http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1966574/pdf/brmedj02907-0037.pdf Low steroid hormones can be a factor or directly the cause in malabsorption/leaky gut for some. I find this especially interesting since my 17-ketosteroid urine panel came back very defficient. This is most intriguing in the context of CFS, since is well established that some form of HPA dysfunction is happening, normally found in tests as hypocortisolism. Now, when trying to fix your gut problems caused by HPA dysfunction (affecting thyroid and adrenals) is a bit of a catch 22 since you need certain nutrients etc to be taken, and oral are the most readily available. Having the GI compromissed after years of oxidative/nitrosative stress, hormonal decay and chronic inflammation oral supplementation seems not the best. So, the best is either sublingual or IV. Or micellized. Tying this with methylation, some people have found that methyation treatment greatly improved gut. This could be due to it gradually restoring glutathione which while depleted was causing the HPA misfiring. Not only that but both b12 http://annals.org/article.aspx?articleid=688366 and folate http://annals.org/article.aspx?articleID=686628 can cause and reverse leaky gut/malabsorption. Their defficiency can, however, be the consequence of malabsorption too. Is good to have in mind all possibilities since is well known that we are all different. Personally I think both adrenal, thyroid, gut and methylation treatment together should give the best outcome but doing all these at the same time means an amount of monthly expense that someone "chronically" ill rarely can afford. So is matter of everyone discovering what is the most dysfunctional system for them and start with that.