Michael Savage (The Savage Nation-November 7, 2014 broadcast) comments that when he is not feeling well he boosts his immune system by taking vitamin C, vitamin A or retinol, and zinc; among other supplements.

The Savage Nation

Minutes 16:46 through 17:11 of the following full video.

This dosage is ONLY for when you are sick. Taking such a high dosage on a daily basis is neither safe, nor recommended. As Michael stated, he takes this dosage for ONLY one or two days in a row when he is feeling sick.

WARNING: Chronic, or daily, high dosing with Vitamin A or retinol can be toxic to the liver.