Omega-3 fatty acids (also called omega-3 fats and n-3 fats) are essential fats—the body can’t make them from scratch but must get them from food.
Foods high in Omega-3 include fish, vegetable oils, nuts (especially walnuts), flax seeds, flaxseed oil, and leafy vegetables.
Omega-3 fats are a key family of polyunsaturated fats. There are three main omega-3s:
Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) come mainly from fish, so they are sometimes called marine omega-3s.
Alpha-linolenic acid (ALA), the most common omega-3 fatty acid in most Western diets, is found in vegetable oils and nuts (especially walnuts), flax seeds and flaxseed oil, leafy vegetables, and some animal fat, especially in grass-fed animals.
In recent studies, scientists examined how Omega-3 fatty acids affect heart health.
In 2018, a study showed that a high dose of a purified ethyl ester of eicosapentaenoic acid (EPA) in patients at higher heart risk strongly reduced heart disease events.
In one review study from Brigham and Women’s Hospital, researchers found that omega-3 fatty acids can improve heart health.
They did a systematic review and meta-analysis of 38 studies of omega-3 fatty acids, including trials of EPA therapy and EPA+DHA therapy. In total, these trials included more than 149,000 participants.
Overall, omega-3 fatty acids reduced heart disease mortality and improved heart health.
Importantly, they found a much greater reduction in heart disease risk in studies of EPA alone rather than EPA+DHA supplements. The findings support a robust and consistent benefit of EPA.
The researchers note that there are crucial biological differences between EPA and DHA—while both are considered omega-3 fatty acids, they have different chemical properties that influence their stability and strength of the effect that they can have on cholesterol molecules and cell membranes.
The study was published in eClinical Medicine and conducted by Deepak L. Bhatt, et al.
In another study from the Intermountain Healthcare Heart Institute, researchers confirmed that higher EPA blood levels alone lowered the risk of heart disease and death.
However, DHA blunted the heart benefits of EPA. Higher DHA levels at any level of EPA worsened health outcomes.
In the study, the researchers examined nearly 1,000 patients over a 10-year-period. In their blood samples, the circulating levels of EPA and DHA in their blood were measured.
They then tracked major cardiac adverse events, which included heart attack, stroke, and heart failure requiring hospitalization or death.
The team found that patients with the highest levels of EPA had a reduced risk of major heart events. When evaluating how EPA and DHA affect one another, they found that higher DHA blunts the benefit of EPA.
In particular, they also found that those patients with higher levels of DHA than EPA were more at risk for heart problems.
Based on these and other findings, doctors can still tell patients to eat Omega-3-rich foods, but they should not be recommending them in pill form as supplements or even as combined (EPA + DHA) prescription products.
The study was presented at the 2021 American College of Cardiology’s Scientific Session and conducted by Viet T. Le, et al.
Another study from Penn State found that the major plant-based version of omega-3, alpha-linolenic acid (ALA), could benefit heart health and reduce the risk of heart disease for those who don’t eat seafood.
They found that consuming ALA that is found in plant-based foods like walnuts and flaxseeds was linked to a 10% lower risk of cardiovascular disease and a 20% reduced risk of fatal coronary heart disease.
They also found evidence that people who do eat seafood could get extra benefits from eating plant-based omega-3s.
In the study, the team analyzed data from previous studies to evaluate the effects of ALA on heart disease and heart disease risk factors like blood pressure and inflammation.
They found that ALA had beneficial effects on reducing atherogenic lipids and lipoproteins—for example, total cholesterol, low density-lipoprotein cholesterol and triglycerides—as well as blood pressure and inflammation.
This could help explain ALA’s benefits to heart health.
The team was able to find evidence supporting current dietary guidelines that ALA should provide about 0.6%–1% of total energy in a day, which is about 1.1 grams a day for women and 1.6 grams a day for men.
It can be incorporated into the diet with foods such as walnuts, flaxseeds, and cooking oils such as canola and soybean oils.
These recommendations are equal to about 1/2 ounce of walnuts or just under one teaspoon of flaxseed oil.
The researchers said that future studies are needed to help better understand the effects of ALA on other major chronic diseases.
The study was published in Advances in Nutrition and conducted by Penny Kris-Etherton et al.
Recent studies also found that omega-3 fats could help protect blood pressure health.
In a study from the Macau University of Science and Technology, scientists found that roughly 3 grams of omega-3 fatty acids each day, in food or supplement form, maybe the optimal amount needed to help lower blood pressure.
They looked at the link between blood pressure and two omega-3 fatty acids – DHA and EPA.
The researchers used data from 71 clinical trials to examine the link between DHA and EPA and blood pressure in nearly 5,000 adults with and without high blood pressure or cholesterol disorders.
People consumed omega-3 fatty acids through diet and/or prescription supplements for an average of 10 weeks.
The team found people who consumed 2-3 grams daily of a combination of the two omega-3 fatty acids reduced their systolic blood pressure (the top number) and diastolic blood pressure (the bottom number) by an average of 2 mmHg, compared to those who did not consume EPA and DHA.
Those whose blood pressure was high could benefit from consuming higher amounts of omega-3 fatty acids.
For people with high blood pressure, 3 grams of omega-3 fatty acids a day lowered systolic blood pressure by an average of 4.5 mmHg. In those with normal blood pressure, the systolic number fell by 2 mmHg.
When people with high blood pressure consumed 5 grams a day, systolic blood pressure fell by an average of nearly 4 mmHg, while those without hypertension experienced a less than 1 mmHg average decline.
The National Institutes of Health suggests consuming 1.1-1.6 grams of omega-3 fatty acids a day, while the American Heart Association recommends eating two servings of fish (3-4 ounces) a week as part of a heart-healthy diet.
The research was published in the Journal of the American Heart Association and conducted by Dr. Xinzhi Li et al.
Finally, a study from the University of Kansas found that taking an omega-3 supplement during pregnancy may help protect the child from high blood pressure.
They examined women with low-risk pregnancies between March 2006 and September 2009.
Half of the women took a daily prenatal supplement of 600 milligrams DHA and gave half a placebo, not DHA.
The team found that in women who did not take DHA, overweight and obesity linked to higher blood pressure were found in their babies.
However, in the group where mothers got DHA, the babies’ body weight and blood pressure were normal.
The finding suggests pregnant women who take 600 milligrams of DHA can protect their kids from the blood pressure-elevating effects of being overweight in early childhood.
This may be because DHA plays a role in programming cardiac function that preserves normal blood pressure in the case of high postnatal weight gain.
Prenatal DHA intake may help program the developing fetus to be protected against obesity in childhood, which is linked to increased blood pressure.
The researchers suggest that prenatal vitamins, fish oil supplements, and fish meat all contain DHA. Therefore, it is not hard for pregnant women to get nutrients.
It is important for women to take action prior to the birth of their kids to optimize their health.
But they warn that although many prenatal supplements in the US contain DHA, most have much less than 600 milligrams.
The research was published in JAMA Network Open and conducted by John Colombo et al.
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