I admit I didn't make that clear, the point was 5k UI is not healthy to take long term. But you build a supplement regime around it, and then just keep taking it for years. That's how easy it is.

And in another thread a guy was saying his daily D3 was 20,000 IU a day as if it was perfectly normal.

I was found to be extremely deficient in a blood test and personally been prescribed 10k UI, or maybe even 50k I can't remember, but it was a weekly tablet for only 6 weeks.