It's unbelievable crazy what the author suggests, even say "10,000 IU if you're feeling daring / have darker skin / live in less sunny climates.".
Just a simple look at the side effects of high dosages:
Safety and side effects
Taken in typical doses, vitamin D is thought to be mainly safe.
But taking too much vitamin D in the form of supplements can be harmful and even deadly. Taking more than 4,000 IU a day of vitamin D might cause:
Upset stomach and vomiting.
Weight loss and not wanting to eat.
Muscle weakness.
Not being able to think clearly or quickly.
Heart rhythm issues.
Kidney stones and kidney damage.
Just a simple look at the side effects of high dosages:
Safety and side effects
Taken in typical doses, vitamin D is thought to be mainly safe.
But taking too much vitamin D in the form of supplements can be harmful and even deadly. Taking more than 4,000 IU a day of vitamin D might cause:
https://www.mayoclinic.org/drugs-supplements-vitamin-d/art-2...