Benefits, Risks, Deficiency, Sources, and More

Docosahexaenoic acid (DHA) is an omega-3 fatty acid primarily found in cold-water fish and exists alongside eicosapentaenoic acid (EPA), another fatty acid. As one of the most important forms of omega-3s, DHA is responsible for brain growth and function. In the body, DHA levels are particularly high in the retina (eye), brain, and sperm cells. In the gray matter of the brain, DHA represents up to 20% of its total lipids (fats).

Your body needs DHA through every stage of your life. It’s involved in healthy development in the womb and the prevention of preterm birth as well as the prevention of heart disease and improvements in eye health and cognitive function as you age.

In general, DHA is safe and can be found in fish and supplements. However, taking high amounts of DHA or eating excessive amounts of fish could lead to health risks. For instance, high levels of DHA could increase the risk of bleeding. It’s also possible that DHA may interfere with some medications like those used to treat type 2 diabetes.

Dietary fats like omega-3 fatty acids are an important part of a balanced and nutritious diet. Along with adding interesting flavor to your food, these fats provide vital health benefits like the reduction of heart disease. Omega-3s also are being researched for their use in preventing certain types of cancers, neurological disorders, and arthritis. DHA, in particular, may benefit your health in several ways.

May Reduce Triglycerides

Several studies show that taking DHA alone or with EPA can reduce your triglyceride levels. Research has found taking 1.25-4 grams (g) daily for up to seven weeks can reduce triglyceride levels by 17-24% in adults with mildly high lipid levels, imbalanced lipid levels, or high triglyceride levels.

Another study found that taking fish oil enriched with 810 milligrams (mg) of DHA and 210 mg of EPA daily for eight weeks reduced triglyceride levels by 23% in premenopausal adults. It’s important to note that DHA does not lower total cholesterol and it may increase LDL cholesterol (bad cholesterol) levels.

May Prevent Preterm Birth

Research indicates that taking DHA during pregnancy may reduce the likelihood of preterm delivery, especially in people who have low DHA levels at the beginning of their pregnancy. A large clinical trial found that taking 1,000 mg a day of DHA starting at around 12-20 weeks resulted in a preterm birth rate of 1.7% compared to 2.4% in pregnant people only taking 200 mg of DHA a day.

However, taking fish oil supplements when you already have good DHA levels may increase the risk of preterm delivery. One study found that taking a fish oil supplement with 800 mg of DHA daily from before 20 weeks gestation until 34 weeks gestation showed an increased risk of preterm birth when the person’s baseline omega-3 status was more than 4.9%, compared to a placebo. However, this risk is reduced from 3.2% to 0.7% in people with an omega-3 level below 4.1%.

May Reduce the Risk of Heart Disease

There also is some evidence that increasing the amount of DHA in your diet either through food or supplementation may reduce your risk of heart disease. One study found that increasing the amount of DHA a person consumes through supplementation reduced their risk of heart-related issues.

Other evidence suggests that DHA may be associated with a low risk for total mortality, sudden cardiac arrest, and fatal and non-fatal myocardial infarctions. However, researchers note that more research is needed to fully understand the role of DHA in promoting heart health.

Although specific recommended amounts of DHA have not been established, medical experts do recommend that you consistently get omega-3 fatty acids, which contain DHA, from food or supplements.

There is also not an established tolerable upper intake level. However, the U.S. Food and Drug Administration (FDA) has stated up to 3 g per day of DHA is generally recognized as safe for most people.

For people who are pregnant or breastfeeding, most experts recommend getting about 200-300 mg of DHA daily, primarily from food. You can typically get this amount by eating 8-12 ounces (oz) of seafood a week during pregnancy and 4-8 oz a week while breastfeeding.

People following a vegan diet can meet their DHA needs with supplements—though it’s important to work with a healthcare provider on how much to take during pregnancy.

Most forms of fish, fish oils, cod liver oils, algal oils, and krill oils contain DHA. You also may find it added to certain brands of eggs, milk, yogurt, juice, and soy drinks. Breast milk and infant formula can also contain DHA. Most brands of formula have been adding DHA to their infant formulas in the United States since 2002.

Foods with the highest amount of DHA include:

• Salmon: 1.24 g
• Herring: 0.94 g
• Sardines: 0.74 g
• Canned salmon: 0.63 g
• Mackerel: 0.59 g
• Sea bass: 0.47 g
• Rainbow trout: 0.44 g
• Oysters: 0.23 g
• Canned tuna: 0.17 g
• Shrimp: 0.12 g

Eggs and chicken breast also contain very small amounts of DHA.

Supplements

If you are looking for a supplement, most omega-3 supplements contain DHA. For instance, a typical fish oil supplement contains about 1,000 mg of fish oil and about 120 mg of DHA.

Plant-based sources of omega-3s like algal oil usually contain around 100-300 mg of DHA. Researchers have shown the bioavailability of DHA from algal oil is equivalent to that of cooked salmon.

However, different forms of omega-3 supplements can vary in quality, ingredients, and amounts. Check product labels to ensure you are getting the types and amounts of omega-3s that you want. Also, when buying any supplement make sure it is third-party tested for purity and potency since supplements are not regulated by the FDA.

DHA is generally considered safe. However, taking large amounts of omega-3 fatty acids such as DHA might increase the risk of bleeding. DHA also can increase blood glucose levels, which could make the management of type 2 diabetes more difficult.

For these reasons, the FDA recommends limiting the amount of DHA you consume each day to 3 g from food. If you are taking a supplement, you should consume no more than 2 grams of DHA from food per day.

Side effects from taking omega-3 supplements are usually mild—unless you take too much. Typical side effects from normal supplementation can include a bad aftertaste, bad breath, smelly sweat, heartburn, stomach discomfort, nausea, diarrhea, and headache.

Interactions

If you are taking medications, it’s important to talk to your healthcare provider before supplementing with DHA as it could interact with your existing medications or supplements. For instance, when taken alongside drugs for high blood pressure, DHA could increase the risk of hypotension (or low blood pressure).

DHA also might interfere with the effectiveness of diabetes medications and could increase the risk of bleeding when combined with anticoagulant or antiplatelet drugs (blood thinners).

DHA (docosahexaenoic acid) is an important omega-3 fatty acid that contributes to several important functions in the body such as brain development in fetuses and brain function in adults and children. Most people get enough DHA through their diet, though some people choose to use supplements for the added health benefits.

There is evidence that DHA may reduce triglyceride levels, protect heart health, and prevent preterm labor. If you are concerned about your DHA levels, especially if you do not eat fish, talk to a healthcare provider about supplementation. However, supplementation may not be right for everyone.