According to an article by the Mayo Clinic, vitamin D may not actually be as toxic as was once believed: Vitamin D Is Not as Toxic as Was Once Thought: A Historical and an Up-to-Date Perspective

In the 1940s, vitamin D was used for rheumatoid arthritis. But, the amounts being used were between 200,000 and 300,000 IUs of vitamin D. The reason this could have helped is that vitamin D helps support the immune system and helps lower inflammation. 

In the 1950’s they were fortifying products like dairy products with vitamin D. But, there were some complaints from parents with children who had side effects. The fortification of vitamin D in dairy was banned in Europe, but not in some other countries, including America. 

Years later, it was discovered that these children might have experienced these side effects due to a rare genetic disease called Williams syndrome. With Williams syndrome, you don’t actually want to take vitamin D at all. 

Now, when you look at vitamin D, it always says something along the line of “don’t take too much, you could experience a toxic effect.” 

But, according to this article by the Mayo Clinic, it would take getting 50,000 to 100,000 IUs of vitamin D for months to years before vitamin D would become toxic. This is actually a lot more than what most people consider toxic. …

Vitamin D Toxicity: Is This a Danger?

May 19, 2020