It’s not easy to answer this question.
If we only take a look at the daily recommendations we can see that governmental agencies can’t even agree on it either.
For example the daily recommended dose (RDA) just recently has been increased from 200 IU to 600 IU. It might not seem much but that’s a 300% increase. This proves Vitamin D has a major role in our body.
Not long ago it was considered 1000 IU a day is too much. Now some say 5000 IU and others consider 10,000 IU too much. Nobody can tell you for certain.
ISERT HOLICK CHART
I’ve found this interesting study. On the vertical axis you can see the D3 levels in the blood. From 0 up to 1,800 nmol/L. To put this scale in perspective the average American has a blood serum level is 62-67 nmol/. It is considered high deficiency if someone is below the 50 nmol/L.
The Hadza tribe in Africa has the highest D3 levels in any nation. Their level reaches 287 nmol/L.
On the horizontal axis the amount of vitamin D they were given on a daily basis. Yes you can see it right. There were some subjects who were taking a few millions of IU a day.
According to Dr. Holick you won’t have too much if you keep this simple guideline. Limit your daily intake below 30,000 IU. And have your blood serum level below 500 nmol/L.
Vitamin D it is as safe as it can be. There’s a huge gap between estimated dosage and toxicity.
From all this data it is safe to suggest that taking a few thousands of IU a day will not be too much.