Arabinogalactins, substances found in many plants, are long
molecules made of the sugars galactose and arabinose linked
together in a chain. Arabinogalactan extracted from the Western
larch tree (larch arabinogalactan, or LA) has been proposed as
an immune stimulant. animal studies suggest that LA has several
potentially positive effects on the immune system. It appears to
activate a type of white blood cell called a “natural killer” or
NK cell, and perhaps other white blood cells as well, and also
possibly alter levels of immune-related substances such as
interleukins, interferon, and properdin.1-5 On the basis of
these findings, LA has been advocated as a supplement for
general immune support. However, this recommendation is
premature. It is a very, very long way from basic science of
this type to evidence that a treatment has real effectiveness.
Many plant substances appear to activate the immune system; this
may be merely because the immune system regards them as “the
enemy,” and mobilizes to fight them.