Interesting article about the dangers of supplements.
Two takeaways:
1. Always keep in mind that these supplements are not regulated. They do not need to prove that they are safe OR effective before hitting the shelves.
2. Something that seems "natural" (like green tea extract) is not by definition good for you or safe. There is nothing natural about drinking a gazillion cups of tea (or consuming the equivalent amount in a pill).
NYTimes article on supplement safety