4Life Transfer Factors aren't vitamins, minerals, herbs, or fruit. They are messenger molecules that teach immune cells what they ought to be doing. Transfer Factor messenger molecules can be found within the bodies of mammals and birds. 4Life extracts transfer factors from cow colostrum and chicken egg yolks. Cow colostrum, for example, contains many immune building blocks, but most of these can't be transferred from a cow to a human. However, the power of transfer factors can. 4Life Transfer Factor uses a highly-specialized filtration process, so you get all of that concentrated transfer factor goodness and none of the fillers your body can't use.