Eating fish twice a week can improve your heart health, according to the American Heart Association. Fish — especially fatty fish, like salmon, tuna and mackerel — are rich in omega-3 fatty acids, a type of essential fat that your body can't create and you must get from your diet. There are two types of omega-3s: DHA and EPA. DHA, or docosahexaenoic acid, plays many crucial roles, including supporting heart and brain health, reducing muscle soreness and reducing the risk of preterm birth.
DHA can improve cardiovascular health, aid ADHD, help prevent preterm births and reduce muscle soreness.
Improves Cardiovascular Health
Both EPA, or eicosapentaenoic acid, and DHA help reduce risk factors for heart disease. According to a 2016 study in the American Journal of Clinical Nutrition, DHA is more effective at modulating risk factors for heart disease, including inflammation and blood lipids. Men and women with excess abdominal fat and mild systemic inflammation who took 3 grams of DHA daily for 10 weeks had a significant decrease in inflammation markers and blood triglycerides compared to those who took EPA.
DHA also increased levels of healthy HDL cholesterol, although it raised the bad LDL cholesterol in men but not women. The study authors concluded that DHA supplementation could have more impact on heart disease than EPA, but more research is needed.
Decreases Symptoms of ADHD
Attention deficit hyperactivity disorder has traditionally been treated with stimulants, but these medications can have severe side effects. Recently, researchers have been investigating the ability to treat the disorder with omega-3 fatty acids with positive preliminary results.
A study published in Neuropsychopharmacology in 2015 found that supplementation with EPA and DHA reduced symptoms of inattention in boys with and without ADHD. Forty boys, ages 8 to 14 years old, randomly received 650 milligrams of both DHA and EPA or a placebo for 16 weeks. The group receiving the supplement had increased blood levels of DHA and reduced ADHD symptoms, while the group receiving the placebo saw no change.
Researchers of a meta-analysis published in Neuropsychiatric Disease and Treatment in 2016 report that DHA supplementation can also help adults with ADHD. In some of the studies selected, ADHD adults had lower serum levels of DHA than adults without ADHD.
Reduces Risk of Preterm Births
Two studies, the Kansas University DHA Outcomes Study and the DHA to Optimize Mother Infant Outcome Study, performed in the United States and Australia, respectively, found a statistically significant reduction in preterm births in mothers who supplemented with 600 to 800 milligrams of DHA a day during pregnancy compared to placebo.
In a 2016 meta-analysis in Prostaglandins, Leukotrienes, and Essential Fatty Acids, researchers examining the study results estimated that DHA supplementation in pregnant women could prevent 1,112 preterm births out of 300,000 births in Australia and 106,030 preterm births in the United States.
Reduces Muscle Soreness After Exercise
Delayed-onset muscle soreness, or DOMS, occurs primarily after eccentric exercise, in which the muscle lengthens rather than contracts. Researchers of a study published in the Journal of Sports Science & Medicine in 2016 hypothesized that DHA supplementation could reduce markers of inflammation after vigorous exercise, thereby reducing DOMS.
Twenty-seven healthy women received 3,000 milligrams of DHA or a placebo for nine days. On the seventh day, the women performed four sets of an eccentric biceps curl exercise at maximum effort. Forty-eight hours after the exercise session, the women supplementing with DHA reported 23 percent less muscle soreness and significantly less muscle stiffness than the control group.