diff --git a/core/modules/aggregator/aggregator.pages.inc b/core/modules/aggregator/aggregator.pages.inc
index b1d8081..2a1e2e3 100644
--- a/core/modules/aggregator/aggregator.pages.inc
+++ b/core/modules/aggregator/aggregator.pages.inc
@@ -112,7 +112,17 @@ function aggregator_page_category_form($form, $form_state, $category) {
  *   An array of the feed items.
  */
 function aggregator_load_feed_items($type, $data = NULL, $limit = 20) {
-  Drupal::entityManager()->getStorageController('aggregator_item')->loadFeedItems($type, $data, $limit);
+  $storage_controller = Drupal::entityManager()->getStorageController('aggregator_item');
+  switch ($type) {
+    case 'sum':
+      return $storage_controller->loadFeedItems($limit);
+
+    case 'source':
+      return $storage_controller->loadFeedItemsBySource($data->id(), $limit);
+
+    case 'category':
+      return $storage_controller->loadFeedItemsByCategory($data->cid, $limit);
+  }
 }
 
 /**
diff --git a/core/modules/aggregator/lib/Drupal/aggregator/ItemStorageController.php b/core/modules/aggregator/lib/Drupal/aggregator/ItemStorageController.php
index 634498f..cd264b6 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/ItemStorageController.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/ItemStorageController.php
@@ -7,9 +7,10 @@
 
 namespace Drupal\aggregator;
 
-use Drupal\Core\Entity\DatabaseStorageControllerNG;
 use Drupal\aggregator\Plugin\Core\Entity\Item;
-use Drupal\Core\Entity\EntityInterface;
+use Drupal\Core\Database\Query\PagerSelectExtender;
+use Drupal\Core\Database\Query\SelectInterface;
+use Drupal\Core\Entity\DatabaseStorageControllerNG;
 
 /**
  * Controller class for aggregators items.
@@ -116,31 +117,49 @@ public function saveCategories(Item $item) {
   /**
    * {@inheritdoc}
    */
-  public function loadFeedItems($type, $data = NULL, $limit = 20) {
-    switch ($type) {
-      case 'sum':
-        $query = $this->database->select('aggregator_item', 'i');
-        $query->join('aggregator_feed', 'f', 'i.fid = f.fid');
-        $query->fields('i', array('iid'));
-        break;
+  public function loadFeedItems($limit = 20) {
+    $query = $this->database->select('aggregator_item', 'i');
+    $query->join('aggregator_feed', 'f', 'i.fid = f.fid');
+    $query->fields('i', array('iid'));
+    return $this->executeFeedItemQuery($query, $limit);
+  }
 
-      case 'source':
-        $query = $this->database->select('aggregator_item', 'i');
-        $query
-          ->fields('i', array('iid'))
-          ->condition('i.fid', $data->id());
-        break;
+  /**
+   * {@inheritdoc}
+   */
+  public function loadFeedItemsBySource($fid, $limit = 20) {
+    $query = $this->database->select('aggregator_item', 'i');
+    $query
+      ->fields('i', array('iid'))
+      ->condition('i.fid', $fid);
+    return $this->executeFeedItemQuery($query, $limit);
+  }
 
-      case 'category':
-        $query = $this->database->select('aggregator_category_item', 'c');
-        $query->leftJoin('aggregator_item', 'i', 'c.iid = i.iid');
-        $query->leftJoin('aggregator_feed', 'f', 'i.fid = f.fid');
-        $query
-          ->fields('i', array('iid'))
-          ->condition('cid', $data->cid);
-        break;
-    }
+  /**
+   * {@inheritdoc}
+   */
+  public function loadFeedItemsByCategory($cid, $limit = 20) {
+    $query = $this->database->select('aggregator_category_item', 'c');
+    $query->leftJoin('aggregator_item', 'i', 'c.iid = i.iid');
+    $query->leftJoin('aggregator_feed', 'f', 'i.fid = f.fid');
+    $query
+      ->fields('i', array('iid'))
+      ->condition('cid', $cid);
+    return $this->executeFeedItemQuery($query, $limit);
+  }
 
+  /**
+   * Helper method to execute an item query.
+   *
+   * @param SelectInterface $query
+   *   The query to execute.
+   * @param int $limit
+   *   (optional) The number of items to return. Defaults to 20.
+   *
+   * @return \Drupal\aggregator\ItemInterface[]
+   *   An array of the feed items.
+   */
+  protected function executeFeedItemQuery(SelectInterface $query, $limit) {
     $result = $query
       ->extend('Drupal\Core\Database\Query\PagerSelectExtender')
       ->limit($limit)
@@ -150,4 +169,5 @@ public function loadFeedItems($type, $data = NULL, $limit = 20) {
 
     return $this->loadMultiple($result->fetchCol());
   }
+
 }
diff --git a/core/modules/aggregator/lib/Drupal/aggregator/ItemStorageControllerInterface.php b/core/modules/aggregator/lib/Drupal/aggregator/ItemStorageControllerInterface.php
index bfb689a..f9fa154 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/ItemStorageControllerInterface.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/ItemStorageControllerInterface.php
@@ -43,28 +43,40 @@ public function deleteCategories(array $entities);
   public function saveCategories(Item $item);
 
   /**
-   * Loads and optionally filters feed items.
+   * Loads feed items from all feeds.
    *
-   * @param string $type
-   *   The type of filter for the items. Possible values are:
-   *   - sum: No filtering.
-   *   - source: Filter the feed items, limiting the result to items from a
-   *     single source.
-   *   - category: Filter the feed items by category.
-   * @param mixed $data
-   *   Feed or category data used for filtering. The type and value of $data
-   *   depends on $type:
-   *   - source: $data is an object with $data->fid identifying the feed used to
-   *     as filter.
-   *   - category: $data is an array with $data['cid'] being the category id to
-   *     filter on.
-   *   The $data parameter is not used when $type is 'sum'.
    * @param int $limit
-   *   (optional) The number of records to return. Defaults to 20.
+   *   (optional) The number of items to return. Defaults to 20.
    *
    * @return \Drupal\aggregator\ItemInterface[]
    *   An array of the feed items.
    */
-  public function loadFeedItems($type, $data = NULL, $limit = 20);
+  public function loadFeedItems($limit = 20);
+
+  /**
+   * Loads feed items filtered by a feed.
+   *
+   * @param int $fid
+   *   The feed ID to filter by.
+   * @param int $limit
+   *   (optional) The number of items to return. Defaults to 20.
+   *
+   * @return \Drupal\aggregator\ItemInterface[]
+   *   An array of the feed items.
+   */
+  public function loadFeedItemsBySource($fid, $limit = 20);
+
+  /**
+   * Loads feed items from all feeds.
+   *
+   * @param int $cid
+   *   The category ID to filter by.
+   * @param int $limit
+   *   (optional) The number of items to return. Defaults to 20.
+   *
+   * @return \Drupal\aggregator\ItemInterface[]
+   *   An array of the feed items.
+   */
+  public function loadFeedItemsByCategory($cid, $limit = 20);
 
 }