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WOW! I got a ton of replies-thanks to everyone.  The general response was that people have been using them for various lengths of time w/o ill effects (one person noted an upset stomach after three days, possibly her body getting used to the new fiber??)
As to where to get them, answers ranged from all types of health food stores, super target, jewel, krogers, on line at Gluten Free Pantry and www.everythingdelicious.com (a gf store).  Also, go to McCann's website.
As for the study,  a few people e-mailed it to me, others noted that it is available at www.celiac.com

Hope this helps others, I think I'll try them next week : )
Theresa

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