I have halted taking Vitamin E due to the dosage on the bottle stating "400 IU" I have been reading that a normal daily dosage for an adult is around 15 to 22 IU daily. If this is true how come the IU dosage is as high as it is?

I started taking vitamin C and will be taking ALA shortly. I also contacted a local health store that can order a few items for detox and they also have a free mercury testing kit. Probably wouldn't hurt to recheck to see what levels I have more mercury.