Subsistence is the minimum requirements for a human being to exist. Now taking in consideration Maslow’s hierarchy of needs, the most things a human needs to survive are: breathing, food, water, sex, sleep, homeostasis, and excretion.
Even though, probably a person that can only fulfill the basic physiological level is probably going to have a very miserable life.
Also as Hal mentions, food is very important and it can tell us a lot about the culture of a country. I do think that food can tell us a lot about a country, specially since I can’t define a country by the way people do homeostasis. For example: Panama is very multicultural, so the cuisine contains a bit of everything. USA has a horrible stereotype of being filled with fat people, this is mainly due to another stereotype about quantity and quality of the food they serve.
In conclusion, from all the basic things a human being needs, the one that can be analyzed the most would be food. Some people say that shelter is actually a necessary thing for people to survive, but I don’t think that’s really true. I’ve seen hobos sleeping in a sidewalk, they don’t need any shelter to survive. Besides, that’s in the second level of the hierarchy of needs, right on top of the most basic ones.