One with their priorities in the right place is Consumer Lab, a privately owned testing company. Consumer Lab has found that, on average, about 25 percent of the nutritional supplements fail to meet their own claims of safety and ingredient integrity. Some don't meet labeling requirements, some don't contain what they claim to, some products are contaminated, while still others don't dissolve properly. Consumer Lab also provides "one of the best science-based encyclopedias" of vitamins, minerals, supplements and herbs accompanied by drug interaction and side effect precautions.
Nutritional supplements are worth a look. If you find yourself intrigued by one, research the facts put out there by several sources. Do not depend on manufacturer's explanations and studies. Go to reliable websites before you shell out the big bucks for something the Food and Drug Administration (FDA) has only evaluated as a food.