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Other common
name(s): larch arabinogalactan, American larch, Eastern
larch, European larch, common larch, tamarack
Scientific/medical
name(s): Larix
occidentalis,
Larix laricina, Larix
decidua, Larix
europaea
Description
A member of the pine family, the larch tree has the unusual
quality of losing its needles each fall. Several types of larch tree
grow in central Europe, North America, northern Russia, and Siberia.
The bark and its resin are used in herbal remedies. An extract of larch
called arabinogalactan is sold as an herbal remedy and fiber
supplement.
Overview
Larch arabinogalactan is approved by the U.S. Food and Drug
Administration (FDA) as a food additive and fiber supplement. However,
available scientific evidence does not support claims that larch bark
is effective in treating cancer or any other disease in humans. Early
laboratory evidence suggested that larch arabinogalactan may stimulate
the immune system. However, a more recent study in mice contradicts
this finding. Further studies are needed to identify other uses for
larch in humans.
How is it promoted for use?
Proponents believe that larch can be used to treat bronchitis,
colds, and other respiratory conditions. Arabinogalactan is promoted to
stimulate the immune system and increase the effectiveness of some
drugs, including chemotherapy medications. Some claim that the compound
also inhibits the spread of cancer to the liver. Larch resin is
recommended to be applied to the skin for wounds and scratches.
What does it involve?
The extract arabinogalactan is a type of complex sugar, called
a polysaccharide or glycan, that the body cannot digest.
Arabinogalactans are also found in some common foods such as tomatoes,
wheat, carrots, certain mushrooms, and other plants. The food additive
gum arabic is a type of arabinogalactan.
Larch arabinogalactan is available as a fiber supplement in
powder form. It can be mixed with water or juice or sprinkled on food.
It can also be bought in capsule and tablet form. Larch resin is
available in ointments, lotions, and oils, often in blends with other
herbs and oils, for application to the skin.
What is the history behind it?
The bark of the larch tree has been used in various folk
medicine traditions to treat rheumatism, jaundice, skin problems, and
as a poultice for wounds, swelling, and burns. Native Americans used
the needles and inner bark to make a tea to treat coughs and
constipation. Resin from the bark was used by Native Americans as a
chewing gum and to relieve indigestion. The resin was also used to
treat kidney and lung disorders and as a dressing for burns and sores.
Larch arabinogalactan was first isolated from the bark of the
larch tree in 1992, although this substance is also available from
other plant sources. The FDA has approved arabinogalactan from both the
Eastern and the Western larch as a food additive, so that it can be
used in foods as an emulsifier, stabilizer, thickener, moisture
retainer, binder, and for other purposes. It is also approved as a
fiber supplement.
What is the evidence?
In one laboratory study, researchers at the University of
Minnesota concluded that larch arabinogalactan is a safe source of
dietary fiber and may be effective in boosting the immune system. The
research was sponsored, however, by the company that owns the patent to
the extract. Another laboratory study done in Germany found that
arabinogalactan from the Western larch stimulated the action of a type
of white blood cell called natural killer cells.
More recently, a brief animal study looked at white blood
cells that serve important immune functions. The researchers found that
arabinogalactan actually seemed to suppress production of some of these
white blood cells, seeming to contradict the results of the earlier
study. With daily injections of arabinogalactan, the mice had fewer
white blood cells in the bone marrow after a week. Levels of natural
killer cells (a type of white blood cell) went back to normal after 2
weeks of injections. Immune cells in the spleen were mostly present in
normal numbers, although the levels of some types of immune cells were
lower in the spleen even when they were normal in the bone marrow.
Further studies are necessary to determine whether arabinogalactan
helps human immune function.
A 2004 human study compared larch arabinogalactan with rice
starch to determine whether it improved cholesterol, triglycerides, and
sugar levels. At the end of 6 months, there were no differences between
the group that received rice starch and the group that received
arabinogalactan.
Little scientific information is available on the effects of
larch resin mixtures on human skin. It may have antiseptic, or
germ-killing, properties.
Are there any possible problems or
complications?
This product is sold as a
dietary supplement in the United States. Unlike companies that produce
drugs (which must provide the FDA with results of detailed testing
showing their product is safe and effective before the drug is approved
for sale), the companies that make supplements do not have to show
evidence of safety or health benefits to the FDA before selling their
products. Supplement products without any reliable scientific evidence
of health benefits may still be sold as long as the companies selling
them do not claim the supplements can prevent, treat, or cure any
specific disease. Some such products may not contain the amount of the
herb or substance that is written on the label, and some may include
other substances (contaminants). Though the FDA has written new rules
to improve the quality of manufacturing processes for dietary
supplements and the accurate listing of supplement ingredients, these
rules do not take full effect until 2010. And, the new rules do not
address the safety of supplement ingredients or their effects on health
when proper manufacturing techniques are used.
Most such
supplements have not been tested to find out if they interact with
medicines, foods, or other herbs and supplements. Even though some
reports of interactions and harmful effects may be published, full
studies of interactions and effects are not often available. Because of
these limitations, any information on ill effects and interactions
below should be considered incomplete.
Larch has been approved by Germany’s Commission E
for external use, and is recommended for colds, coughs, and bronchitis.
The Larix genus is listed in the FDA's Poisonous Plant
Database, although reports of toxic effects were not found in the
medical literature. Kidney damage might occur if the bark is ingested
or if the oils are spread over a large area of the body and absorbed
through the skin.
Larch allergies have not been reported; however, rashes,
hives, and contact dermatitis have occurred in people working with some
species of larch. It is possible that many of these reactions are due
to contact with lichens that grow on the bark of the larch rather than
the larch itself.
The larch extract arabinogalactan is generally recognized as
safe and is approved by the FDA as a food additive and fiber
supplement. However, it contains galactose, a type of sugar, and people
who require a low-galactose diet should avoid arabinogalactan. Those
with lactose intolerance should use the supplement with caution.
Relying on this type of treatment alone and avoiding or delaying
conventional medical care for cancer may have serious health
consequences.
Additional Resources
More information from your American Cancer
Society
The following information on complementary and alternative
therapies may also be helpful to you. These materials may be found on
our Web site (www.cancer.org)
or ordered from our toll-free number (1-800-ACS-2345).
References
Adams J. University of Minnesota researchers uncover
immune-boosting fiber. Minnesota
Daily. January 7,1999.
Blumenthal M, ed. The
Complete German Commission E Monographs: Therapeutic Guide to Herbal
Medicines. Austin, TX: American Botanical Council; 1998.
Bown D. New
Encyclopedia of Herbs & Their Uses. New York, NY:
DK Publishing Inc; 2001.
Center for Food Safety and Applied Nutrition. Agency response
letter: GRAS notice no. GRN 000084. February 19, 2002. US Food and Drug
Administration Web site. http://www.cfsan.fda.gov/~rdb/opa-g084.html.
Accessed June 6, 2008.
Currier NL, Lejtenyi D, Miller SC. Effect over time of in-vivo
administration of the polysaccharide arabinogalactan on immune and
hemopoietic cell lineages in murine spleen and bone marrow. Phytomedicine.
2003;10:145-153.
Gruenwald J. PDR
for Herbal Medicines. 3rd ed. Montvale, NJ: Thomson PDR;
2004.
Hauer J, Anderer FA. Mechanism of stimulation of human natural
killer cytotoxicity by arabinogalactan from Larix occidentalis. Cancer Immunol Immunother.
1993;36:237-244.
Larch arabinogalactan. PDRhealth Web site.
http://www.pdrhealth.com/drug_info/nmdrugprofiles/nutsupdrugs/lar_0320.shtml.
Accessed April 23, 2007..Content no longer available.
Larch. PDRhealth Web site.
http://www.pdrhealth.com/drugs/altmed/altmed-mono.aspx?contentFileName=ame0368.xml&contentName=Larch.
Accessed June 6, 2008.
Larix laricina. US Department of Agriculture Forest Service
Web site.
http://www2.fpl.fs.fed.us/TechSheets/SoftwoodNA/pdf_files/larixlariceng.pdf.
Accessed June 6, 2008.
Lichens. DermNet NZ Web site.
http://www.dermnetnz.org/dermatitis/plants/lichen.html. Updated March
18, 2008. Accessed June 6, 2008.
Marett R, Slavin JL. No long-term benefits of supplementation
with arabinogalactan on serum lipids and glucose. J Am Diet Assoc.
2004;104:636-639.
Robinson RR, Feirtag J, Slavin JL. Effects of dietary
arabinogalactan on gastrointestinal and blood parameters in healthy
human subjects. J Am
Coll Nutr. 2001;20:279-285.
Note: This information may not cover
all possible claims, uses, actions, precautions, side effects or
interactions. It is not intended as medical advice, and should not be
relied upon as a substitute for consultation with your doctor, who is
familiar with your medical situation.
Last Medical Review: 11/01/2008
Last Revised: 11/01/2008
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