Save XElement without affecting the current header

So, I'm loading the XElement of a document like this:

Root = XElement.Load(Path);

The original header looks like this:

<?xml version="1.0" encoding="iso-8859-1"?>
<!--Some comment -->

When I call Root.Save("file.xml"); it changes the header declaration and erases the comment. Why is this happening? What can I do besides creating a new whole xml with XDocument to avoid this?