Flaxseed and flaxseed oil (Linum usitatissimum)
Natural Standard® Patient Monograph, Copyright © 2013 (www.naturalstandard.com). All Rights Reserved. Commercial distribution prohibited. This monograph is intended for informational purposes only, and should not be interpreted as specific medical advice. You should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.
Flaxseed and its derivative flaxseed oil (or linseed oil) are rich sources of the essential fatty acid alpha-linolenic acid (ALA), which is a biologic precursor to omega-3 fatty acids such as eicosapentaenoic acid. Although omega-3 fatty acids have been associated with improved cardiovascular outcomes, evidence from human trials is mixed regarding the efficacy of flaxseed products for coronary artery disease or hyperlipidemia (high lipid levels).
The lignans of flaxseed (not flaxseed oil) possess in vitro antioxidant and estrogen-like properties, prompting theories about their efficacy for the treatment of breast cancer. However, there is not sufficient human evidence to make a strong conclusion. As a source of fiber, flaxseed (not flaxseed oil) taken by mouth possesses laxative properties. In large doses, or when taken with inadequate water, flaxseed may cause bowel obstruction. The effects of flaxseed on blood glucose levels are not clear, although hyperglycemic (increased blood sugar) effects have been reported with omega-3 fatty acids in general.
Flaxseed oil contains only the ALA component of flaxseed and not the fiber or lignan components. Therefore, flaxseed oil may share the purported lipid-lowering properties of flaxseed but not its proposed laxative or anticancer abilities.