If so, the phrase of the day is “buyer beware.” The supplement industry is essentially unregulated, which means that manufacturers do not have to show proof of their product’s safety or efficacy to take it to market.
There are some ethical, reputable manufacturers, and, unfortunately, many that are not so. Your best bet is to stick with a standard multivitamin and mineral supplement that contains no more than 100% of the daily value for any recognized nutrient—information that should appear on every package on the supplement facts panel.
Contrary to popular belief, getting more than 100% of your daily needs for vitamins and minerals through supplements does not provide greater benefit, and in some cases, can cause unpleasant or serious side effects. Specific populations may benefit from individual supplements, but talk to your physician and/or a registered dietitian before you spend your hard-earned money on any of them.