Vitamin D is extremely cheap, so I assume it is very easy to manufacture. It's also freely available in a lot of different stores. So I doubt there would really

Vitamin D is extremely cheap, so I assume it is very easy to manufacture. It's also freely available in a lot of different stores. So I doubt there would really be a shortage. Additional data point: In Belgium, it's encouraged to give your children daily Vitamin D supplements until the age of 6. That tells me that there is scientific consensus about the safety, and that there is a large supply of it.