Dear lilypaws - You can take all the guesswork out of purchasing supplements - I have posted this link here many times and they allow it. Consumerlab.com is a consumer watchdog group for supplements; they test for purity, strength, and such things as whether or not they open up in the body. I once spent $80 for some turmeric that would NOT open up - not even in a glass of water or a glass of vinegar for two days! There is a fee for their service which helps to fund the work - but it is not too much considering the money they can save you on a lousy supplement. For instance, many people are surprised to learn that AlgeaCal has too much lead in it and it only contains 87% of the magnesium it claims to have! The address is http://www.consumerlab.com. They also have hundreds and hundreds of articles about different supplements and what they do for your body. I've been a member for a decade and I consider it money well spent.