Why is retinol (a form of vitamin A) toxic when taken in excessive amounts?
The same reason every chemical, including water (dihydrogen monoxide), is toxic when taken in excessive amounts. Your body can only break down (or metabolize) so much of certain substances at a time. Anything in excess, even exercise and good food, isn’t good for you. The specific answer to your question, though, is that hypervitaminosis simply overloads your liver and you die from poisoning. The same way alcohol poisoning is caused my too much drinking of alcohol and hyperhydration is caused by too much drinking of water. Eating too much liver or taking too many supplements/vitamin pills is the only way I could think of overdosing on vitamin A. So don’t do that. Also, studies show that, over time, too much retinol can cause osteoporosis (decrease in bone density).
