We laugh at the quaintness of the snake oil salesman or yore -- but he never left, not really. ==== Edit ==== Not calling Pauling a snake oil salesman :-)
When I Googled "synthetic vitamin C carcinogenic" I found a bunch of quackery and the Scientific American article. Mostly the sites were screaming "IT'S A CHEMICAL!! CHEMICALS ARE BAD!!!!" as if water and foods aren't also made up of chemicals... :|
[1] http://blogs.scientificamerican.com/guest-blog/natural-vs-sy...
Not to do with synthetic vitamins, of course, but certainly to do with the selling of vitamins as something you need to supplement.
Here's my reference: [1] Key Quote:
>One of the largest, longest, and most carefully conducted human trials on multivitamins, the Physicians’ Health Study II, showed that the daily consumption of these supplements over 11 years reduced total cancer incidence by 8%, better than any pharmaceutical drug to date. This could translate into 130,000 fewer cancer cases in the U.S. every year.
[1] http://lpi.oregonstate.edu/feature-story/vitamins-do-not-cau...
2. One of the whole arguments against supplements (which is what we're talking about here, not the quantities found in an every-day diet) is that they tend to mega-dose. But not "mega-dose" in some scary, doping type way. The vast majority of bottles of supplements list RDA values of 200%-1000%, as if that's a good thing.
3. The studies that show cancer link do so with double-blind, placebo-controlled studies using normal, grocery-store supplement levels of antioxidants. e.g. http://www.nejm.org/doi/full/10.1056/NEJM199404143301501, http://jama.jamanetwork.com/article.aspx?articleid=1104493
4. When you look at reviews that are not pushed by the Linus Pauling Institute, you get quotes like
> A recent review of the last 20 years of literature on the subject, presented at the American Association for Cancer Research 2015 meeting, found an overall increased risk of cancer among vitamin users.
https://www.sciencebasedmedicine.org/vitamins-and-cancer-ris...