FDA's Role in Food Defense. Links to the Acts, Presidential Policy Directives (PPD), and Homeland Security Presidential Directives (HSPD) which outline actions/responsibilities in support of prevention in and protection of the nation's food and food supply are provided for your reference.inks to the Acts, Presidential Policy Directives (PPD), and Homeland Security Presidential Directives (HSPD) which outline actions/responsibilities in support of prevention in and protection of the nation's food and food supply are provided for your reference.