Omega-3 fatty acids are fats your body cannot make in large amounts, so they must come from food or supplements. The three main types are ALA, EPA and DHA. This guide explains where omega-3s come from, how much is advised, what the research says about heart health and pregnancy, and how to use supplements safely, based on the NIH Office of Dietary Supplements consumer fact sheet.
The Three Types: ALA, EPA and DHA
ALA is found mainly in plant foods. EPA and DHA are found in fish and seafood. The NIH says recommended amounts have been set only for ALA, and that recommended amounts of EPA and DHA have not been established.
How Much ALA Do You Need?
The NIH lists these adequate daily intakes of ALA:
- Children 1 to 3 years: 0.7 g; 4 to 8 years: 0.9 g
- Teen boys 14 to 18 years: 1.6 g; teen girls 14 to 18 years: 1.1 g
- Adult men: 1.6 g; adult women: 1.1 g
- Pregnant women: 1.4 g; breastfeeding women: 1.3 g
Most people in the United States get enough ALA, and true deficiency, which can cause rough, scaly skin and an itchy rash, is very rare.
Best Food Sources of Omega-3
- Fatty fish such as salmon, mackerel, tuna, herring and sardines
- Flaxseed, chia seeds and walnuts
- Flaxseed, soybean and canola oils
- Fortified eggs, yogurt, juices, milk and soy drinks
Omega-3 and Heart Health
The NIH explains that getting more EPA and DHA from foods or supplements lowers triglyceride levels. The American Heart Association recommends one to two servings of seafood per week. For people who already have heart disease, it suggests about 1 g a day of EPA plus DHA, preferably from oily fish, with supplements as an option under a healthcare provider guidance. It does not recommend omega-3 supplements for people who are not at high risk of cardiovascular disease.
Omega-3 in Pregnancy and Breastfeeding
Eating 8 to 12 ounces of fish and other seafood per week may improve your baby health. Choose fish with higher EPA and DHA and lower mercury, such as salmon, herring, sardines and trout. The NIH says it is not clear whether supplements help, though some studies show they may slightly increase birth weight and the length of pregnancy.
What About Other Health Claims?
- Cancer: a large trial found omega-3 supplements did not reduce overall cancer risk.
- Dry eye: a daily dose of 2,000 mg EPA plus 1,000 mg DHA for one year did not improve more than placebo.
- Age-related macular degeneration: supplements do not slow progression once it is present.
- Rheumatoid arthritis: omega-3s may reduce the need for pain-relief medicine, but it is unclear if joint pain or stiffness improves.
Research on ADHD, childhood allergies and brain function is still ongoing.
Safety, Upper Limit and Interactions
The FDA recommends no more than 5 g a day of EPA and DHA combined from supplements. Side effects are usually mild and can include an unpleasant taste, bad breath, heartburn, nausea, stomach discomfort, diarrhea, headache and smelly sweat. High doses may cause bleeding problems when taken with warfarin or other anticoagulants, so talk to your doctor first if you take blood thinners.
When to See a Doctor
- You have heart disease, high triglycerides or take blood thinners
- You are pregnant or planning pregnancy and want to take a supplement
- You have ongoing skin rash or dryness with no clear cause
Frequently Asked Questions
What foods are rich in omega-3?
Fatty fish such as salmon, mackerel, tuna, herring and sardines are rich in EPA and DHA. Flaxseed, chia seeds, walnuts and some oils provide ALA.
How much omega-3 do I need per day?
The NIH sets adequate intakes only for ALA: 1.6 g for men and 1.1 g for women. No recommended amounts exist for EPA and DHA.
Are omega-3 supplements good for the heart?
EPA and DHA lower triglycerides, but the American Heart Association does not recommend supplements for people without high cardiovascular risk. Ask your doctor.
What is the maximum safe dose of omega-3?
The FDA recommends no more than 5 g a day of EPA and DHA combined from supplements.
Can omega-3 interact with blood thinners?
Yes. High doses may cause bleeding problems with warfarin or other anticoagulants, so check with your doctor.
Related reading: Vitamin D daily needs and sources | Vitamin B12 deficiency guide | Vitamin A daily needs
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Medical disclaimer: this article is for general information and does not replace advice from a qualified doctor. Do not start, stop or change any supplement or medicine without medical advice.