Why do certain vegetables make me sick? I tried to eat Celery and broccoli the other day and almost vomited. Then i tried to eat boiled Pak Choi, peas and baby corn and it just didn't go down. This also happens with boiled carrot and onion. The only vegatables i can eat are fresh tomatoes, carrots, lettuce and fresh onion. If i force myself to eat anything else i feel really sick and feel like i need to vomit.