Heads up, herbal supplement users: what you see may not be what you get, especially if you are buying your herbal supplements at a big-box retailer or pharmacy. A new report by the New York State attorney general's office suggests that four national retailers — GNC, Target, Walgreens, and Wal-Mart — are selling herbal supplements that do not actually contain the supplements listed on the bottle.

According to the Washington Post, the office recently completed an investigation into the sale of herbal supplements at each of the retailers and found that more often than not, the products sold did not contain any of the herbs listed on the labels. And in many cases, they contained ingredients that could be potential allergens and were not identified on the ingredient list. The attorney general has sent cease -and-desist letters to the retailers, asking them to stop selling herbal supplements. 

“Contamination, substitution and falsely labeling herbal products constitute deceptive business practices and, more importantly, present considerable health risks for consumers,” said the letters, according to the New York Times.

How did the investigators reach their conclusions? They conducted tests using a process called DNA barcoding to identify the plants contained in a particular product. The investigators tested 24 products claiming to be seven different types of herb — echinacea, garlic, gingko biloba, ginseng, saw palmetto, St. John’s wort and valerian root. Of the 24 products tested, all but five contained plants that were either unrecognizable or if they could be detected, they were not the herb listed on the product packaging. In addition, five products contained wheat or beans, two common allergens, without listing them on the product label. 

Wal-Mart was the worst offender of the bunch. Investigators tested six products from Wal-Mart and not one contained purely the herb listed on the label. Target had the best track record of the four, and that's with only one product out of six containing the ingredient listed on the bottle. 

How can products be labeled as one thing but contain another? Herbal supplements are not considered food or drugs, so they are not regulated in same ways. Federal guidelines require companies to self-regulate to make sure that their products are safe and accurately labeled, but the Food and Drug Administration has little authority to make sure that they do.

The damaging report is yet another blow to the herbal supplement industry and one that comes on the heels of the investigation that blew the lid off of "The Dr. Oz Show," finding that the good doctor's recommendations are more often wrong than right.

Bottom line: If you use herbal supplements, you should reconsider purchasing them from the four retailers listed in the investigation. And while you're at it, go ahead and double check the credibility of whichever company you choose as your source.

Related on MNN:

Big retailers accused of selling fake herbal supplements
New York Attorney General sends cease-and-desist letters to GNC, Target, Walgreens, and Wal-Mart, asking them to stop.