A US Olympic medal contender blamed a pork burrito after receiving a doping ban that will see her miss the Tokyo Games

• American Olympian Shelby Houlihan blamed a burrito for landing her a four-year ban from athletics.
• The 28-year-old tested positive for the banned substance nandrolone back in January.
• Houlihan says that she ate pork offal, which studies say can contain nandrolone, before the test.

The American Olympian Shelby Houlihan has blamed a burrito for landing her a four-year ban from athletics after she tested positive for a banned substance.

The Athletics Integrity Unit announced on Friday that the 28-year-old had been handed the ban by the Court of Arbitration for Sport after the anabolic steroid nandrolone was found in a doping sample in January.

Houlihan is the US record holder in both the 1500 meter and 5000 meter and competed at the Rio Olympics in 2016. She was expected to be a medal contender at the Tokyo Games this summer.

Houlihan denied ever doping, saying she had never heard of nandrolone until she saw her positive test result. She said the steroid might have gotten into her system by way of a pork burrito.

"I want to be very clear. I have never taken any performance enhancing substances. And that includes that of which I am being accused," she said in a statement on Instagram on Monday night.

"I believe in the sport and pushing your body to the limit just to see where the limit is."

Houlihan said that after she was initially notified of her positive test, she put together a food log of everything she had eaten over the past week in order to help trace the source of any possible positive test.

She said she believes that eating a pork burrito from a food truck likely caused the positive test.

She went on to say that eating pork can cause high levels of nandrolone, and lead to false positive doping tests, something she said the World Anti-Doping Agency has long been aware of.

"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," she said, saying that offal - or internal organs - has the highest level of nandrolone of any part of the pig.

In 2020, a study published by researchers at the German Sport University Cologne and the University of Munich, showed that eating the "offal of noncastrated pigs" can cause nandrolone to appear in human urine samples. A 2000 study from France's Ecole Nationale Vétérinaire showed similar results.

Houlihan continued: "Although my levels were consistent with those of subjects in studies who were tested 10 hours after eating this source and WADA technical guidelines require the lab to consider it when analyzing nandrolone, the lab never accounted for this possibility."

Houlihan will miss the Tokyo and Paris Olympics

She went on to say that she "did everything" she could to prove her innocence, including passing a polygraph test and having her hair analyzed by a toxicologist but that ultimately her arguments were dismissed.

"I feel completely devastated, lost, broken, angry, confused and betrayed by the very sport that I've loved and poured myself into just to see how good I was," she said.

Houlihan's ban, which has been backdated to January, means she will miss two Olympic Games.

As Tokyo 2020 is being held a year late thanks to the coronavirus pandemic, the next summer Olympics, in Paris in 2024, is just three years away.

Houlihan's coach, Jerry Schumacher, also criticized the ban, calling it a "great tragedy in the history of American distance running," according to The Guardian.

Houlihan's ban is the second time in less than six months that an elite athlete has cited the ingestion of pork as a reason for failing a drug test.

In February, the Kenyan distance runner James Kibet was handed a four-year ban after testing positive for nandrolone. He also argued that the test was caused by consuming pork.

Kibet said that he had ingested a pork-fat syrup up to three times a day while in Italy for a race in 2019, according to the Sports Integrity Initiative.

The Athletics Integrity Unit rejected Kibet's argument, saying that it was his own responsibility to "ensure no prohibited substance" entered his body. His ban was backdated to 2019.