Your article has failed to mention the single most important benefit lemon juice presents and that is to acidify your stomach so that you process food easier. As we get older our stomach acids are not as powerful as they used to be so drinking a little lemon juice kind of kick starts your system. 
Apple cider vinegar is also very effective at doing this and is a little stronger the lemon juice. They both highly recommended by naturopaths . It's amazing how the main benefit is completely unknown to most people.