Larch is indigenous to central Europe, North America, northern Russia, and Siberia. It is in the pine tree family and sheds its needles yearly in the fall. An extract of the tree’s bark and resin has been approved by the FDA as a food additive and fiber supplement. However, though it is largely harmless, scientific research has not shown larch to be an effective treatment or prevention for cancer or any other health issues.

It is thought that larch can be used as a treatment for bronchitis, colds, and other respiratory conditions. Folk medicine indicates that larch can be used in the treatment of rheumatism, jaundice, and skin problems and as a poultice for wounds, swelling, and burns. Native Americans made tea from the needles of the larch tree and drank it as a treatment for coughs and constipation. Larch resin was also used by Native Americans to treat indigestion and kidney and lung disorders. It was administered as a chewing gum.

The active ingredient in larch is an extracted compound sugar, arabinogalactan. This polysaccharide cannot be digested by the body. It is available for purchase as a fiber supplement in powder form. The powder can be mixed with water or juice or can be sprinkled directly on food. It is also available in tablet and capsule form. Ointments, lotions, and oils are also composed of larch resin and can be applied directly to the skin.

Scientific studies have concluded that larch arabinogalactan is a safe compound for human ingestion. A second study found that this compound stimulated white blood cells known as natural killer cells. An animal study using mice contradicted these results, with their findings indicating that larch arabinogalactan suppresses the production of these natural killer cells. A clinical study examining the ability for improving cholesterol, triglycerides, and sugar levels compared larch arabinogalactan with rice starch. At the conclusion of the 6-month trial, there were no differences between patients taking larch arabinogalactan and those given rice starch.

The Larix genus, to which the larch tree belongs, is listed in the FDA’s Poisonous Plant Database, but no toxic effects have been documented in medical literature from use of larch supplements. However, allergic reactions are possible and result in symptoms that include rashes, hives, and contact dermatitis.