A new study of the workout supplement Craze shows it contains dangerous amounts of methamphetamine analog, researchers said.

The study was prompted when many failed athletic drug tests, and the users suspected it was from using Craze. Since then, suppliers such as Wal-Mart and BodyBuilding.com have suspended the sales of the product.

"In recent years banned and untested drugs have been found in hundreds of dietary supplements. We began our study of Craze after several athletes failed urine drug tests because of a new methamphetamine analog," said lead author Dr. Pieter Cohen, of Harvard Medical School, in a news release.

Study results revealed the presence of methamphetamine analog N,α- DEPEA, in three samples: one from a U.S. mainstream retailer, the second from a U.S. online retailer and the third from an online Holland retailer. The drug has not been safely tested for human consumption, according to the news release:

The team used ultra-high performance liquid chromatography to detect the presence of N,?-DEPEA. The first two samples were analyzed by NSF International, while the third was tested at the Netherland's National Institute for Public Health. The findings were independently corroborated by the Korean Forensic Service, which confirmed the presence of N,?-DEPEA in two further samples of Craze in a parallel investigation.

"We identified a potentially dangerous designer drug in three separate samples of this widely available dietary supplement," said Cohen. "The tests revealed quantities of N,?-DEPEA of over 20mg per serving, which strongly suggests that this is not an accidental contamination from the manufacturing process."

The study was published in the journal Drug Testing and Analysis.

"The phenylethylamine we identified in Craze, N,alpha-DEPEA, is not listed on the labeling and it has not been previously identified as a derivative of dendrobium orchids," said Cohen.

"If these findings are confirmed by regulatory authorities, the FDA (The U.S. Food and Drug Administration) must take action to warn consumers and to remove supplements containing N,alpha-DEPEA from sale," Cohen added. "Our fear is that the federal shutdown may delay this, resulting in potentially dangerous supplements remaining widely available."