Dr. Berg's vitamin D is rat poison? Dr. Berg uses synthetic lab-made D3, which is basically rat poison. Not kidding, it's actually toxic for the body. That's completely false. My vitamin D is not synthetic. It's from sheep wool. That's what they use as a natural vitamin D. But it is true that high doses of vitamin D can be toxic to a rat. But they would have to consume 150,000 IUs of vitamin D3. Humans are much less sensitive to the toxicity of vitamin D. The toxic level of vitamin D3 for someone who is 70 kilograms or 154 pounds would be 5,600,000 IUs, 560 times more than what I recommend, which is 10,000 IUs per day. Or you would have to consume 4.5 bottles of vitamin D3 in one sitting. So no, the daily doses of this is absolutely safe.