Larch arabinogalactan is a natural source of fiber in the form of a dietary supplement. It suggested to be beneficial when used in conjunction with traditional medicine to treat people with chronic illnesses such as cancer, autoimmune disorders, or those with chronic or recurring constipation due to poor diet. Larch arabinogalactin comes from a tree which is native around the world, but the most concentrated source is the Pacific Northwest.

The second part of this supplement's name, "arabinogalactan," is the name of a polysaccharide, or complex carbohydrate, which is found in the walls of certain plant cells. Since the arabinogalactan is a complex sugar, it protects the tree from injury during freeze-thaw cycles, as well as damage from lightning strikes. The western larch is believed to be a lucrative source of arabinogalactan, as large amounts of this substance can be found in the tree’s bark. This particular larch is also found in some inland locations.

Introduced into clinical practice by American doctor Peter D'Adamo in the 1980s, larch arabinogalactan is used to treat gastrointestinal disorders such as irritable bowel syndrome and Crohn's disease. It may also be useful to those with liver ailments because it is capable of reducing ammonia in the human body and reducing stress on the liver. Polysaccharides are often used as an ingredient in many health foods and medicinal herbs that are used to boost the immune system. Larch arabinogolactan is indicated for this purpose as well. In its processed form, it is generally available in a fine white powder with what many describe as a slightly sweet taste.

Digestive health is not the only proposed benefit of larch arabinogalactan. Many studies have been conducted concerning its use as a possible supplement for cancer patients. Studies conducted in 1987 and 1991 indicated a decrease in metastasis, the spreading of cancer cells, in rats with tumors of the liver and spleen. These results, however, have not been clinically validated in human subjects.

The average adult dose is 1 teaspoon (about 3 grams) once a day mixed with water or juice. Some nutritionists, however, recommend dividing this amount into separate doses and taking them every eight hours for maximum benefit. Larch arabinogalactan is Food and Drug Administration (FDA) -approved for use as a dietary supplement, and there have been no reported cases of overdose or toxicity. The only known side effects are bloating and flatulence reported in about 3 to 5 percent of users. Most nutritionists claim these side effects are temporary and will diminish as a person’s body adjusts to the supplement.