Herbs for Health: Enhance your Natural Killer Cells

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A recent study found that extracts of echinacea (Echinacea purpurea) and Asian ginseng (Panax ginseng) may protect against immune system diseases by enhancing the ability of the body’s natural killer cells to destroy invading viruses. Natural killer cells, large granular lymphocytes found in the blood and lymph, are one of the body’s first lines of defense: They can dissolve and kill any virus-infected or tumor cell even before the immune system is activated.

Natural killer cell activity measured in blood samples taken from twenty healthy persons, twenty with acquired immunodeficiency syndrome (AIDS), and twenty with ­chronic fatigue syndrome, as expected, was significantly diminished in the individuals with AIDS and chronic fatigue syndrome compared to that in healthy people. When various concentrations of echinacea and ginseng extracts were incubated with blood cell cultures, natural killer cell activity increased significantly in all three groups compared with that in untreated blood cells. Echinacea was slightly more effective than ginseng. Even at a concentration of 1 mg/ml, neither extract destroyed monocytes (white blood cells that become macrophages, another type of killer cell).

These findings call for clinical trials testing whether taking oral extracts of echinacea or ginseng also increases natural killer cell activity.

Steven Foster is an author, photographer and consultant specializing in medicinal plants.


See, D. M., et al. “In Vitro Effects of Echinacea and Ginseng on Natural Killer and Antibody-Dependent Cell Cytotoxicity in Healthy Subjects and Chronic Fatigue Syndrome or Acquired Immunodeficiency Syndrome Patients”. Immunopharmacology 1997, 35:229–235.