There are studies on it 50/50 as in 50 swing one way, 50 swing the other. There is nothing yet that is SOLID like you would find for creatine studies.
My suggestion is to not worry about it unless it comes in a supplement you use. There is some in mine, but the product I use I do not use it because of it. It just happened to be added.
The boards here are not usually places people talk TONS about supps. bb.com is better to get all nitty gritty.
Most people will tell you that they will do you no good if your training isn't there nor your food intake, rest, etc etc.
So first and foremost, make sure ALL of the above is set. I think supplements are great and many advancements in them and what not, and I love the industry, but what I DO NOT LIKE is when people JUST start lifting and then they ask about supplements.
Now I dont mean you, I just mean the kid who goes... What supp stack should I take and it is his first day in the gym.
You should have a solid routine down, diet down, your rest, and everything else figured out and IMO done for a bit before you start taking supplements.
What happens is too many younger people, and people in general RELY on them. They are supplements. Look up the word. They are to SUPPLEMENT everything and not TAKE PLACE OF.
I know people who take all sorts of crap and say they take NO XPLODE and this and that, and they STILL look like crap or are partially fat or weak or what ever.
Just cause you take a supplement doesn't mean it is a cure all.
Anyway, just some info