To be honest we don't see an abundant of cases at our hospital. And if we do the majority of them are women on the women's floor which, I obviously do not cover
What I have garnered thus far:
Some literature states that Calcium glycerophosphatates may be useful in treating IC pain. A similar study reports baking soda (or a similar base) may reduce diet related IC symptoms, especially if acidic foods trigger pain.
A Moldwin (MD) and Shorter (RD) article in the Journal of Urology states that >90% of IC sufferers claim there is a definitive nutritional component that triggers their symptoms.
The food items that topped the list?...
Coffee, tea, soda, alcohol, and citrus juies (including cranberry juice). Foods and drinks with the artificial sweeteners aspartame and saccharin (splenda, monk fruit and Truvia may be ok).
Hot peppers and spicy foods. Horseradish, vinegar, pineapple and tomatoes.
She should (if she hasn't already) attempt an elimination diet to find her specific triggers... ie. eliminate all of the above, and then reintroduce each item, one by one, to see if it causes any symptoms.
Since IC is an inflammatory condition (ends in -itis) and is seemingly of unknown etiology, I dont see why anti-inflammatory neutraceuticals such as high potency omega-3 fatty acids may be beneficial. Ideally more EPA than DHA.
Some sites/articles that may help:http://www.ncbi.nlm.nih.gov/m/pubmed/17499305/http://www.ichelp.org
Allergies may also have an effect on interstitial cystitis, however, immunology is not my strong subject. I defer to the doc or someone else for that.