No. Pokemon have eaten food that humans eat in a handful of anime episodes and did not react in any way at all (though most of those foods are fruits like cherries and apples).
Bulbapedia states that Pokemon have been seen eating rice balls and chocolate with no signs of illness (like Meowth who will eat practically anything that Jessie and James would). Pokemon can also eat things like ice cream and cookies as proven in the games by items like Casteliacones and Lava Cookies. Pokemon also seem to like honey, since if it is used out in the open, it will attract wild Pokemon.