Here is a link to foods and their analysis
Caudata Culture Articles - Nutritional Values
Raw meats are not bad for axolotls, but still should not be staple diet. From what I have heard its more like raw meat is more of a treat, then a diet as some pets(not just axolotls) will start to turn down their normal food because of how good the raw meat is. But other then that have heard more horror stories about feeder fish and shrimp and snails being eaten then raw meat.
I hope this link helps you guys out with this discussion.
Though 7 years is not long to have an axolotl, it is not unusual expecially if you had them 5-10years ago as the information has changed. I met someone who bought an axolotl from me and she had one about 10years ago that died at 7 years old. After talking to her a bit more realized it wasn't negligence or improper care, just the amount of research on axolotl care and disease etc has changed over the years. She was doing research before getting the juvies fromme and told me how much different their care requirements were! It was actually interesting to sit down and talk with her about it as i have only had axolotls were just over a year