i just came across this recent study on mineral oil for the treatment of chronic constipation. http://cpj.sagepub.com/cgi/content/abstract/45/9/856
Here's the title incase the link doesn't work for you.
The Safety of Mineral Oil in the Treatment of Constipation—A Lesson from Prolonged Overdose Clinical Pediatrics, Vol. 45, No. 9, 856-858 (2006)
Basically the artcile states,
"Summary: There have been concerns regarding the interference in the absorption of fat-soluble vitamins in long-term treatment with mineral oil; however, there is no clear evidence in the literature to support this claim. We present a case report illustrating the effect of prolonged (5 months) large doses of mineral oil on the fat-soluble vitamin absorption in a 17-year-old girl......Our case would support the position that even massive overdosage of mineral oil for a period as long as 5 months does not have any significant impact on vitamin ADEK levels in an adolescent. Taken together with previous studies results supports the safety of mineral oil in regular doses. This observation does not necessarily exclude the possibility that in smaller, rapidly growing children, a prolonged overdose of mineral oil might be detrimental."