The human body can make most of the fats it needs except for omega-3 fatty acids. These fats are considered "essential" because we have to acquire them from our diet. Omega-3 fats are present in cell membranes throughout the body and are involved in proper cell function, regulating inflammation and blood clotting, and helping blood vessels constrict and relax.
Over 2/3 of U.S. adults don't consume enough omega-3s despite fish oil supplements being the most commonly taken natural supplement.
Keep reading to learn about omega-3s, their possible health benefits, recommended daily intakes, balancing omega-3 and omega-6 intake, and how to acquire omega-3s through diet and supplementation.
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What Is Omega-3?
Omega-3 fatty acids have at least one double bond in their structure, which is why we call them "unsaturated fatty acids." There are several different omega-3s, but this article will focus on alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), the docosahexaenoic acid (DHA) as they are most relevant to human health. ALA is found mainly in plant foods. EPA and DHA are abundant in fish and other seafood because fish eat algae that originally synthesized the EPA and DHA.
ALA is an essential fatty acid, meaning the body can't produce it; we must acquire it through our diet. Some ALA is converted in the body to EPA and then to DHA. This conversion process varies between people and can be inefficient, so obtaining pre-formed EPA and DHA directly from food and supplements is the most reliable way to increase the levels of these omega-3 fatty acids in the body.
What Are Some Omega-3 Health Benefits?
Omega-3s are best known for their effects on the cardiovascular system. Research is ongoing to continue investigating cardiovascular benefits and other possible health benefits.
Cardiovascular System
Omega-3 fatty acids have many potential benefits for cardiovascular health. They can lower cardiovascular disease risk by raising good HDL cholesterol and lowering blood pressure.
Another benefit of Omega-3 fatty acids is the treatment of elevated triglycerides. High triglycerides in the blood, called hypertriglyceridemia, increase the risk of atherosclerosis and, consequently, the risk of heart disease and stroke. In 2019, the U.S. FDA approved an omega-3 fatty acid called icosapent ethyl to reduce the risk of cardiovascular events in adults with elevated triglyceride levels.
Omega-3 fatty acids may lower the risk of blood clots.
Inflammatory Arthritis
Omega-3 fatty acids also have a role in reducing inflammation in rheumatoid arthritis. Studies have shown that omega-3 fatty acids may modulate disease activity by reducing the severity of pain and the number of swollen and tender joints.
Dementia and Cognitive Function
Research into omega-3 intake and cognitive function is ongoing. A recent meta-analysis found that supplementing with omega-3 was neither helpful nor harmful in treating people with mild-to-moderate Alzheimer's disease.
Cell Membrane Structure
Omega-3 fatty acids are essential components of cell membranes. DHA levels are particularly high in the retina, brain, and sperm cells.
How Much Omega-3 Should We be Consuming Per Day?
The dosage can vary. However, below are some evidence-based recommendations to get you started:
ALA
Daily recommended intakes for ALA (the precursor to both EPA and DHA) are as follows:
- Adult males: 1.6 g
- Adult females: 1.1 g
- Pregnant females: 1.4 g
- Breastfeeding females: 1.3 g
Although ALA is essential and gets converted to the long-chain fatty acids DHA and EPA, this conversion is not always very efficient. Much of the ALA we consume provides energy for our bodies instead. To achieve optimal levels of DHA and EPA, it is usually necessary to consume them directly by eating fish or taking supplements like fish or algae oil.
DHA/EPA
There are no official guidelines on the recommended daily intake for DHA and EPA, but recommendations for most adults range between 250 to 500 milligrams per day. However, different medical associations have come up with their own recommendations for treating various conditions.
For instance, the American Heart Association (AHA) recommends eating fish at least twice weekly.
Also, according to the AHA, 2-3 grams per day of DHA and EPA can effectively lower blood pressure.
Up to 4 grams per day of DHA and EPA might be needed to lower triglycerides.
A study looking at the treatment of rheumatoid arthritis found that 2.7 grams per day of EPA plus 1.8 grams per day of DHA effectively reduced symptoms.
Considerations for Pregnant or Breastfeeding Women
The 2015–2020 Dietary Guidelines for Americans state that pregnant women should consume 8–12 ounces of seafood per week, choosing options higher in EPA and DHA and lower in methylmercury, such as salmon, sardines, herring, and trout.
The American Academy of Pediatrics recommends 200–300 mg DHA daily for breastfeeding women. Women can achieve this by eating one to two servings of fish per week.
What Should The Omega-3 to Omega-6 Ratio Be?
Omega-6 fatty acids are a family of fats found in plant oils and seeds. They are different from omega-3 fatty acids. Too many omega-6 fatty acids can alter cell function and harm heart and blood vessel cells. The balance between omega-6 and omega-3 fatty acids is an important determinant for brain development and also in decreasing the risk for coronary heart disease, hypertension, cancer, diabetes, arthritis, and other autoimmune and possibly neurodegenerative disorders.
Our Western diet typically has a very unfavorable ratio of around 15:1 omega-6:omega-3. Excessive amounts of omega-6 fatty acids and a very high omega-6:omega-3 ratio may promote the pathogenesis of many diseases.
Studies have shown that a ratio of 4:1 omega-6:omega-3, or less, is beneficial for cardiovascular health and reduces the risk of certain types of cancer.
A ratio of 2-3:1 omega-6:omega-3 suppressed inflammation in patients with rheumatoid arthritis.
A low omega-6:omega-3 ratio in women with breast cancer was associated with decreased risk.
There are blood tests to determine your omega-3 and omega-6 levels and your omega-6:omega-3 ratio. This information and your medical history can be important for you and your healthcare provider to individualize omega-3 supplementation and dietary modifications, if required.
What Foods Have Omega-3?
The following table presents the amounts of omega-3 fatty acids in grams per serving.
Individuals should consider that some fish have higher levels of mercury than others. These include:
- king mackerel
- marlin
- shark
- swordfish
- tilefish
- tuna
- perch
- largemouth bass
- striped bass
- pikeminnow
- white sturgeon
- blackfish
- catfish
- black crappie
Too much mercury can cause mercury poisoning, damaging the brain, nervous system, and other body systems. Pregnant women and children aged 11 or younger should not eat these fish.
Lower mercury fish are anchovy, herring, mackerel, salmon, sardine, trout, whitefish, and light, canned tuna.
What Supplements Have Omega-3?
Several types of dietary supplements contain omega-3s.
- Fish oil supplements contain EPA and DHA.
- Fish liver oil supplements contain EPA, DHA, and vitamins A and D.
- Flaxseed oil contains ALA.
- Krill oil contains EPA and DHA.
- Algal oils are a vegetarian source of DHA; some also include EPA.
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Summary
Omega-3 polyunsaturated fatty acids are essential for cell membrane structure and function. Scientific evidence shows that they have anti-inflammatory properties and may lower triglycerides, blood pressure, and the risk for cardiovascular disease.
A healthy diet, including seafood, in recommended amounts and within calorie limits, supports health and helps minimize the risk of diet-related chronic diseases, such as type 2 diabetes, cardiovascular disease, and obesity.
Women who might become or are pregnant or breastfeeding should consume at least eight and up to 12 ounces of a variety of seafood per week but from options that are lower in methylmercury. Notably, pregnant or breastfeeding women and young children should not eat certain fish high in methylmercury.
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