The "official" toxic upper limit of D3 is 10,000 IU/day. That change to the
upper limit was heavily fought for. Vitamin D3 experts wanted the limit lifted to 20,000 IU/day.

Vitamin D3 has been tested at 40,000 IU/day for 5 years with no negative effects.

My sister with heart disease takes 50,000 IU/day and has been taking that amount for about 10 years now.

I take 100-150,000 IU/week during winter. When I feel like I'm coming down with something I take 250,000 IU/day for 5 days.

A friend of mine's girlfriend had breast cancer. She was due for surgery in less that two months after diagnosis because they feared aggressive growth.

I recommended 100,000 IU/day until surgery. When she went for surgery, the tumor had shrunk and was encapsulated. It was removed with no problem.

I recommend anyone who is afraid of or aware of cancer in their family to maintain their vitamin D3 blood levels at 85-120 ng/mL.

Please be aware that while D3 is a powerful cancer fighter, if you allow your vitamin D3 levels to fall below optimum and cancer still exists it may rebound and become more aggressive.