or a liquid. Many dietary supplements contain a combination of DHA and EPA. A typical fish oil supplement provides about 1g fish oil, containing 180mg EPA and 120mg DHA, but check labels because doses can vary.

Most studies use larger amounts of DHA (1,000mg to 2,500mg). If you prefer to avoid fish, you can purchase a DHA supplement made from algae.

Consuming two to three servings of fatty fish, such as salmon, tuna, sardines, mackerel, and herring, per week will provide about 1,250mg EPA and DHA per day. However, people who are pregnant and young children should avoid tuna and other fish that is high in mercury, including shark, tilefish, swordfish, and king mackerel. There is also a small amount of DHA (0.03g per serving) in eggs.

What to Look For

Widely available for purchase online, DHA supplements are sold in many drugstores, grocery stores, natural-food stores, and stores specializing in dietary supplements. Supplements are not regulated by the FDA. To ensure you are getting a quality brand, look for an independent third-party seal, such as U.S. Pharmacopeia, NSF International, or ConsumerLab.

While taking DHA supplements may offer certain health benefits, it's too soon to recommend DHA as a treatment for any condition. It's important to note that DHA supplements should not be used as a replacement for the standard care of a chronic condition. Avoiding or delaying treatment for a chronic condition in favor of self-treating with DHA may have serious health consequences.