Dec 7 (Reuters) - Gnc Holdings Inc :
* GNC comments on agreement with department of justice
* Under agreement, "GNC will take a number of actions to broaden industry-wide knowledge of prohibited ingredients"
* Under agreement, co "will improve compliance by vendors of third party products"
* DOJ found evidence that USP labs provided false assurances and information and fake documentation to third parties, including GNC Source text for Eikon: Further company coverage: