Help setting up a sql query

Ok, if i understand you clearly, then this is the solution

// first get the post ids that have the breakfast food type
$post_ids = $wpdb->get_col( "SELECT DISTINCT post_id FROM $wpdb->postmeta WHERE meta_key = 'type' AND meta_value="Breakfast"" );

// now get the food names
$stocktypes = $wpdb->get_col( "SELECT DISTINCT meta_value FROM $wpdb->postmeta WHERE meta_key = 'food' AND post_id IN (". implode(',', array_map('absint', $post_ids) ) .")" );


if ($stocktypes) {
    foreach ($stocktypes as $stocktype) {
        echo "<option value=\"" . $stocktype . "\">" . $stocktype . "</option>";
    }
}