Unfortunately, the food supplement business is a billion dollar business that goes unregulated. Noone checks to make sure they are what they claim they are, and unfortunately ppl take advantage to join the billion dollar business.
My mother uses a lot of supplements. I had a friend of mine who was a pharmacist check what was in the bottle of some "natural cold remedy" sold that my mother was using. It was basically all "filler" in the capsule.
I'm sure there are some good ones out there who do contain what they say they contain; however, I'm always skeptical.
