It actually isn’t. 400 IU is based on preventing disease. To obtain optimal health though, dosages should usually be much higher. Obviously this differs from pe

It actually isn’t. 400 IU is based on preventing disease. To obtain optimal health though, dosages should usually be much higher. Obviously this differs from person to person, but 2000 IU should lead to optimal vitamin D levels. This is an interesting video on the topic: https://www.youtube.com/watch?v=jeLC_b5gDUM https://www.youtube.com/watch?v=jeLC_b5gDUM