Apparently, astronauts suffer from "food boredom," or are hypothesised to. I like the idea that someone could die from lack of variety, but only because it assumes the importance of the kind of thing often thought of today as not real. The other hypothesis given sounds more like science fiction: "their sense of smell changes as microgravity shifts fluids around in their heads."
I'm entertained by this inversion of credibility, but I think the food boredom hypothesis is believable becauses the need for variety is already pervasive. I would say it's not usually matter of life or death, but in the sense of wasted life or the nonlife implied by expressions such as "you're not really living," it is. If you live in an abundance of variety of food, eating the same thing is a little death. It is as if we try to live life in imitation of our market's plethora.
There is also a chicken-and-egg problem in this life of variety, especially if you cook for yourself. I often say I'm in a rut. It's a kind of trench warfare--all the action happens on the brief, perilous run to the next rut. At all other times the rut leads back to the rut: Making and eating repetitive food dulls the spirit, and you need to be in high spirits to even think of cooking something outside whatever rut you're in.
There's something bizarre about feeling one must always be consuming something novel. After all, the most ritualistic foods are often great pleasures. Okay, that would just be coffee and tea, for me. I know someone, though, who decided she didn't need coffee, she just needed the ritual, and began making smoothies in the morning. It doesn't matter that the preparation literally never changes, just that it solidifies into a ritual, and that it continues to convince you of its efficacy.
Efficacy is the thing, isn't it? We rush from one "ethnic" restaurant to the next because we imagine it will have more oomph than the last. We travel around the world (our own place is not a part of this world, of course) in hopes that life elsewhere is more intense than it is where we are. Travel snapshots look best with impossibly high color saturation. Memory can be sanctified if never revisited.
MFK Fisher once quarrelled with her then husband over this. He refused "to back to a place where once he had been happy." (The place was a town in France, unshockingly.) He thought it was "foolish to try to recapture happiness." She "wasn't trying to recapture anything." The two come to an equitable solution, of sorts. He can have his precious memory; she went back with her sister and had a lovely time.
This isn't a matter of knowledge versus happiness. Fisher didn't go back with the intent of ruining a beloved thing by revealing its underbelly--the investagatory renunciation of pleasure that academics (and I) get off on. It is foolish to try to make the same cup of coffee another morning. The coffee wasn't what was good. This doesn't mean one shouldn't try to make another good cup of coffee, perhaps even the same way.