Omega-3 fatty acids

What it is

• Most research has focused on two omega-3s called EPA and DHA.
• EPA and DHA are found in seafood, especially cold-water fish such as salmon, mackerel, and tuna, and in fish oil supplements.
• A third type, ALA, is found in certain plant oils such as flaxseed, soybean, and canola oils.
• Omega-3 supplements include fish oil, krill oil, cod liver oil, and algal oil, which is a vegetarian source from algae.

Sources: NCCIH (NIH): Omega-3 Supplements: What You Need To Know ↗ · NIH Office of Dietary Supplements: Omega-3 Fatty Acids - Consumer ↗

How it's thought to work

• Omega-3s are important parts of the membranes around each cell in the body.
• DHA levels are especially high in the eye's retina, the brain, and sperm cells.
• Omega-3s also give the body calories for energy and have many functions in the heart, blood vessels, lungs, and immune system.

Source: NIH Office of Dietary Supplements: Omega-3 Fatty Acids - Consumer ↗

What the research has found so far

• A 2020 review of 23 studies found that EPA and DHA reduce triglycerides, a type of blood fat, by about 15 percent.
• A 2020 review of 86 studies found that increasing EPA and DHA slightly reduced the risk of coronary events and coronary death.
• A large trial found omega-3 supplements did not reduce the overall risk of cancer or of breast, prostate, or colorectal cancers.
• Once someone has age-related macular degeneration, omega-3 supplements do not keep the disease from getting worse.

Sources: NCCIH (NIH): Omega-3 Supplements: What You Need To Know ↗ · NIH Office of Dietary Supplements: Omega-3 Fatty Acids - Consumer ↗

On Omega-3 fatty acids and aging, PubMed lists 142 trials in people, 192 studies that watched people over time, 658 animal and lab studies. See the counts and searches

Side effects and risks

• The pages say side effects are usually mild, such as unpleasant taste, bad breath, heartburn, nausea, and diarrhea.
• Side effects are usually mild and include unpleasant taste, bad breath, heartburn, nausea, stomach discomfort, diarrhea, headache, and smelly sweat.
• Methyl mercury in seafood can be harmful to the brain and nervous system if a person is exposed to too much.

Sources: NIH Office of Dietary Supplements: Omega-3 Fatty Acids - Consumer ↗ · NCCIH (NIH): Omega-3 Supplements: What You Need To Know ↗

Who should be careful, and drug interactions

High doses of omega-3s may cause bleeding problems when taken with warfarin or other blood-thinning medicines.

Source: NIH Office of Dietary Supplements: Omega-3 Fatty Acids - Consumer ↗

Approval and legal status

Prescription omega-3 products differ from typical supplements, so their effects may not be the same.

Source: NCCIH (NIH): Omega-3 Supplements: What You Need To Know ↗

Amounts used in studies

What studies or labels describe, not a recommendation.

The FDA recommends no more than 5 g per day of EPA and DHA combined from supplements. A typical fish oil supplement provides about 1,000 mg of fish oil, with 180 mg EPA and 120 mg DHA, but doses vary widely.

Sources: NIH Office of Dietary Supplements: Omega-3 Fatty Acids - Consumer ↗ · NIH Office of Dietary Supplements: Omega-3 Fatty Acids - Health Professional Fact Sheet ↗

Roughly what it costs

The 4 products we list that contain Omega-3 fatty acids cost from $18.74 to $59.95, as read from the makers' pages. See the products

Questions to ask your doctor

• Is Omega-3 fatty acids a sensible option for me, given my health and the medicines I take?
• Could Omega-3 fatty acids interact with any medicine or supplement I already take?
• What side effects should I watch for, and when should I stop or call you?
• Supplements aren't checked by the FDA before sale. Is there a brand or a third-party test seal you would trust?
• How would we tell whether it is helping, and when should we review it?