Evidence of a natural origin for banned drug that plumps up livestock

Julie Vanden Bussche and colleagues explain that thiouracil is a drug that increases the weight of livestock by making them retain water. Some regulatory agencies have banned its use because the extra weight cheats consumers, who buy water for the price of meat, and because of potential adverse health effects. To keep an eye on compliance, government agencies test animals for thiouracil. For example, both the U.S. Department of Agriculture and the European Union Reference Laboratories developed sensitive tests to detect thiouracil. Perhaps because these tests are so sensitive, the drug is now showing up often but at low levels -- levels that are lower than expected if the animals were purposely doped. Hence, some scientists speculated that thiouracil may also have a natural origin. To settle the controversy, the researchers analyzed livestock feed and other food for the presence of thiouracil.

They found that plants in the family called Brassicaceae -- which includes cruciferous vegetables, such as broccoli and cauliflower, and other plants, such as rapeseed and feeding cabbage, that are used as animal feed -- had small amounts of thiouracil in them naturally. "To the best of our knowledge this study is the first to report the presence of naturally occurring thiouracil in feed and food samples, hereby elucidating and acknowledging a natural origin for the low-level residues detected in urine of various species," say the researchers.

The authors acknowledge funding from the Research Foundation-Flanders.