Primary Benefits Educates the immune system featuring Transfer Factor • In an independent study, increased Natural Killer (NK) cell activity 204% above normal response Provides safe and effective support Raise Your Immune I.Q.^{® 4Life Transfer Factor Classic has been recognized for years as the best colostrum-based Transfer Factor product for daily immune system support. It contains our original Transfer Factor XF ®} ingredient for safe and proven immune support. What makes this product unique? Transfer factors are tiny messenger molecules that transmit immunity information from one entity to another, such as between a mother and her breastfeeding infant.In an independent study, 4Life Transfer Factor Classic increased the Natural Killer (NK) cell activity 204 percent above normal immune response. Natural Killer cells are on the front lines of your immune system. Complementary Products RiteStart 4Life Transfer Factor RioVida trade 4Life Transfer Factor PlusAdvanced Formula. This product information is approved for distribution only in the United States.