N-A-G is a supplement you can get in health food stores, or on-line. I've not heard it being used for strictures. It's my understanding it may help decrease symptoms of IBD (may help protect the gut lining) and osteoarthritis. I've taken it for about
a year now, but I'm on a number of other supplements and meds, so ... who knows. Here's more info:
http://www.webmd.com/vitamins-supplements/ingredientmono-619-N-ACETYL%20GLUCOSAMINE.aspx?activeIngredientId=619&activeIngredientName=N-ACETYL%20GLUCOSAMINE.