Some studies have shown that omega-3 fatty acids found in fish, nuts, and supplements like fish oil can help lower cholesterol and triglyceride levels. As "good fats," omega-3 fatty acids can also provide other beneficial properties for the heart and even prevent heart disease .
What are omega-3 fatty acids?
Omega-3 fatty acids are types of polyunsaturated fats found in oily fish, plant sources, and some supplements. These fats include:
- Alpha linolenic acid (ALA)
- Docosahexaenoic acid (DHA)
- Eicosapentaenoic acid (EPA)
ALA is available in supplement form and is found in a variety of plant foods, including seeds (especially chia seeds and flax seeds), soybeans, and walnuts.
EPA and DHA are commonly found in the following foods:
- Fatty fish (anchovies, salmon, tuna, halibut, herring, and sardines)
- Walnuts ( walnuts and almonds )
- Supplements (fish oil, cod liver oil, and krill oil; these generally contain different amounts of EPA and DHA)
Omega-3s are called "healthy fats" because they do not appear to contribute to the development of atherosclerosis , which is known to cause heart disease. However, the studies mainly looked at the effects of DHA and EPA on lowering lipids and reducing the risk of cardiovascular disease. ALA is still under study and may be less effective.
Do omega-3s affect lipids?
DHA and EPA were studied primarily by studying the effect of omega-3 fats on lipid levels. Typical doses of EPA and DHA used in these studies ranged from 250 milligrams (mg) to 500-5 grams per day, however there is no RDA for these.
To reach the amount noted by the researchers, you will need to eat a lot of oily fish, nuts, seeds, and other foods that contain these fats. Supplements can be used to increase the amount of omega-3 fats in your diet and help you reach the desired amount. In general, omega-3 fats appear to have a beneficial effect on lipid levels.
Omega-3 fats have a marked effect on triglyceride levels:
- One study found that a daily intake of 900 mg of omega-3 fatty acids resulted in a 4% decrease in triglyceride levels after approximately six months.
- The most effective dose of omega-3 used in most studies was 2 to 4 grams. This led to a drop in triglyceride levels from 25% to 45%.
- The efficacy of omega-3 fatty acid triglycerides appears to be dose dependent. This means that the more omega-3 fatty acids you eat, the lower your triglyceride level.
- Omega-3 fatty acids appear to affect freshly ingested triglycerides and work best when following a healthy diet.
- People with extremely high triglyceride levels (over 500 mg / dL) seem to benefit the most from omega-3 fatty acid supplements.
While foods that contain EPA and DHA can lower triglyceride levels, they can also affect other parts of your lipid profile:
- Omega-3 fats can slightly raise low-density lipoprotein (LDL) cholesterol levels . However, this change is small and ranges from 3% to 10%.
- Omega-3 fats, while increasing LDL, also increase LDL. Smaller LDL particles can increase the risk of atherosclerosis, while larger LDL particles are considered beneficial for heart health.
- Consuming omega-3 fatty acids also appears to slightly increase high-density lipoprotein (HDL) levels .
Not necessarily a panacea
Fish oil may not be a panacea for heart disease, according to a study published in JAMA and recently presented at the 2020 American Heart Association Scientific Sessions . In the study, researchers evaluated omega-3 carboxylic acids or omega-3 CAs (brand name Enova), a drug derived from fish oil .
The STRENGTH study, which began in 2014, included data from 13,078 adults at 675 centers in 22 countries.
All the patients received statins and had known blockages in the arteries of the heart, brain, or legs. They were at increased risk of heart disease due to factors such as smoking and diabetes. Subjects took omega-3 CA medications or a placebo. Corn oil was used as a placebo.
The team compared the rates of cardiovascular death, heart attack, stroke, need for stenting or bypass surgery, and hospitalization for unstable angina in all study participants.
Research has shown that the combination of eicosatetraenoic acid (EPA) and docosahexaenoic acid (DHA), omega-3 fatty acids found in certain types of fish, does not reduce severe heart attacks in high-risk patients.
The researchers found that 1,580 patients experienced at least one cardiac event. There were no significant differences in heart attack risk between participants in one group compared to the other. However, the researchers found that people who took omega-3 fatty acids were more likely to develop atrial fibrillation (an irregular heartbeat) than people who took corn oil.
The trial was stopped in January 2020 after researchers concluded that it likely would not test the benefits of an omega-3 CA drug.
Fish oil research: mixed results
Other studies have also looked at fish oil and cardiovascular health. The evidence was mixed, in part because the researchers used different types and amounts of fish oil and different placebos.
- The 2007 JELIS study also evaluated the use of EPA and statins and found a reduction in nonfatal coronary events. In patients with a history of coronary artery disease, there was a slight decrease in the number of serious coronary events. Placebo was not used .
- The 2019 VITAL study used supplements containing vitamin D3 and omega-3 fatty acids. It showed that fish oil does not reduce the risk of serious heart disease .
- The 2019 REDUCE-IT study evaluated the ethyl of icosapent (trade name Vascepa), a pure EPA in high doses (omega-3 form). The study included people with heart disease or people taking statins with elevated triglycerides. People who took the omega-3 supplement saw 25% lower rates of heart disease and stroke and 20% fewer deaths from heart disease .
Benefits of omega-3 fats for heart health
In addition to positively affecting your lipid profile, omega-3 fats also positively affect other aspects of your heart health:
- Omega-3 fats help maintain a normal heart rate. This is important for patients at risk of heart attack because arrhythmias are the leading cause of cardiac death in the United States.
- Omega-3 fats can improve blood vessel function.
- Omega-3 fats can lower blood pressure and heart rate.
- Omega-3 fats in high doses can reduce inflammation.
- Studies have shown that people with cardiovascular disease who consume fish oil have a reduced risk of sudden death and death from cardiovascular disease .
Omega-3 fatty acids are available in a variety of foods and supplements, including fish oil. Research has shown that DHA and EPA, found in fish oil, may have beneficial effects on several risk factors for cardiovascular disease, although fresh fish is more effective .
Some experts, including the American Heart Association, recommend eating one to two servings of fatty fish per week. One serving consists of 3 1/2 ounces of cooked fish.
If you don't like fish, a fish oil supplement that contains about 1 gram of omega-3 fats may be an alternative. However, you should not increase your dose without consulting your healthcare professional. High doses of omega-3 fatty acids can affect platelet levels in the blood, making a person bleed and bruise more easily.
Prescription and over-the-counter supplements
Prescription omega-3 fatty acids contain a certain amount of natural or modified forms of omega-3 fatty acids. They are purified and completely free of impurities like trans fats, mercury, and other contaminants.
Prescription omega-3 fatty acids are commonly taken by people with very high triglycerides who need high doses of omega-3 fats to lower triglyceride levels.
Over-the-counter (OTC) supplements are classified as "food grade" by the US Food and Drug Administration (FDA). Therefore, they do not need to go through the rigorous purification processes or efficacy studies that prescription drugs must go through.
Get the word of drug information
Evidence shows that the inclusion of omega-3 fatty acids in the diet can have a positive effect on cholesterol levels. The best source is fresh fish and other foods that naturally contain these healthy fats.