How much Vitamin D are you taking? I have been supplementing with it, but it did not put much of a dent in my winter depression. And what is considered to be a loading dose?
10,000 IU per day. A loading dose is in the range of 100,000IU to 1,000,000IU, depending on age and body weight. Hypervitaminosis D only occurs when you take a loading dose level for months or years; it's not possible to acutely overdose on vitamin D.
That's a lot. Vitamin D tests are easy to get, so I just took a few over a few months to find a dose that would keep me at ~50ng/ml. Previous to that, I had taken 5000+ IU/day for some time and the test showed my levels were very high.