There are Nobel prizes for discoveries about vitamin C (https://en.wikipedia.org/wiki/Albert_Szent-Gy%C3%B6rgyi). There are tons of published findings on the efficacy of this compound. There are double-blind placebo-controlled peer-reviewed proofs of how it works, that it works, why it works. It's established Chemistry fact. Yet, I've encountered allegedly-educated people who contend that vitamin C (along with all supplements) is snake oil. I once chatted with a fairly prestigious surgeon who said to me, "you know, NO supplement has EVER had ANY published findings showing it works." "Really?" I said, with a mouth-agape tone, feigning amazement at his effort to appear well-read on the absolute totality of all human research. Then I followed up, "so you stopped reading even your own journals when you graduated from med school thirty-five years ago?" To be fair, he maybe continued reading JAMA, The British Medical Journal, The Cardiologist, Cell, Nature, etc., up until the 90s. However, if you've had any interest in learning since, oh, say, 1999, you would know that your own organization changed its official stance on even multivitamin recommendations (i.e. - in favor), let alone all supplements for all time. Spoiler: science continued after the 1980s. Heck, in just the past five years there have been complete paradigm shifts in human health and the related sciences.
Vitamin C, or ascorbic acid, was actually very well understood a long time ago (about a hundred years). Its benefit to humans and a lot of creatures in the animal kingdom is evident. Though it is true that there are a couple of extremely disingenuous studies which were contrived specifically to debunk vitamin C (they purposely used a wholly insufficient and futile dosage of vitamin C versus the placebo group) while deliberately infecting humans with colds and flus, the other several thousand efforts by real scientists and researchers has indicated benefit for humans all the way up to 8,000-12,000 milligrams: www.mdpi.com/2072-6643/9/4/339.
It appears that a lot of intellectually lazy people aren't actually thinking skeptically. They just jumped on the "skeptical" bandwagon as a badge of sophistication so that they could stop reading and thinking. Dosages and saturation rates make the difference between benefit, innocuous, and deadly. It's so unbelievably simpleminded and parochial to say "doesn't work" about not just a compound we understand but ALL compounds which one terms "supplement." It's a completely throwaway sentiment with zero value. Sadly, there are a lot of studies which were conducted with the same type of dishonest parameters (laughably low dosages) for omega 3s, minerals, phytonutrients, you name it. Go ahead. Get on google. You can find a headline for anything. Guess what: alcohol and cocaine are ineffective chemicals. And you could prove that in a completely legitimate placebo-control-group study by down-dosing enough.
For those "freethinkers" in your nearby work cubicles, they're likely to scoff at this research showing benefit as well, insisting on the simpleton approach of just dismissing everything they don't already believe. But, for those of you who continue to learn, this is even more research which explores the mechanism of human health benefit from vitamin C, not just the statistical outcomes (which also happen to make a solid case for adding vitamin C supplementation):