As I said, unless there is botulism in the can, or the can’s seal is broken, it is quite safe to eat even years after the “use best by date”. That is not an “expiration date” like they put on the milk carton, it is just the date at which the company has determined the flavor of the canned food will begin to noticeably decline. Meats will still be edible for years, even decades after that date, as many experiments have shown.
As for fat going rancid, yes, it happens, which is one of the main reasons the flavor goes “off”. But though rancid fat tastes bad, it is not dangerous to eat, though it can give you a stomach ache or some issue like that.
“As I said, unless there is botulism in the can, or the can’s seal is broken, it is quite safe to eat even years after the ‘use best by date’.”
And as I said, no, it isn’t.
Survivalists should avoid rancid fats and oils at all costs.
You’re confusing the reality that eating some rancid food will typically only cause an upset stomach with the idea that your body somehow derives nutritional benefits from rancid food.
Because humans are not scavenger animals designed to live off of dead animals the way vultures and buzzards for example are, our bodies will try to reject foods that it cannot process. Rancid fats and oils that are absorbed in digestion do a lot of free radical damage and deplete the body of certain vitamins.
The point of eating is not merely to temporarily abate feelings of hunger. Our body needs nutrition to survive. Depending on a person’s body composition, the average person can go weeks with zero calories before the body goes into starvation mode. The body will first burn off junk and waste through autophagy. It will deplete glycogen reserves and draw nutrients stored in fatty tissue. Then it will begin burning fat and some muscle tissue as a protein source. Your body will be in ketosis and run mostly on fat though. When this fuel source runs low it will begin using tissue from organs, and this is when starvation kicks in and threatens to kill you.
Because your body will not get nutritional benefits from whatever is rancid (i.e. the fat and oil part of the food), it is generally better to not eat at all than to eat rancid food.
However, in an emergency, it would be reasonable to try to remove the rancid fats and oils from some foods. Nuts will almost certainly have damage to the protein and be contaminated with other threats like fungus that will kill you, so always throw out bad nuts. But meat could be boiled and drained to get rid of fat.
Bottom line is that prepping is the opposite of accepting emergency conditions as normative. Stockpiling food that is going to go bad is a very bad idea. The article presents the idea of storing canned meat as an investment, but it also points out in the article that this food expires.
You are correct that the use by date is not an expiration date, but this kind of food is not designed to be kept indefinitely. It does go bad. It may not kill you immediately in many cases, but it will kill you.
If you prefer to be stubborn about it, all I can say is I warned you. I also don’t want others here to make decisions based on bad advice. And storing canned meats (that contains fats and oils) for decades is a very bad idea.