Flaxseed and Flaxseed Oil

On this page:

• Introduction
• What Flaxseed Is Used For
• How Flaxseed Is Used
• What the Science Says
• Side Effects and Cautions
• Sources
• For More Information

Introduction

This fact sheet provides basic information about flaxseed and flaxseed oil—common names, uses, potential side effects, and resources for more information. Flaxseed is the seed of the flax plant, which is believed to have originated in Egypt. It grows throughout Canada and the northwestern United States. Flaxseed oil comes from flaxseeds.

What Flaxseed Is Used For

• Flaxseed is most commonly used as a laxative.
• Flaxseed is also used for hot flashes and breast pain.
• Flaxseed oil is used for different conditions than flaxseed, including arthritis.
• Both flaxseed and flaxseed oil have been used for high cholesterol levels and in an effort to prevent cancer.

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How Flaxseed Is Used

Whole or crushed flaxseed can be mixed with water or juice and taken by mouth. Flaxseed is also available in powder form. Flaxseed oil is available in liquid and capsule form. Flaxseed contains lignans (phytoestrogens, or plant estrogens), while flaxseed oil preparations lack lignans.

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What the Science Says

• Flaxseed contains soluble fiber, like that found in oat bran, and may have a laxative effect.
• Studies of flaxseed preparations to lower cholesterol levels report mixed results. A 2009 review of the clinical research found that cholesterol-lowering effects were more apparent in postmenopausal women and in people with high initial cholesterol concentrations.
• Some studies suggest that alpha-linolenic acid (a substance found in flaxseed and flaxseed oil) may benefit people with heart disease. But not enough reliable data are available to determine whether flaxseed is effective for heart conditions.
• Study results are mixed on whether flaxseed decreases hot flashes.
• Although some population studies suggest that flaxseed might reduce the risk of certain cancers, there is not enough research to support a recommendation for this use.
• NCCAM is funding studies on flaxseed. Recent studies are looking at its potential role in preventing or treating atherosclerosis (hardening of the arteries), breast cancer, and ovarian cysts.

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Side Effects and Cautions

• Flaxseed and flaxseed oil supplements seem to be well tolerated. Few side effects have been reported.
• Flaxseed, like any supplemental fiber source, should be taken with plenty of water; otherwise, it could worsen constipation or, in rare cases, even cause intestinal blockage. Both flaxseed and flaxseed oil can cause diarrhea.
• The fiber in flaxseed may lower the body’s ability to absorb medications that are taken by mouth. Flaxseed should not be taken at the same time as any conventional oral medications or other dietary supplements.
• Tell all your health care providers about any complementary and alternative practices you use. Give them a full picture of what you do to manage your health. This will help ensure coordinated and safe care. For tips about talking with your health care providers about CAMA group of diverse medical and health care systems, practices, and products that are not presently considered to be part of conventional medicine. Complementary medicine is used together with conventional medicine, and alternative medicine is used in place of conventional medicine., see NCCAM’s Time to Talk campaign.

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Sources

• Flaxseed. In: Blumenthal M, Goldberg A, Brinckman J, eds. Herbal Medicine: Expanded Commission E Monographs. Newton, MA: Lippincott Williams &amp Wilkins; 2000:134–138.
• Flaxseed. Natural Medicines Comprehensive Database Web site. Accessed at www.naturaldatabase.com on July 10, 2009.
• Flaxseed and flaxseed oil (Linum usitatissimum). Natural Standard Database Web site. Accessed at www.naturalstandard.com on July 10, 2009.
• Flaxseed oil. Natural Medicines Comprehensive Database Web site. Accessed at www.naturaldatabase.com on July 10, 2009.
• Pan A, Yu D, Demark-Wahnefried W. Meta-analysis of the effects of flaxseed interventions on blood lipids. American Journal of Clinical Nutrition. 2009;90(2):288–297.

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