blood cholesterol levels in animal studies, but few
high-quality human studies have been done using
flax products. Results that do exist have been mixed.
Another health claim for flaxseed (but not flax oil)
is that it has anti-cancer properties. Flaxseed and ses-
ame seed both contain large amounts of lignans.
Lignans are naturally occurring molecules found in
plants that mimic the effect of the female hormone
estrogen. Lignans compete with estrogen for binding
sites on cells. They can either act as antagonists and
lessen the estrogen response where there is continual
estrogen exposure (increasing risk of breastcancer)or
they can mimic estrogen and boost the response where
exposure is limited (post menopause) helping to pre-
vent post menopausal symptoms. Few well-designed,
well-controlled human studies of the effect of lignans
on cancer have been completed. Although the results
of animal studies are encouraging, there is not enough
evidence to say that lignans, or flaxseed, can slow or
prevent cancer.
Researchers generally agree that ground flaxseed
is an effective laxative. Flaxseed provides dietary fiber
and, along with the oil it naturally contains, helps
move material through the bowel. Whole seed may
have the reverse effect, swelling and blocking the
bowel.
Some studies have shown that flaxseed oil sup-
plements can reduce symptoms of attention deficit-
hyperactivity disorder (ADHD) in some children.
Other studies claim that flaxseed can lower blood
sugar levels in people with diabetes. Initial results
also suggest that flaxseed may reduce symptoms of
menopause. None of these health claims have been sub-
stantiated with large, well-controlled human studies.
Precautions
ALA, which is found in large quantities in flax-
seed, appears to increase the risk of developingpros-
tatecancer. This finding is preliminary and not yet
substantiated. Individuals with prostate cancer or a
history of prostate cancer should consult their oncol-
ogist before using flax products.
Although no health risks are known when flaxseed
and flax oil are used in reasonable and moderate quan-
tities, no studies have been done on the safety of flax in
pregnant orbreastfeedingwomen or in children.
Interactions
No specific drug interactions are known.
Complications
Complications are unlikely to occur when flax
products are used to meet daily dietary needs. Whole
flaxseed can cause blockage of the intestines when
taken with inadequate amounts of liquids.
Parental concerns
Parents should be aware that the safe dose of
many herbal supplements has not been established
for children. Accidental overdose may occur if chil-
dren are given adultdietary supplements.
Resources
BOOKS
Muir, Alister D., and Neil D. Westcott, eds.Flax: The Genus
Linum.New York: Routledge 2003.
PDR for Herbal Medicines,3rd ed. Montvale, NJ: Thomp-
son Healthcare, 2004.
Pierce, Andrea.The American Pharmaceutical Association
Practical Guide to Natural Medicines.New York: Wil-
liam Morrow, 1999.
Reinhardt-Martin, Jane.The Amazing Flax Cookbook.
Moline: IL, TSA Press, 2004.
Wildman, Robert E. C., ed.Handbook of Nutraceuticals
and Functional Foods,2nd ed. Boca Raton, FL: CRC/
Taylor&Francis, 2007.
PERIODICALS
Covington, M. B. ‘‘Omega-3 Fatty Acids.’’American Family
Physician70, no.1 (2004): 133-40.
ORGANIZATIONS
Alternative Medicine Foundation. P.O. Box 60016, Poto-
mac, MD 20859. Telephone: (301) 340-1960. Fax: (301)
340-1936. Website:<http://www.amfoundation.org>.
Flax Council of Canada. 465-167 Lombard Avenue, Win-
nipeg, MB R3B 0T6. Telephone: (204) 982-2115. Fax:
(204) 942-1841. Website:<http://www.flaxcouncil.ca>.
Natural Standard. 245 First Street, 18th Floor, Cambridge,
MA 02142. Telephone: (617) 444-8629. Fax: (617) 444-
- Website:http://www.naturalstandards.com.
Office of Dietary Supplements, National Institutes of
Health. 6100 Executive Blvd., Room 3B01, MSC 7517,
Bethesda, MD 20892-7517. Telephone: (301) 435-2920.
Fax: (301) 480-1845. Website:http://dietary-
supplements.info.nih.gov.
OTHER
Carter, Jack. ‘‘Flaxseed as Functional Food for People and
as Feed for Other Animals.’’ North Dakota State Uni-
versity. [cited May 7, 2007].http://www.ag.ndsu.
nodak.edu/plantsci/flaxseed.htm.
Flax FAQ. Flax Council of Canada. [cited May 7, 2007].
http://www.flaxcouncil.ca/english/index.php?p=
faq.
‘‘Flaxseed and Flaxseed Oil.’’ National Center for Comple-
mentary and Alternative Medicine. June 1, 2006. [cited
Flaxseed