Zinc to adequately boost your immune system.
As Dr. Rogers says, you don't get a single spark plug replaced when you get a tune up.
Your unsupported claim/innuendo is that he was taking adequate amounts, and that there were no other deficiencies.
"Unfortunately, many people aren’t getting the full benefits of vitamin D because they have a low level of magnesium."
https://www.lifeextension.com/magazine/2021/7/vitamin-d-magnesium-connectionEdited by MizzouTigerz at 15:43:34 on 06/29/21