Ingredient guides
Omega-3 Supplements: A Practical Guide to Food, Labels, and Safety
A plain-English guide to omega-3s, when food may be enough, what supplements can and can’t do, and key safety considerations.
What omega-3s are and where they come from
Omega-3 fatty acids are nutrients found in foods and in some dietary supplements. The three main omega-3s are ALA, EPA, and DHA. ALA is found mainly in plant oils such as flaxseed, soybean, and canola oil. EPA and DHA are found in fish and other seafood, and also in supplements such as fish oil, krill oil, cod liver oil, and algal oil.
Your body can convert some ALA into EPA and then DHA, but only in very small amounts. That means getting EPA and DHA from foods, or from supplements if someone chooses to use them, is the more direct way to raise levels of these omega-3s in the body.
What omega-3s do in the body
Omega-3s are important parts of the membranes that surround each cell in the body. DHA is especially concentrated in the retina, brain, and sperm cells. Omega-3s also provide calories and have functions in the heart, blood vessels, lungs, and endocrine system, which is the network of hormone-producing glands.
That broad biology is one reason omega-3s get so much attention. But a nutrient having many roles does not mean every supplement claim about it is equally well supported. The research is stronger for some uses than for others.
When food may be enough
Many people in the United States get enough ALA from food, and they also get small amounts of EPA and DHA. The federal Dietary Guidelines for Americans emphasize getting most nutrients from foods and beverages because foods provide a wider mix of helpful components, not just a single ingredient.
For omega-3s, food sources can fit into an overall healthy eating pattern. Fish and other seafood, especially cold-water fatty fish such as salmon, mackerel, tuna, herring, and sardines, are key sources of EPA and DHA. Plant sources such as flaxseed, chia seeds, walnuts, soybean oil, and canola oil also contribute omega-3s. In some cases, fortified foods can help too.
What the research supports most clearly
The clearest benefits in the supplied research are narrow and specific. For example, getting more EPA and DHA from foods or dietary supplements can lower triglyceride levels. For people with heart disease, the American Heart Association recommends EPA plus DHA, preferably from oily fish, and says supplements are an option under the guidance of a health care provider.
Other uses are more uncertain. Some studies suggest omega-3s from foods may be linked with a lower risk of some chronic diseases, but it is not always clear whether the benefit comes from omega-3s themselves or from the foods that contain them. That makes it hard to generalize from one study or one health goal to another.
What the evidence does not clearly show
The research does not support strong claims for many popular omega-3 uses. For age-related macular degeneration, studies suggest higher omega-3 intake from foods may be linked with lower risk of developing it, but once AMD is present, omega-3 supplements do not keep it from getting worse or slow vision loss.
For dry eye disease, some studies have suggested possible symptom relief from omega-3s, but a large study did not find fish oil supplements worked better than placebo. For rheumatoid arthritis, some trials suggest supplements may help people use less pain-relief medicine when taken with standard treatments, but it is not clear that they reduce joint pain, swelling, or morning stiffness. More research is also needed for Alzheimer’s disease, dementia, cognitive function, ADHD, childhood allergies, and cystic fibrosis. Large studies have not shown an overall cancer risk reduction from omega-3 supplements.
Safety, side effects, and interactions
Omega-3 supplements are usually associated with mild side effects such as unpleasant taste, bad breath, heartburn, nausea, stomach discomfort, diarrhea, headache, and smelly sweat. The U.S. Food and Drug Administration recommends not consuming more than 5 grams per day of EPA and DHA combined from dietary supplements.
Omega-3 supplements may interact with medicines. High doses can increase bleeding risk when taken with warfarin or other anticoagulant medicines. The research also says to talk with a health care provider before using omega-3 supplements if you take medicines, use several supplements at once, or are scheduled for surgery. Supplements are not risk-free just because they are sold over the counter.
How to read omega-3 labels and judge quality
Supplement labels list the active ingredients, the amount per serving, and other ingredients such as fillers, binders, and flavorings. That can help you compare products, but it does not tell you whether a supplement is necessary for you or whether it has been proven effective for your situation.
Independent quality testing seals can show that a product was properly manufactured, contains the ingredients listed on the label, and does not contain harmful levels of contaminants. Even so, these seals do not guarantee that a supplement is safe or effective. Because supplement quality and composition can vary, it is wise to share a complete list of what you take with your doctor, pharmacist, dentist, or dietitian.
Sources
- Dietary supplements: what you need to knowods.od.nih.gov
- Omega-3 fatty acids — consumer fact sheetods.od.nih.gov