Which food additives are most concerning in Crohn's?

In general:

sodium nitrate

saccharin (US, not allowed in Canada)

caffeine

olestra (US, not allowed in Canada), calorie-free fat substitute

acesulfame-potassium (also known as acesulfame-K), artifical sweetner

artificial colouring

salt

sugar

Especially in Crohn's Disease:

• polysorbate 80 (nonemolient surfuctant, emulsifier)  [read more at my post here]  It is known to promote translocation of e-coli into ...
• carrageenan, sulphated polysaccharide used as gelatin (Vegan, Vegetarian diets), thickner, stabilizer, emulsifier  [read more at my post here]

Food additives permitted for use in Canada

Guidelines for the Use of Food Additives and/or Processing Aids Intended for Fresh Fruits and Vegetable

Food additives: The good and the bug at C-Health