MSN recently ran a feature about ConsumerLab.com's investigation into the purity of multivitamins. The lab looked at 21 brands of multivitamins for sale in the U.S. and Canada and found only 10 of these brands met the labeled claims or otherwise met quality standards. That doesn't have to mean anything earth-shattering. It could have been the other brands were close to meeting standards or had minor problems. However, the quality issues were ones that could actually hurt your health.
The Vitamin Shoppe Multivitamins Especially for Women were found to be contaminated with lead. Now, let's put this in perspective. Several calcium supplements run the risk of lead contamination, because lead and calcium participate in many of the same chemical reactions and are difficult to separate. That trace amounts of lead would be present might be expected. However, ConsumerLab.com reported a daily dose of this mulitvitamin contained a whopping 15.3 micrograms of lead (more than ten times the amount permitted without a warning in California). To make matters worse, though you got some bonus lead for your bucks, you only got 54% of the stated levels of calcium.
Another vitamin posed a different risk. Hero Nutritionals Yummi Bears, a kid's multivitamin, contained 216% of the labeled amount of vitamin A in the retinol form [5,400 International Units (IU)], which is considerably higher than the upper limit set by the Institute of Medicine of 2,000 IU for kids ages 1 to 3 and 3,000 IU for kids ages 4 to 8. Vitamin A is one of the vitamins where more is not better. Instead, too much vitamin A can weaken bones and cause liver damage.
Are these quality control issues? Yes, but I would have been surprised if the lab had found the vitamins met their stated claims. Why? For two reasons. First, vitamins aren't regulated by the same standards as medicine. They are considered 'supplements' and not 'drugs'. Your best defense against this is to buy a product from nationally-recognized reputable source with an interest in protecting its good name. The other reason I wouldn't expect vitamins to contain exactly what is listed on the label is simple chemistry. Vitamins, by their very nature, are reactive. The quantities listed in a product will change over the course of its shelf life. Your main protection here is to not take vitamins past their expiration date.
Should you take a multivitamin? Ask yourself whether the potential benefit outweighs the risk. If you are taking a major name brand multivitamin, you are probably getting approximately what is listed. Even then, expect some variation within the product and some degree of heavy-metal contamination with products that include minerals. These vitamins generally are safe, but don't take them automatically assuming they will help you.