I've been researching Juice Plus a bit, and Isagenix, a well-being shake-selling MLM company. When you go on the Isagenix webpage, you can see their research papers, backing up the validity of their products. A few points to bear in mind, and this is based on the assumption that a lot of these companies are similar to Isagenix-
The research project are not government or university/hospital funded. Every single paper submitted as evidence, is funded by the Isagenix company themselves
Their peer reviews are done by, you guessed it, senior members of Isagenix itself, probably paid to endorse the products
The research papers are badly written, with numerous abbreviations and spouting pseudoscience, that makes you just want to skim read to the summary ( the whole point I believe!)
The summary just basically says Isagenix is brilliant. Of course it will say this
All of the papers actually are poorly designed and unscientific, with very small sample sizes, so not valid.
It just irritates me so much that people get sucked into these schemes. My friend who does Isagenix has insisted she's done her research, but the research is so appalling, and she can't see the word for the trees