The thing about research is that if you look for studies to support a particular conclusion, you can always find them, usually more than one. You could probably find a study or two to support eating nothing but beef and pork, if you tried hard enough. But if you want the truth, you have to read ALL the related studies, and you have to critique and interpret them and understand their scope/limitations and relate them all together to build up as complete a picture as you can. Dr. Greger isn't perfect, but he and his team seem to be doing a hell of a job trying to find the truth.
He advocates a whole-food plant-based diet because overall, that's what the evidence seems to say is healthiest. But he's not a hard-line vegan or anything, just trying to ensure that people have can make informed choices by giving us all the information. Not just in terms of broad strokes like "eat more vegetables, don't eat so much meat", but all sorts of weird and interesting details like which sorts of lentils are healthiest, or why broccoli sprouts are amazing at fighting cancer.
And it's not an alarmist site -- here's a nuanced take on glyphsate, used on GMO soy https://nutritionfacts.org/video/gmo-soy-and-breast-cancer/
Back to the topic at hand, here's an example about Soy and prostate cancer. https://nutritionfacts.org/video/the-role-of-soy-foods-in-pr...
And to find a way out of the forest of conflicting info -- if you find a study and want to get a second opinion on it, search for it on nutrition facts (you probably have to use google, with a query like "site:nutritionfacts.org <study keywords>").
I'm not encouraging you to blindly believe what Dr. Greger says! You should evaluate it for yourself. But I strongly believe that after watching a few videos on random topics, you'll start to see how most people have no idea what they're talking about when it comes to nutrition science, and intentionally or unintentionally spread falsehoods.
