“A good daily supplement to boost the immune system is Resveratrol.”
Agreed. Been taking it (and others) for ~15 years. Generally, fewer issues (particularly infectious diseases) than most my age.
For ingesting higher doses without a Montezuma outcome, check into liposomal Vit C. You can also get a Dr to give high doses intravenously if you can find one to do it.
It really works. I've only been taking it on a daily basis for 5 years or so. I told an acquaintance about it who said he gets sick all time calling himself a "bubble boy". Saw him a month or two later and he said he's felt great since he started taking it daily. Two years later; same thing so it does work. One 1000mg a day. I was taking 2000mg a day but adjusted it down to 1000mg about a year ago. Still works good but ironically I currently have a stubborn head cold that's going around.