Flaxseed oil comes from the seeds of the flax plant (Linum usitatissimum, L.). Flaxseed oil contains both omega-3 and omega-6 fatty acids, which are needed for health. Flaxseed oil contains the essential fatty acid alpha-linolenic acid (ALA), which the body converts into eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), which is the omega-3 fatty acids found in fish oil. Some researchers think flaxseed oil might have some of the same benefits as fish oil. But the body is not very efficient at converting ALA into EPA and DHA. The benefits of ALA, EPA, and DHA are not necessarily the same. Omega-3 fatty acids, usually from fish oil, have been shown to reduce inflammation and help prevent certain chronic diseases, such as heart disease and arthritis. Studies are mixed about whether flaxseed oil is useful for the same conditions.
Getting a good balance of omega-3 and omega-6 fatty acids in the diet is important. These essential fats are both examples of polyunsaturated fatty acids, or PUFAs. Omega-3 fatty acids help reduce inflammation, while many omega-6 fatty acids tend to contribute to inflammation. A healthy diet should consist of roughly 2 to 4 times fewer omega-6 fatty acids than omega-3 fatty acids. However, the typical American diet tends to contain 14 to 25 times more omega-6 fatty acids than omega-3 fatty acids. Many researchers believe this is a significant factor in the rising rate of inflammatory disorders in the United States.
Flaxseed (but not flaxseed oil) also contains a group of chemicals called lignans that may play a role in cancer prevention. In fact, flaxseed is the richest vegetable source of lignans.
Clinical studies suggest that flaxseed oil and other omega-3 fatty acids may help treat a variety of conditions.
People who follow a Mediterranean diet tend to have an increased HDL (good) cholesterol level. The Mediterranean diet emphasizes fish and healthy fats, such as olive oil, and has a healthy balance between omega-3 and omega-6 fatty acids. Whole grains, root and green vegetables, daily portions of fruit, fish and poultry, olive and canola oils, and ALA (from flaxseed, flaxseed oil, and walnuts) are also part of the Mediterranean diet. Red meat and saturated fats are not part of the diet.
However, whether taking supplements of flaxseed or flaxseed oil helps lower cholesterol is up for debate. Some small studies show it has beneficial effects on cholesterol levels, but one double blind study found no evidence that it lowered cholesterol.
Eating a diet rich in fruits, vegetables, whole grains, nuts or legumes, and ALA-rich foods may substantially reduce the recurrence of heart disease. One of the best ways to help prevent and treat heart disease is to eat a diet low in saturated and trans fat and rich in monounsaturated and polyunsaturated fats (including omega-3 fatty acids from flaxseed and fish). Evidence suggests that people who eat an ALA-rich diet are less likely to suffer a fatal heart attack. ALA may reduce heart disease risk through a variety of ways, including making platelets less "sticky", reducing inflammation, promoting blood vessel health, and reducing risk of arrhythmia (irregular heart beat).
Several human studies also suggest that diets rich in omega-3 fatty acids, including ALA, may lower blood pressure.
However, it is not clear whether taking flaxseed oil as a supplement would have the same effect on heart health.
Preliminary evidence suggests that taking 1 to 2 g of flaxseed per day can improve the symptoms of dry eye in people with Sjogren's syndrome. Sjogren's syndrome is an autoimmune condition where the immune system attacks glands in the body that produce moisture like salivary and tear glands.
Studies suggest that flaxseed oil may help prevent the growth of breast tumors. In one Canadian Study, researchers discovered that flaxseed oil prevented breast tumor growth, likely through ALA content. People with breast cancer should not take any nutritional supplement without their doctor's approval.
Studies show that daily use of flaxseed and flaxseed oil are as effective as mineral oil in treating constipation.
Flaxseed oil comes from the seed of the flax plant. It contains 50 to 60% omega-3 fatty acids in the form of alpha-linolenic acid (ALA). That is more than is contained in fish oil. But the body is not very efficient at converting ALA into the omega-3 fatty acids found in fish oils. So ALA from flaxseed may not have the same benefits as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from fish oil.
Flaxseed oil is available in liquid and softgel capsule forms. Like any oil, flaxseed oil may turn rancid if it is not refrigerated. Flaxseed oil requires special packaging because it is easily destroyed by heat, light, and oxygen. The highest quality flaxseed products are made using fresh pressed seeds, bottled in dark containers, and processed at low temperatures in the absence of light, extreme heat, or oxygen.
Be sure to buy flaxseed oil supplements made by reputable companies who certify their products are free of heavy metals, such as lead and mercury.
How to Take It
The dose depends on how much fatty acids you get in your diet and which condition you are taking flaxseed oil for.
Talk to your doctor or pediatrician before giving flaxseed oil to a child under 18.
There is no recommended dose for flaxseed oil. The best dose for you depends on a number of factors and should be determined in consultation with your doctor.
Flaxseed oil is often used in a liquid form, which contains approximately 7 grams of ALA per 15 mL (1 tbsp), and contains about 130 calories.
Because of the potential for side effects and interactions with medications, you should take dietary supplements only under the supervision of a knowledgeable health care provider.
Flaxseed may slow down the absorption of oral medications or other nutrients if taken at the same time. Try to avoid taking flaxseed at the same time as medications and other supplements.
People with diabetes or schizophrenia may not be able to convert ALA to EPA and DHA, the forms more readily used in the body. People with either condition should get omega-3 fatty acids from dietary sources rich in EPA and DHA, such as fish.
Although studies have found that eating fish (which contains the omega-3 fatty acids EPA and DHA) regularly may reduce the risk of macular degeneration, a recent study including 2 large groups of men and women found that diets rich in ALA may substantially increase the risk of this eye disease. More research is needed. Until then, people with macular degeneration should get omega-3 fatty acids from sources of EPA and DHA (such as fish or fish oil), rather than ALA.
Fish and fish oil may protect against prostate cancer. But ALA may be associated with increased risk of prostate cancer in men. More research is needed. In the meantime, men with prostate cancer should get omega-3 fatty acids from sources of EPA and DHA (such as fish or fish oil), rather than ALA.
If you are being treated with any of the following medications, you should not use flaxseed oil (alpha-linolenic acid or ALA) or other omega-3 fatty acids without talking to your doctor first.
Blood-thinning medications (anticoagulants): Omega-3 fatty acids may strengthen the effects of blood-thinning medications, including aspirin, warfarin (Coumadin), and clopedigrel (Plavix). While the combination of aspirin and omega-3 fatty acids may help treat heart disease, they should not be taken together without the supervision of a doctor.
Blood sugar-lowering medications: Taking omega-3 fatty acid supplements may increase fasting blood sugar levels, which may increase your need for the medications. Use omega-3 fatty acid supplements with caution if you take medicines to lower your blood sugar, such as:
- Glipizide (Glucotrol and Glucotrol XL)
- Glyburide (Micronase or Diabeta)
- Glucophage (Metformin)
Cyclosporine: Taking omega-3 fatty acids during cyclosporine (Sandimmune) therapy may reduce the toxic side effects associated with this medication in transplant patients, such as high blood pressure and kidney damage.
Etretinate and topical steroids: Adding omega-3 fatty acids (specifically EPA) to the drug therapy etretinate (Tegison) and topical corticosteroids may improve symptoms of psoriasis.
Cholesterol-lowering medications: Increasing the amount of omega-3 fatty acids in your diet may help a group of cholesterol lowering medications known as statins work more effectively. These statins include:
- Atorvastatin (Lipitor)
- Lovastatin (Mevacor)
- Simvastatin (Zocor)
Nonsteroidal anti-inflammatory drugs (NSAIDs): In an animal study, treatment with omega-3 fatty acids reduced the risk of ulcers from NSAIDs, including ibuprofen (Motrin or Advil) and naproxen (Aleve or Naprosyn). More research is needed to see whether omega-3 fatty acids would have the same effects in people.
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Steven D. Ehrlich, NMD, Solutions Acupuncture, a private practice specializing in complementary and alternative medicine, Phoenix, AZ. Review provided by VeriMed Healthcare Network. Also reviewed by the A.D.A.M Editorial team.