Hello, Palash:
Regret SOME ice cream contains terrible forms of starch like tapioca, especially in hotter climates it helps the dessert maintain its consistency. ALWAYS TEST WITH IODINE--it is so easy to just bring a small bottle with You!!! Food is too often adulterated--especially prepared or outside foods; BE AWARE.
is it not possible to avoid this iritis for life with NSD?
I have only avoided iritis for 15 years using NSD/antibiotics. Once, when I cheated on a lengthy airplane ride, I resorted to antibiotics when incipient symptoms of this terrible aspect of AS began. Fortunately, it worked quite well. But IRITIS in particular has kept me on the straight-and-narrow, with respect to diet!
Hope You sort this out and buy some more ice cream but TEST FIRST! Then give the culprit a piece of Your mind...somewhat gently; 'they know not what they do!'
HEALTH,
John