Disturbing Articles on Inulin

I saw on t.v. that inulin is still being used in some dietary "fiber" supplements. This article [Ma et al., 1991: (http://www.ncbi.nlm.nih.gov/pubmed/2035637)] shows that inulin actually can be absorbed through the intestinal tract intact, and that's really disturbing. Inulin is used in animal research to evaluate kidney function, among other applications, but it distributes to the extracellular fluid by some kind of bizarre interaction with albumin. It tends to distribute extracellularly and to influence the intravascular and extravascular fluid balance by that effect. I think it's similar to the effect that a disturbance in the serum albumin-to-globulin ratio can have on the extracellular fluid volume, as in ascites in liver disease (as in a "positive albumin gradient"). I've seen inulin used for all sorts of applications like that in animal research, for "labeling" the extravascular compartment, etc. To the extent that inulin could be absorbed, it could potentially cause hyperosmotic stress and disturb endothelial cell barrier functions in the blood vessels. I don't want to think about what could conceivably happen at the blood-brain barrier or blood-CSF barrier.

Inulin has a molecular weight of ~5,500 Da, and the traditional rule is that substances with that high molecular weights are not absorbed into the blood intact and cannot cross the intestinal barrier. But the authors discuss the compact quality of the inulin molecule and suggest that it can simply be absorbed by the paracellular pathway, by diffusing between the epithelial cells. Consistent with its potential for creating osmotic disturbances, Ten Bruggencate et al. (2006) [Ten Bruggencate, 2006: (http://jn.nutrition.org/cgi/content/full/136/1/70) (http://www.ncbi.nlm.nih.gov/pubmed/16365061?dopt=Abstract)] found that inulin disrupted intestinal barrier function in humans. That first article I cited (Ma et al., 1991), in particular, is very disturbing to see, given that some products contain inulin. That molecular weight, 5,500 Da, is much lower than the molecular weights of most other so-called dietary fibers or cellulose-based grains, etc., and the low molecular weight, as discussed by Ma et al. (1991), are a significant determinant of the capacity for a non-degradable substance to be absorbed. Gay-Crosier et al. (2000) [Gay-Crosier et al., 2000: (http://www.ncbi.nlm.nih.gov/pubmed/10798950)] found that inulin caused anaphylactic reactions, severe allergic reactions, in some people. Sounds fantastic.