Larch arabinogalactan is a well known source of dietary fiber that offers
powerful therapeutic benefit as a prebiotic and as a modulator of the immune
system. Of particular interest is its potential as an adjunctive supplement in
the treatment of chronic diseases, including cancer. (1)
Arabinogalactan (AG) is a polysaccharide found in the cell walls of a wide
variety of edible and non-edible, woody plants. The wood of the western larch
tree (Larix occidentalis) provides a rich harvest of free arabinogalactan from
its inner bark. This complex carbohydrate helps the tree recover from injury
from lightning strikes, and protects against the freeze-thaw cycles experienced
in the high altitudes of the Pacific and Inland Northwest where it grows. (2)
Polysaccharides are often found in many medicinal herbs used for immune
enhancement, including Echinacea and Astragalus. (3) AG is a fine, dry,
off-white powder with a mildly sweet taste that mixes well with liquids. This
safe and effective phytochemical is FDA approved for use as a dietary fiber and
as a food additive. There are no known reports of toxicity. Credit for
introducing larch AG into clinical practice goes to the distinguished
naturopathic physician, Dr. Peter D'Adamo.
AG Supports Digestion
Larch AG acts as a food supply to friendly intestinal bacteria. Like the
well-known fructooligosaccharides (FOS), AG is considered a "prebiotic." The
non-absorbed fiber is eagerly fermented by the distal gut microflora, resulting
in an elevated production of short-chain fatty acids (SCFAs)—primarily butyrate,
but also propionate. SCFAs are critically important to the health of the colon
and are the principal energy source (butyrate) for the colonic epithelial cells.
(8,9) Many clinicians use prebiotics to prevent and treat intestinal conditions
like diverticulosis, leaky-gut, irritable bowel syndrome (IBS) as well as
inflammatory bowel diseases (IBD) like Crohn's and ulcerative colitis.
Studies have shown that larch AG consumption reduces intestinal ammonia
generation. (5) Reducing ammonia is significant because even low ammonia levels
can have damaging effects on intestinal colonic cells. (6) AG may especially
benefit patients with liver disease who are unable to detoxify ammonia,
resulting in hepatic encephalopathy. (4,6,7)
AG Enhances Immunity
While larch AG is important for digestive health it has received even more
attention for its ability to promote the health of the immune system. Larch AG
seems to enhance immune response and may be termed a biological response
Larch AG may be important in cancer treatment protocols due to its ability to
block the metastasis of tumor cells to the liver, and to stimulate NK cell
cytotoxicity. (3) Tumor metastasis to the liver is more common than to other
organ sites. AG has been shown to reduce tumor cell colonization and increase
survival time of subjects with various cancers. (12,13,14) Incidentally,
modified citrus pectin has the same anti-metastatic mechanism of action as larch
AG, but does not provide the immune-modulating effects.
NK cell activity is a functional marker for health. In one well-designed study,
larch AG induced an increased release of interferon gamma (IFN gamma), tumor
necrosis factor alpha, interleukin-1 beta (IL-1 beta) and interleukin-6 (IL-6).
This resulted in activating two powerful cells of the immune system: macrophages
and NK cells. It was found that the IFN gamma was most responsible for the
observed enhancement of NK cytotoxicity. (11)
Reports in the medical literature link decreased NK cell activity to a variety
of chronic diseases including chronic fatigue syndrome, (15) viral hepatitis,
(16,17) HIV/AIDS, (3) and autoimmune diseases such as multiple sclerosis. (18)
The ability of larch arabinogalactans to stimulate NK activity might be the
reason for the significantly improved clinical outcome of these patients.
Larch AG has also been shown to decrease the frequency and severity of pediatric
otitis media caused by gram negative rods (especially, Escherichia coli and
Klebsiella sp.) (3) (Note: Xylitol consumption also reduces the incidence of
Larch arabinogalactan in powder form is typically dosed in teaspoons or
tablespoons at a concentration of approximately 3 grams per teaspoon. The adult
dosage is one to three teaspoons per day in divided doses. Because of its mild
taste and excellent solubility in water or juice, it is easy to use with
children. Clinical feedback suggests an occasional reaction of bloating and
flatulence in less than three percent of individuals (mostly women). This side
effect is probably due to the effect AG has on beneficially altering intestinal
microflora and will often disappear after several days to one week. (10)
1. Adams MF, Ettling BV. Industrial Gums 2nd Edition; Academic Press 1973.
2. Chemstone. Theoretical Basis for Process Improvement with Chemstone OAE
3. D'Adamo P. Larch arabinogalactan is a novel immune modulator. Townsend Letter
for Doctors and Patients 1996, July; 156: 42-46.
4. Vince AJ, McNeil NI, Wager JD, Wrong OM. The effect of lactulose, pectin,
arabinogalactan, and cellulose on the production of organic acids and metabolism
of ammonia by intestinal bacteria in a faecal incubation system. Br J Nutr
5. Englyst HN, Hay S, Macfarlane GT. Polysaccharide breakdown by mixed
populations of human faecal bacteria. FEMS Microbiol Ecology 1987;95:163-171.
6. Robinson R, Feirtag J, Slavin J. Effects of dietary arabinogalactan on
gastrointestinal and blood parameters in healthy human subjects. J Amer College
of Nutrition 2001; 20: 279-285.
7. Crociani F, Alessandrini A, Mucci MM, Biavati B. Degradation of complex
carbohydrates by Bifidobacterium spp. Int J Food Microbiol 1994; 24:199-210.
8. Roediger WE. Utilization of nutrients by isolated epithelial cells of the rat
colon. Gastroenterology 1989; 83:424-429.
9.Tsao D, Shi Z, Wong A, Kim YS. Effect of sodium butyrate on carcinoembryonic
antigen production by human colonic adenocarcinoma cells in culture. Cancer Res
10. Kelly GS. Larch arabinogalactan: Clinical relevance of a novel
immune-enhancing polysaccharide. Alternative Med Rev 1994; 4(2):96-103.
11. Hauer J, Anderer FA. Mechanism of stimulation of human natural killer
cytotoxicity by arabinogalactan from Larix occidentalis. Cancer Immunol
12. Hagmar B, Ryd W, Skomedal H. Arabinogalactan blockade of experimental
metastases to liver by murine hepatoma. Invasion Metastasis 1991;11:348-355.
13. Beuth J, Ko HL, Schirrmacher V,et al. Inhibition of liver tumor cell
colonization in two animal tumor models by lectin blocking with D-galactose or
arabinogalactan. Clin Exp Metastasis 1988;6:115-120.
14. Beuth J, Ko HL, Oette K, et al. Inhibition of liver metastasis in mice by
blocking hepatocyte lectins with arabinogalactan infusions and D-galactose. J
Cancer Res Clin Oncol 1987;113:51-55.
15.Levine PH, Whiteside TL,Friberg D, et al. Dysfunction of natural killer cell
activity in a family with chronic fatigue syndrome. Clin Immunol Immunopathol
16. Machado IV, Deibis L, Risquez E, et al. Immunoclinical, molecular, and
immunopathologic approach to chronic viral hepatitis.Therapeutic considerations.
GEN 1994;48:124-132. [article in spanish].
17. Corado J, Toro F, Rivera H, et al. Impairment of natural killer (NK)
cytotoxicity activity in hepatitis C virus (HCV) infection. Clin Exp Immunol
18. Kastrukoff LF, Morgan NG, Zecchini D, et al. A role for natural killer cells
in the immunopathogenesis of multiple sclerosis. J Neuroimmunol 1998;86:123-133.
The information in this article is not intended to provide
personal medical advice, which should be obtained from a medical professional,
and has not been approved by the U.S. FDA.
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