Cancer patients and survivors should discuss supplement and vitamin use with their oncologists.
The Food and Drug Administration treats dietary supplements more like food than drugs. This means that the standards the agency applies to medicines, including testing of products before they are put on the market, don’t apply to supplements. There is also no defined standard for many commonly used terms, such as “natural,” which means that consumers are often left to choose supplements based on the label—with no guarantee that what’s on the label is actually in the bottle.
Buyer, beware. Do some homework before buying supplements. For example, the service Consumerlab.com runs independent tests of common vitamins and herbs, searching for purity, amount of active ingredient and contaminants. Some results have been surprising—revealing several times more or less of the ingredients listed on the label, or contamination with metals and other substances. As a case in point, recent tests of popular multivitamins found that almost one-third of the products tested contained significantly more or less ingredient than claimed on the label, or were contaminated with lead.
Also, look for certain designations on the label that show the manufacturer has voluntarily subscribed to higher manufacturing practices. Several organizations offer independent verification, and if the products meet those standards for purity, quality and potency, a seal will appear on the label. For instance, U.S. Pharmacopeia has a verification mark (visit uspverified.org); Consumerlab also has its own approval process for companies that choose regular quality testing; and independent quality verification is provided by the Natural Products Association (npainfo.org) and NSF International (nsf.org).