Noni has been in use as a medicinal herb in various cultures around the world for several thousand years.  Its traditional use relating to immunity includes combating bacterial, viral, fungal, and parasitic infections.  It is used to help respiratory disorders, sore throat, gum infections, fever, headache, diarrhea, and indigestion.  It is considered to have anti-inflammatory effects and is also a common remedy for joint pain. 

There is a large jump from traditional uses to a more scientific understanding of how Noni may work.  Recent studies are helping to explain how Noni supports immune health. 

Dendritic cells are the important cells of your immune system that identify an invader and then help mount the higher-powered adaptive immune response.  A May 2009 study showed that Noni activated dendritic cells and consequently boosted the production of B cells that make antibodies against a specific invader.  This type of boosting of the adaptive immune system is relevant to fighting the flu, as well as other infections. 

Another study showed that Noni goes to work right away to boost the important natural killer cells, a vital part of the front line innate immune system.  Yet another study shows that Noni activates macrophages (front line innate immunity) by stimulating their receptors (cannabinoid 2 receptors -CB2), while simultaneously increasing interferon production (a signal that stimulates dendritic cells to mount the adaptive immune response).

A study with newborn calves showed that Noni could boost the natural defense system against E. coli.

A number of researchers are conforming that Noni activates multiple immune cells.  In one animal study this led to significant anti-tumor activity - information that is consistent with a better immune response for fighting infection.

Other interesting studies on Noni show that it exerts an anti-inflammatory effect and protects the liver.  One study showed that Noni helps the liver make less xanthine oxidase, a finding that supports the traditional use of Noni for gout.  Noni is not only non-toxic at very high doses it has been shown to reduce liver lesions upon toxic exposure.  Thus, Noni facilitates the needed inflammation of the natural immune response as well as offering anti-inflammatory protection for healthy cells while it assists the liver to perform better under stress.

Another property of Noni is that it has relaxing attributes, accomplished by helping to potentiate the relaxing neurotransmitter system of GABA.  This feature will help calm stress during the day (which is immune suppressive) as well as making Noni a good choice for a before bed immune support nutrient that is likely to contribute to restful sleep.

Collectively, this data shows that Noni activates macrophages and natural killer cells of the front line immune troops (innate immunity) while also stimulating dendritic cells to activate T cells and mount antibody production by the higher-powered adaptive immune system.

All of this newer science supports Noni's traditional use with sore throats, respiratory problems, and bacterial and viral infections.  Since it also has a gentle-on-your-body profile, I think it is reasonable to consider Noni as an option in your immune support toolbox during any cold and flu season.  Of course, Noni has not been proven to kill or prevent the H1N1 swine flu, but its theory of operation is supportive of a natural robust immune response.