Bring some SEALED bars from home to eat. If you can eat cereal, there are boxes of cereal on the breakfast buffet you can grab. Or sealed nuts they sell in the shops (expensive, so bring from home). Anything that is sealed will be allowed.
I noticed on my last carnival conquest cruise, they really screened in the ports this time. Purses were even opened and examined. I dont remember seeing them make women open their purses until this last time. I read on this or that forum that people managed to sneak food into the ports that was against the law and not respecting that country's laws. If you really need to not eat the local food, bring your own and make sure it is sealed. I have eaten local food even off carts and never gotten sick. Other than a box of cereal for emergencies if I have a long excursion, I eat the local food.
Most ports its the law .. its not up to Carnival .. its the law to protect their enviroment. If you are really picky about what you can and cannot eat.. I would bring some bars from home as I said. Some sealed snacks, and plan ahead.
Conquest 7/21/13, Miracle ALASKA 8/27/13, Miracle HAWAII 9/17/13, Celebrity Summit, 11/30/13, Celebrity Summit, 12/7/13, Celebrity Constellation, 2/7/14, NCL Epic 3/2/14, Allure 5/4/14, Allure 11/2/14, Quantum 12/8/14