Unfortunately, the science isn't always easy to get at. Most studies are just someone paying for a very specific result, then sending a very carefully-worded press release to the media so they'll all parrot those exact same carefully chosen words. Press releases don't always have links to the source, and the source isn't always online. Sometimes you have to make calls to find out what was studied and how, sometimes it's not available at all. Often it takes months for the scientific community at large to actually get their hands on a study, and meanwhile the public read the press release and took it as fact long ago.

There are facts in every study and more legitimate-in-general studies out there, but with so many billions of dollars in the industry, there are just way too many fingers in the pie. One study will overstate the dangers of a substance to sell diet pills and supplements and competing products, and another will understate them to keep selling the product. A study might find a 0.01 disease rate in a group that doesn't use a product, and a 0.02 rate in those that do. If your funders are supporting it? No statistically significant difference. If your funders want bad news? This product doubles your risks of disease! It gets so tiresome trying to filter out what is or isn't crap, especially when science is still advancing and our understanding of the issue in general is steadily changing.

This is a bit over dramatic. Notwithstanding the studies funded by lobby groups, a lot of studies are done by university researchers and published in peer-reviewed journals. While these journals may require a subscription to access, they are generally easily available to anyone with access to a university library. No problems for the scientific community there.

The studies, yes. The reason for the drama is that very few people base their decisions on the studies; they either just don't know about them, or don't read them because they're boring, as dry descriptions of statistical anolysis are not high on most people's lists of things to read. They hear the story about the study, which is whatever the people funding it want it to be about. Or they don't hear about it at all if nobody reports it, since even if it's open to the public, "hey everybody let's take a trip to the university library to read 50 pages of results about how a lab fungus reacted the same way to being poked with various things, and maybe other stuff that was researched recently!" is not a thing you hear people say often and/or ever.

The C in Vitamin C stands for citrus fruits (in which it was first discovered and which have an abnormally high concentration of it) but nothing else really. It's sometimes called L-ascorbate or L-ascorbic acid. And in tests, it's been reported by cancer patients who took daily doses of Vitamin C that it actually helped them have more energy, better appetites and decreased pain etc. Also, they are looking into how Vitamin C could be used in conjunction with chemotherapy to make it more effective; thus it will take less of a toll on the patients. http://www.sunridgemedical.com/treatments/vitamin-c-and-cancer So no, you won't get cancer from fruit juice.