Arabinogalactans are a class of fibers found in many plants. Common sources are echinacea plants and larch trees. There are various arabinogalactans of several molecular sizes. Larger molecular weight arabinogalactans serve as significant new pre-biotics (food for probiotic bacteria) and also as valuable immune enhancers. Human studies have demonstrated their ability to increase the population of anaerobic bacteria in the colon by anywhere from 40% to 1000% depending on lifestyle factors. Increased anaerobes in the colon are beneficial because additional fermentation (breakdown of the arabinogalactans) lowers colon pH and increases the production of short chain fatty acids (butyric and propionic). Lower pH is known to protect against colon cancer and disorders of the bowel.
Short chain fatty acids nourish colonocytes and are the major food source for hepatocytes in the liver. Through their role as pre-biotics, larger molecular weight arabinogalactans increase populations of lactobacilli and bifidobacteria by 47% to 300% in the gastrointestinal tract.
At the same time, pathogenic bacteria may be reduced by 15.5 to 18.5%.Smaller molecualr weight arabinogalactans can stimulate natural killer cell cytotoxicity, inhibiting metastases to the liver and generally help build a more responsive immune system. They are 50% to 100% more effective as immune boosters depending on which aspect of the immune response is measured. Arabinogalactans from larch are even more effective than echinacea at stimulating macrophages and natural killer cell activity while also increasing the number of NK cellsWhile the effectiveness of echinacea decreases as dosages are increased, larch arabinogalactans evidenced no decline in performance as dosages increase, and, in fact, were four times more effective at equal dosages. Arabinogalactans also increase the release of interferon-gamma, tumor necrosis factor-alpha, and interleukin-1 beta. Beta glucans have similar effects at dosages lower than 25 mg.