Brussels Airport offers possibly the worst food choices of any airport through which this reviewer has ever passed.
Vegans will have to bring their own food, as there isn’t anything on any menu suitable for that diet. Vegans can purchase nuts in Duty Free and some vegan crackers. None of the salads were vegan.
Vegetarians can buy an overpriced tomato and mozzarella baguette or a slice of Pizza Hut pizza with only cheese and tomato for €3.60, or the whole pizza for a whopping €19.95. Pizza Hut cannot make a pizza without cheese and lacks basic ingredients such as mushrooms and olives.
Once beyond security there are even fewer choices, with nothing for vegans and just some pastries for vegetarians. Water comes in at €3.30 per 0.5l for still and €3.60 per 0.5l for sparkling, though vending machines sell the same amount for €2.50. Note that there is a water fountain outside the toilets, though you don’t know whose mouth has been in contact with the tap, as some are witnessed to do. Selling water at that price seems radically unjust given regulations which bound one to purchase water and prohibit one from bringing one’s own water (or an empty bottle for the water fountain) through security.
In short, bring your own food.