Unless they deliberately intercept shipments in the warehouse and secretly poison them the way they did with Tryptophan, there is no way to keep people away from Vitamin-D supplementation.
The need for this vitamin during long term shelter stays cannot be understated. There are many ways to acquire it in substantial doses, but I recommend storing the capsules if nothing else.
I don't expect you to wade through a thousand .PDFs the way I do in any given week on the subject, so you'll just have to take my word for it. Vitamin-D is a miracle substance. No, really. Not like a testimonial. It really is a miracle substance. It makes so much sense in evolutionary terms for us to derive so much of our healthy metabolic function from this vitamin since we make it for free from the Sun and get lots of it in fish. It's always been available as an enzyme, no matter where we were at the time in our history.
You should always be ready for the counter-propaganda push. The pharmaceuticals companies are going to pour millions and millions of dollars into their lackey research institutions over coming years to try to confuse, obfuscate and discredit all this research over the past thirty years, but it's become an unstoppable tsunami of information.