An online system generates a feed of content for a user that includes content items provided by, or otherwise related to, other users who are connected to the user via the online system. The online system supplements the feed with additional content items that are not related to users who are connected to the user but are likely to be of interest to the user. The additional content items may be associated with users who are connected to additional users who are connected to the user, content items having received a threshold amount of interacting by other users, content items provided by users who provided other content with which the user interacted, or have other characteristics. The additional content items and content items associated with users connected to the user are included in one or more selection processes that generate the feed for the user.