Flaxseed and Flaxseed Oil 

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. 

Common Names—flaxseed, linseed 

Latin Name—Linum usitatissimum 

What It 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. 

How It 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. 

What the Science Says 

•	 Flaxseed contains soluble fiber, like that found in oat bran, and is an 

effective laxative. 

•	 Studies of flaxseed preparations to lower cholesterol levels report 

mixed results. 

•	 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. 

•	 NCCAM is funding studies on flaxseed. Recent studies have looked at the 

effects of flaxseed on high cholesterol levels, as well as its possible role in 

preventing conditions such as heart disease and osteoporosis. 
 

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. 

•	 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 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. 

Sources 

Flaxseed. Natural Medicines Comprehensive Database Web site. Accessed at http://www.naturaldatabase.com on 

July 3, 2007. 

Flaxseed oil. Natural Medicines Comprehensive Database Web site. Accessed at http://www.naturaldatabase.com on 

July 3, 2007. 

Flaxseed and flaxseed oil (Linum usitatissimum). Natural Standard Database Web site. Accessed at 

http://www.naturalstandard.com on June 28, 2007. 

Flaxseed. In: Blumenthal M, Goldberg A, Brinckman J, eds. Herbal Medicine: Expanded Commission E Monographs. Newton, 

MA: Lippincott Williams & Wilkins; 2000:134-138. 

For More Information 

Visit the NCCAM Web site at nccam.nih.gov and view: 

•	 What’s in the Bottle? An Introduction to Dietary Supplements at nccam.nih.gov/health/bottle/ 

•	 Herbal Supplements: Consider Safety, Too at nccam.nih.gov/health/supplement-safety/ 

NCCAM Clearinghouse 

Toll-free in the U.S.: 1-888-644-6226 

TTY (for deaf and hard-of-hearing callers): 1-866-464-3615 

E-mail: info@nccam.nih.gov 

CAM on PubMed 

Web site: nccam.nih.gov/camonpubmed/ 

NIH Office of Dietary Supplements 

Web site: www.ods.od.nih.gov 

NIH National Library of Medicine’s MedlinePlus 

Flaxseed Listing: www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html 

This publication is not copyrighted and is in the public domain. Duplication is encouraged. 

NCCAM has provided this material for your information. It is not intended to substitute 

for the medical expertise and advice of your primary health care provider. We encourage 

you to discuss any decisions about treatment or care with your health care provider. The 

mention of any product, service, or therapy is not an endorsement by NCCAM. 

National Institutes of Health 

♦♦♦

U.S. Department of Health and Human Services 

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Created May 2006 

Updated April 2008 

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