These are the basics like milk, bread, tatties and pasta, especially if you're a carb lover like me.
And come December, there's something else that no person is able to survive without.
Here's a clue: you'll find it through the seven levels of the candy cane forest, through the sea of swirly twirly gum drops, and through the Lincoln Tunnel.
Yes. It's obviously Elf.
The best Christmas film to come out of Hollywood and arguably starring the best character in the world of movies ever.
There is the Muppet Christmas Carol debate, of course, because the Muppets are always a firm favourite. But, listen, they both have their time and place.
Elf has to top the list for it's fabulousness and originality. Just. And Dickens gets enough praise really. There are several reasons why Elf is so watchable.
I have the attention span of a goldfish and usually switch off half way through films.
In fact, I still think the ending to the film version of Dan Brown's thriller Angels and Demons is when Ewan McGregor's character parachutes into St Peter's Square.
(FYI: that's about a third of the way through.)
But when Elf comes on I manage to sit still through the whole 97 minutes - including the adverts - in awe of Will Ferrell's wonderfully daft Buddy, who brings joy to even the dullest of households.
"SANTA! OH MY GOD! SANTA'S COMING! I KNOW HIM! I KNOW HIM," shouts Buddy in the department store.
You have probably been hearing that a lot recently - and not only from children. And me.
That's because there's a bit of Elf in all of us.
My friend Lauren is actually Elf - she can eat more chocolate than humanly possible, openly belches and dances like Buddy in the mailroom scene. And she has never forgiven me after I forgot to buy syrup for her roll.
The other day I halted my gift-buying trip to find a copy of Elf on DVD. It became a mission for my sister and I who decided Monday night viewing wasn't complete without a trip to Elf's world.
You can imagine how much we laughed when we came back to my flat to find a copy of the film already on my shelf.
But, you see, Elf is like a pint of milk. You buy it "just in case".
Still, I was saddened to find out that Channel 4's annual Sunday afternoon showing of Elf was absent this year. It usually takes place on the second Sunday of December and in 2008, pulled in more than six million viewers
Apparently only Sky Movie customers can watch it on TV, after they bought the rights.
In the true spirit of Elf I won't be going in a huff...however, I'm here for anyone else so if you need a copy, let me know. I have two.