Here at Fix Your Gut we have written a lot about different prebiotics and how their use may or may not help improve your digestive health. There are few prebiotics that I recommend; there are some that I am more reserved to recommend, and one that I believe should be supplemented only in people who have healthy digestion. There are more and more prebiotic supplements coming out onto the market, and some that have been out there for a while but are lesser known. I will eventually write about the widely discussed prebiotic fiber that Dr. Mark Pimentel believes is the best for people that have SIBO (small intestinal bacterial overgrowth), hydrolyzed guar gum (GOS and 2-FL in my opinion are better prebiotics).

Arabinogalactan falls into two different categories for me; it is both a lesser known prebiotic and one with niche uses.

What Are Arabinogalactans?

Arabinogalactans are polysaccharides that are found in plants and even Mycobacterial cell walls. Arabinogalactan consists of chains or arabinose and galactose monosaccharides. You can either ingest arabinogalactans through diet or prebiotic supplements. Good sources of arabinogalactans found in diet are:1 2

  • Carrots
  • Radishes
  • Pears
  • Corn
  • Tomatoes
  • Coconut meat and milk

Arabinogalactans are also found in some common herbs that people use to improve their health. They include:3 4

  • Echinacea purpurea
  • Curcuma longa
  • Viscum album (mistletoe)

The Supposed Benefits of Ingesting Arabinogalactans

There are various reported benefits of ingesting arabinogalactans for improving your immune system and your digestive health.

Ingesting arabinogalactans improve your digestive system in multiple ways as a reduced fermentation potential prebiotic fiber. The prebiotic fiber has shown in studies to favor butyrate production (an important SCFA [short chain fatty acid] for intestinal mucosal integrity), increase production of the SCFA propionate, and slightly increase production of the SCFA acetate, lower colonic pH, and decrease the generation/absorption of ammonia in the digestive system. It has also been shown to favor selective probiotic bacteria including Bifidobacteria and Lactobacillus and seems to discourage the growth of opportunistic Clostridia and E. coli. It is unknown if Klebsiella ferments the prebiotic, but in studies, it appears that it does up-regulate the immune system to keep opportunistic gram-negative bacteria like Klebsiella from becoming overgrown. Arabinogalactan ingestion might also reduce bacterial adherence and biofilm formation. The benefits on the microbiome of ingesting arabinogalactans seem to be comparable to my recommended prebiotic, GOS.5 6 7 8 9

Arabinogalactans have been shown to increase immune system function in in-vitro studies. It appears that the immune modulating properties of Echinacea purpurea might be from the arabinogalactans that the herb contains. Arabinogalactans have been shown to:

  • Enhance function of natural killer cells. NK cells help our bodies by preventing cancer metastasis (regulate cytotoxicity) and fight viruses. Mistletoe has reported anti-cancer effects may stem from its concentration of arabinogalactans.10 11
  • Increase macrophage activation against pathogens.12 13
  • Increased production of TNF-alpha, interleukin-1, and interferon-beta to help our immune system fight pathogens.14 15
  • Have anti-metastasis properties (in-vitro, and in-vivo animal studies).16 17
  • Reduce pediatric occurrences of otitis media.18 19

Potential Negatives of Ingesting Arabinogalactans

Ingestion of arabinogalactans in food sources, in supplemental form, or within herbs may have specific benefits to improve your health. There are sadly some proposed drawbacks to its use.

Arabinogalactans are also a component of Mycobacteria cell walls. The mechanism of action for the antitubercular drug ethambutol might occur from inhibition of Mycobacteria arabinogalactan synthesis. Ethambutol reduces Mycobacteria concentrations by counteracting the enzyme arabinosyl transferase, reducing arabinogalactan synthesis, and increasing cell wall permeability. It is unknown if ingesting arabinogalactans while suffering from Mycobacterial dysbiosis, especially if you are suffering from for example Mycobacterium avium paratuberculosis dysbiosis (the cause of both ulcerative colitis and Crohn’s disease), would cause any issues or increase in Mycobacterial virulence or concentration. That being said, there are probably different arabinogalactan receptors between what the Mycobacteria produce and what we ingest. I would caution anyone with Mycobacteria infections to reduce their consumption and do not supplement with this prebiotic fiber until more studies can be performed.20 21

There are not many studies on what opportunistic organisms may use arabinogalactans for energy. We know, however, through studies that opportunistic bacteria including Clostridia, E. coli, and possibly Klebsiella do not prefer the prebiotic and that it may reduce their colonization in our digestive tract. Some yeast strains can ferment arabinose for energy, so if you have yeast dysbiosis and react negatively to arabinogalactans, I would reduce or eliminate the amount of the prebiotic you ingest.22

Finally, there was one in-vivo study done with arabinogalactan ingestion that does cast doubt on some of its ability to help improve digestive health. In the study only Lactobacillus was shown to increase through supplementation, SCFA amounts did not improve, and Clostridia increased slightly as well. I do have issues with this study, they sampled fecal flora instead of colonic flora biopsies, it can be difficult to obtain SCFA information from fecal samples because most are reabsorbed by the gut, they used significant amounts of arabinogalactan (fifteen and thirty grams), and it was generously sweetened with aspartame (could have an adverse effect on the probiotic microbiome). That being said the study’s authors marked one important conclusion, the more arabinogalactan one consumes (thirty grams in the study), the greater chance of fermentation side effects like bloating and flatulence, and it seems that an increased dosage does not correlate to its effectiveness, just length of time.23

Arabinogalactan Supplementation Recommendations

If you want to try arabinogalactans as a prebiotic, I suggest you take in five to ten grams daily for at least a month to see if you have any improvement in your overall health. Not everyone can tolerate prebiotics, so if it causes excessive side effects like flatulence and bloating after a few days of consuming it, it might be best to try lower doses or discontinue its use.

Most arabinogalactan supplements are sourced from the bark of the larch tree.

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