I think you can be sure that Dr de Meirleir has no valid evidence on which to base his comments to you. He frequently makes statements without valid evidence it seems. As a physician I do not see how he can know what he has told you. You are right to be sceptical. This is not real medicine as far as I know. As you know, I am all in favour of new treatments and have developed them myself, but based on carefully gathered evidence. There is no reliable published evidence that I am aware of on 'leaky gut' in CFS or a proven means of treating it.