[JoshMnem]

I wouldn't call the dose extremely high. Some over the counter supplement pills have 1000 IUs and it looks like the study was done with only 400 IUs. (It's over the current recommended daily intake though.)

Here is some more reading:

* Enough Is Enough: Stop Wasting Money on Vitamin and Mineral Supplements http://annals.org/aim/fullarticle/1789253/enough-enough-stop...

* Vitamin B.S. https://www.theatlantic.com/health/archive/2015/02/vitamin-b...

* Experts: Don't Waste Your Money on Multivitamins https://www.webmd.com/vitamins-and-supplements/news/20131216...

* The Case Against Multivitamins Grows Stronger https://www.npr.org/sections/health-shots/2013/12/17/2519558...

* A Scientist Debunks The 'Magic' Of Vitamins And Supplements https://www.npr.org/sections/health-shots/2013/07/23/2045251...