Did my masters on Vitamin D - It is very difficult to extract CLINICALLY RELEVANT information from retrospective epidemiological studies.
However, there a a few things that are clear:
1. Calcium absorption from the intestine increases with vitamin D supplementation dose up to around 8-10,000 IU D3 daily.
2. 15 minutes of full body exposure in noon sun is equivalent to a dose of ~20,000 IU D3
3. There are few cases of vitamin D overdose in the literature - doses in the 1,000,000 IU+ range within days is generally where symptoms are noted - this excludes people with kidney disorders.
Personally, I take 10k IU D3 a day. The D3 is important because D2 has 1/2 to 1/3 the effect per dose in raising calcium absorption levels.
I would recommend this level of supplementation to anyone who doesn’t have a kidney disorder.
However, there a a few things that are clear:
1. Calcium absorption from the intestine increases with vitamin D supplementation dose up to around 8-10,000 IU D3 daily.
2. 15 minutes of full body exposure in noon sun is equivalent to a dose of ~20,000 IU D3
3. There are few cases of vitamin D overdose in the literature - doses in the 1,000,000 IU+ range within days is generally where symptoms are noted - this excludes people with kidney disorders.
Personally, I take 10k IU D3 a day. The D3 is important because D2 has 1/2 to 1/3 the effect per dose in raising calcium absorption levels.
I would recommend this level of supplementation to anyone who doesn’t have a kidney disorder.