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Omega-3 Fatty Acids

Omega-3 fatty acids are key for normal development and growth. Lack of dietary intake of omega-3 fatty acids and too much intake of omega-6 fatty acids is believed to be a significant contributing factor to many diseases. Since the human body cannot make omega-3 fatty acids, we have to get them from our diet. Omega-3 supplements have become one of the most popular supplements in the U.S. They're used to help prevent and treat a number of serious diseases.

Why do people take omega-3 fatty acids?

Studies show strong evidence that omega-3 fatty acids from fish oil can lower blood pressure and triglyceride levels. There's also good evidence that diets high in omega-3 fatty acids help with rheumatoid arthritis as well as osteoarthritis. Past evidence pointed to omega-3 fatty acids reducing risk of heart attacks, strokes, and death from heart disease, but recent research has refuted some of these findings. More specific research is needed to sort this out.

Omega-3 fatty acids have been studied in many other conditions. They include asthma, cancer, depression, psoriasis, and inflammatory bowel diseases such as Crohn's disease and ulcerative colitis. While some of these studies have been promising, they're still inconclusive.

The different types of omega-3 fatty acids can be confusing. There are the fish oils, which contain docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). Then there are the plant sources with alpha-linolenic acid (ALA), which is converted into omega-3 fatty acids in the body.

Studies have generally used fish oils as the source for omega-3 fatty acids. While plant sources with ALA may have the same benefits, less is known about them. For now, fish oils with DHA and EPA have the more established benefit.

How much omega-3 fatty acids should you take?

There are no standard doses for omega-3 fatty acids. The American Heart Association (AHA) recommends 1 gram per day of EPA+DHA for people with heart disease. Higher doses -- between 2 to 4 grams per day -- are used to lower triglycerides. If you need to take omega-3 fatty acid supplements, ask your health care provider what dosage you should use. Children shouldn't use omega-3 fatty acid supplements unless a doctor suggests it. The dose of plant-based fatty acids is generally much higher than for fish oils.

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Can you get omega-3 fatty acids naturally from foods?

Good food sources of omega-3 fatty acids include:

  • Coldwater fish, like mackerel, tuna, salmon, and sardines
  • Cod liver
  • Flaxseed and canola oils
  • Soybeans and tofu
  • Walnuts

The AHA recommends that people eat cold-water fish at least twice a week to increase their intake of omega-3 fatty acids.

Eating fewer foods with omega-6 fatty acids -- like some meats, eggs, and oils -- can also improve the ratio of omega-3 fatty acids in the blood, effectively raising the concentration or levels in the body. Many people in the U.S. eat diets that have 10-25 times as many omega-6 fatty acids as they do omega-3 fatty acids. This imbalance may play a role in the onset of many diseases. The more appropriate ratio appears to be approximately 2:1 or 4:1.

What are the risks of taking omega-3 fatty acids?

  • Side effects. Omega-3 fatty acid supplements might cause upset stomach or diarrhea. These side effects are worse at higher doses.
  • Interactions. If you take blood thinners, anti-platelet drugs, or anti-inflammatory painkillers (like Advil or Motrin), talk to your health care provider about using omega-3 fatty acids. The combination may increase the risk of bleeding. The same risks may apply to people taking supplements like ginkgo biloba.
  • Risks. People who are pregnant, have diabetes, a high risk of bleeding (particularly those on "blood thinners"), or high LDL cholesterol should check with their health care provider before taking omega-3 fatty acid supplements. At very high doses, they could increase the risk of hemorrhagic stroke. Eating fish is generally the best way to get omega-3 fatty acids. But keep in mind that some fish contain higher levels of mercury: king mackerel, swordfish, and albacore tuna. The benefits of eating fish are thought to outweigh the risks, but it's a good idea to limit intake of these high-mercury fish.
WebMD Medical Reference Reviewed by David Kiefer, MD on May 01, 2015

Sources

SOURCES:

American Heart Association: "Fish and Omega-3 Fatty Acids: AHA Recommendation," "Fish Consumption, Fish Oil, Omega-3 Fatty Acids, and Cardiovascular Disease."

Longe, J., ed. The Gale Encyclopedia of Alternative Medicine, second edition, 2004.

Natural Marketing Institute's 2007 Health & Wellness Trends Database.

Natural Standard Patient Monograph: "Omega-3 Fatty Acids."

Office of Dietary Supplements: "Omega-3 Fatty Acids and Health."

Natural Standard: "Omega-3 fatty acids, fish oils and alpha-linolenic acid."

JAMA. 2012; 308:1024-1033.

 

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