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Call it the burrito defense.

Shelby Houlihan recently tested positive for the anabolic steroid nandrolone, and now she faces a four-year ban from competition, ESPN reported.

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But the record holder in the 1,500 and 5,000 meters said a tainted pork burrito is the reason she’ had a positive test, not that she’s taking the medication.

On her Instagram account, Houlihan said it has “long been understood by WADA (World Anti-Doping Agency) that eating pork can lead to a false positive for nandrolone, since certain types of pigs produce it naturally in high amounts. Pig organ meat (offal) has the highest levels of nandrolone.”

The WADA sponsored a study that found that trace amounts of the steroid can be found in offal and warned that it could lead to a false positive, CNN reported.

Houlihan said she took the test on Dec. 15 and after receiving the results, she listed all of the foods that she ate before having to submit a sample.

“We concluded that the most likely explanation was a burrito purchased and consumed approximately 10 hours before that drug test from an authentic Mexican food truck that serves pig offal near my house in Beaverton, Oregon,” Houlihan said.

She added that she informed the Athletics Integrity Unit that she believes that meal was the source of the steroid.

Despite her evidence, including submitting a hair sample to toxicologists that showed no buildup of the steroid, the Court of Arbitration for Sport did not accept those findings and issued the four-year ban.

“I want to be very clear. I have never taken any performance enhancing substances. And that includes that of which I am being accused,” Houlihan said, according to ESPN.

Nandrolone is a synthetic steroid similar to testosterone and can be used to increase nitrogen retention and fat-free muscle mass, the National Institutes of Heath said, according to CNN.

The U.S. Olympic track and field trials are set to start in Eugene, Oregon on Friday. The top three athletes in each event will go to the Tokyo Games later this summer.

Houlihan is among several athletes who are banned from competing due to doping accusations and investigations, CNN reported.