I just heard from someone I hadn't spoken to in a long while. Apparently, her doctor had dx her as having low vitamin D levels and prescribed supplements. Not long after, she became violently ill. So ill, she had to be hospitalized and her doctors thought she was dying. It didn't occur to them to test for Vitamin D toxicity because she had been taking the supplements for such a short time. When the finally did, her levels weren't really that much higher than what might be considered a "high normal." They stopped the supplementation anyway and her health began to steadily improve. Now, I'm pretty sure this is an atypical response. Her reaction to Vitamin D and what constituted "toxicity" for her individual makeup appears to be different than the average person. I don't know what her levels were when she started. I don't know what her levels were when she became ill. All I'm saying is that apparently, it's possible to have a toxic reaction to supplementation even if you are not taking mega-doses of your supplement of choice. Be careful out there. In my own case, Vitamin D supplements made my heart palpitations much worse than normal, and I had to quit supplementing.