All of these are available at the supermarket however I have brought canned tuna fish every time I've come down and they have never bothered me. They have definite seen them because I alway have a lot to declare and they go through my bags. The worst that can happen is that they take it away from you. Relax, pack it, say nothing and if and only if they question it, tell them you are on a special diet and smile.
The embassy probably didn't answer because they are still laughing over the question.
Have a good vacation and please relax. I've always found the customs people very reasonable. Beside that there probably is not an answer to your question. It will depend on who is the customs officer that day but I would bet you will not be bothered.