Trouble in the dietary supplement manufacturing industry may leave consumers wondering which products are safe and which actually deliver what is listed on the "supplement facts" label. There's no way to know for sure without sending the supplements to a lab, but consumers can take some steps to minimize their risk:

Check to see if the brand has been involved in a recall or has gotten a warning letter from the U.S. Food and Drug Administration. These can be found by searching the FDA website, fda.gov. However, because many brands do not do their own manufacturing, it may be difficult to figure out which companies to check.

ConsumerLab.com, an independent group that tests dietary supplements, has a wealth of information on its website. Some information is free, but detailed results of its testing of brand-name supplements are accessible only to members. Membership is available for less than $3 a month.

Several groups certify dietary supplement firms in good manufacturing practices, including the Natural Products Association, one of the industry's largest trade groups. To find out what is involved with its certification program and which firms have met the group's criteria, which include the FDA's standards, visit the group's website at npainfo.org.

Consider the scientific evidence for taking the supplement in the first place. Are there large double-blind, placebo-controlled clinical trials showing the supplement is safe and effective? Several places to look for this kind of evidence are pubmed.gov, which lists published medical research, and cochrane.org, which offers reviews of published research.