Omega-3 fatty acids (also known as omega-3 fats or n-3 fats) are essential fats that the body cannot produce on its own and must obtain from food.
Foods rich in omega-3 include fish, vegetable oils, nuts (especially walnuts), flaxseeds, flaxseed oil, and leafy green vegetables.
Omega-3 fats are a key family of polyunsaturated fats. There are three main types:
- Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) come primarily from fish and are often called marine omega-3s.
- Alpha-linolenic acid (ALA), the most common omega-3 in Western diets, is found in vegetable oils, walnuts, flaxseeds and flaxseed oil, leafy vegetables, and some animal fats—especially from grass-fed animals.
Recent studies have examined how omega-3 fats influence heart health.
In 2018, researchers found that a high dose of a purified ethyl ester of EPA significantly reduced cardiovascular events in patients at high risk of heart disease.
In a review from Brigham and Women’s Hospital, scientists conducted a systematic review and meta-analysis of 38 trials involving more than 149,000 participants. The analysis included studies of EPA alone as well as combined EPA+DHA therapies.
Overall, omega-3 fatty acids were associated with reduced cardiovascular mortality and improved heart health. Notably, the reduction in heart disease risk was substantially greater in studies using EPA alone compared with combined EPA+DHA supplements, suggesting a particularly strong benefit from EPA.
The researchers emphasized that EPA and DHA have important biological differences. Although both are omega-3 fatty acids, they differ in chemical structure, which affects their stability and how they interact with cholesterol molecules and cell membranes.
The study was published in eClinical Medicine and led by Deepak L. Bhatt and colleagues.
Another study from the Intermountain Healthcare Heart Institute supported these findings. Researchers reported that higher blood levels of EPA alone were associated with a lower risk of heart disease and death, whereas DHA appeared to blunt EPA’s benefits.
The team followed nearly 1,000 patients over 10 years, measuring circulating EPA and DHA levels in blood samples and tracking major adverse cardiac events, including heart attack, stroke, heart failure requiring hospitalization, or death.
Patients with the highest EPA levels had significantly lower risk of major cardiac events. However, higher DHA levels reduced the protective effect of EPA, and individuals with DHA levels exceeding EPA were at increased risk of heart problems.
Based on these findings, the researchers suggested that while omega-3-rich foods remain beneficial, caution may be warranted when recommending omega-3 supplements, particularly combined EPA+DHA formulations.
The study was presented at the 2021 American College of Cardiology Scientific Session and conducted by Viet T. Le and colleagues.
Research from Penn State University has also highlighted the heart benefits of the plant-based omega-3 ALA. For people who do not eat seafood, ALA may help reduce cardiovascular risk.
Analyzing data from multiple studies, the researchers found that higher ALA intake was associated with a 10% lower risk of cardiovascular disease and a 20% lower risk of fatal coronary heart disease. Additional benefits were observed even among people who consumed seafood.
ALA intake was also linked to reductions in atherogenic lipids and lipoproteins—including total cholesterol, LDL cholesterol, and triglycerides—as well as improvements in blood pressure and inflammation, helping explain its cardiovascular benefits.
The findings support dietary guidelines recommending that ALA provide about 0.6%–1% of daily energy intake—approximately 1.1 grams per day for women and 1.6 grams for men. This amount can be achieved through foods such as walnuts, flaxseeds, and cooking oils like canola and soybean oil.
The study was published in Advances in Nutrition and led by Penny Kris-Etherton and colleagues.
Recent research has also explored omega-3 fats and blood pressure. Scientists at the Macau University of Science and Technology found that about 3 grams of omega-3 fatty acids per day—through food or supplements—may be optimal for lowering blood pressure.
Using data from 71 clinical trials involving nearly 5,000 adults, the researchers examined the effects of EPA and DHA intake over an average of 10 weeks.
Participants who consumed 2–3 grams daily of EPA+DHA experienced average reductions of about 2 mmHg in both systolic and diastolic blood pressure compared with those who did not.
People with hypertension benefited the most. In this group, 3 grams daily reduced systolic blood pressure by about 4.5 mmHg, while those with normal blood pressure saw smaller reductions. Increasing intake to 5 grams daily produced modest additional effects in hypertensive individuals.
The National Institutes of Health recommends consuming 1.1–1.6 grams of omega-3 fatty acids daily, while the American Heart Association advises eating two servings of fish (3–4 ounces each) per week as part of a heart-healthy diet.
The research was published in the Journal of the American Heart Association and led by Dr. Xinzhi Li.
Finally, a study from the University of Kansas found that omega-3 supplementation during pregnancy may help protect children from developing high blood pressure.
Researchers studied women with low-risk pregnancies between March 2006 and September 2009. Half received a daily prenatal supplement containing 600 mg of DHA, while the other half received a placebo.
Children of mothers who did not take DHA showed links between overweight or obesity and higher blood pressure. In contrast, children whose mothers received DHA had normal body weight and blood pressure.
The findings suggest prenatal DHA may influence fetal cardiovascular development, potentially protecting against the blood-pressure-raising effects of childhood obesity.
Because DHA is commonly found in prenatal vitamins, fish oil supplements, and fish, obtaining adequate intake is generally feasible. However, researchers noted that many prenatal supplements contain less than the 600 mg dose used in the study.
The study was published in JAMA Network Open and led by John Colombo and colleagues.
