A New Year’s resolution to take herbal supplements may seem like a good idea, but DNA tests show that many pills labeled as healing herbs are often weakened by considerable product substitution, contamination and fillers.

According to findings published in the journal BMC Medicine, Canadian researchers used a kind of genetic fingerprinting called DNA barcoding to test 44 bottles of popular supplements made by 12 companies. This same technique has also been used to uncover labeling fraud in the commercial seafood industry. The goal of the research was to protect consumers from health risks that could arise from product substitution and contamination.

Researchers found one-third of the 44 herbal supplements showed no trace of the plant advertised on the bottle. Instead, pills labeled as popular herbs were often replaced or diluted by inexpensive fillers such as wheat, rice and soybean. These activities could have harmful effects for consumers as contamination and substitution reduce the effectiveness of useful remedies and could lower consumer confidence.

With those results in mind, the Canadian researchers suggest the industry embrace DNA barcoding to authenticate herbal products and provide consumers with safe, high quality supplements.

Another finding Philadelphia researchers reported is the growing rate of liver damage linked to consuming dietary and herbal supplements. According to study, the proportion of reported cases of liver damage caused by taking these supplements has increased from 7 percent to 20 percent.

The promises of curbed hot flashes, boosted memory and enhanced immune system could be too good to be true. This New Year, resolve to be a savvy consumer before you shop for and take herbal supplements.