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Is Nandrolone Found in Pork? All Your Shelby Houlihan Burrito Questions, Answered.

The breaking news of Shelby Houlihan's four-year ban created an outpouring of confusion. We waded through the science and research to help answer some of the top questions.

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On Monday, the track-and-field world was rocked by the news that Shelby Houlihan, American record holder in the 1500 meters and 5,000 meters, had tested positive for a banned substance called nandrolone and is now barred from competition for four years.

[You can read all the details about the announcement in our news report here.]

The resulting blizzard of news has created an outpouring of questions, many focusing on Houlihan’s claim that she ingested the substance unknowingly in a burrito purchased from a food cart near her home in Beaverton, Oregon. 

At this point, experts for the most part, are reluctant to weigh in. But there is a plethora of scientific literature on the subject (much dating all the way back to the 1970s), and a few experts who were willing to talk off the record. Based on that, here are some of the more pressing answers.

What is nandrolone, and why should I care about it?

Nandrolone is an anabolic steroid, meaning it is a compound somewhat like testosterone, a hormone that can boost strength by helping muscles bulk up. At low levels, it’s natural in males and to a lesser degree in females, and is part of a family of compounds involved in the synthesis of testosterone, which occurs in the testes of men and in the ovaries of women.

Nandrolone and related compounds are actually detected by measuring yet another compound, 19-norandsterone, in urine samples, which is normally present at up to .5 parts per billion (ppb) in both women and men, especially after a hard workout. A positive test is considered 2 ppb or above, for both women and men.

However, higher levels of 19-norandsterone can also be present in urine samples of pregnant women, so according to the recommendations of the International Olympic Committee (IOC), doping control urine samples from pregnant women containing more than 5 ppb have to be reported negative. (Houlihan was not pregnant at the time of the test, as confirmed by her team during the press conference.)

Technically speaking, Houlihan’s drug test was positive for 19-noradrosterone (at 5 ppb), not for nandrolone, but even the Court of Arbitration for Sport in its press release refers to the test as positive for nandrolone, a simplification we will also use for the rest of this article.

Steroids have their usesnandrolone is sometimes used, for example, in the treatment of anemia, osteoporosis, chronic kidney disease, and breast cancer. But its ability to mimic testosterone and increase strength and ease of recovery after a workout are what make it a performance-enhancing drug, or PED. (For decades, it has been one of the dopers’ steroids of choice. It was the steroid for which Marion Jones’s then-husband, shot putter C.J. Hunter, tested positive in 2000.) It’s banned not because it works, necessarily, but because using it carries the risk of dangerous side effects, which for women include infertility, and possible increased risk of heart disease and stroke.

Is nandrolone found in pork? And could Houlihan really have gotten it from a burrito?

Yes, it is possible. Nandrolone and related compounds do occur naturally in meat, especially that of male animals, particularly uncastrated hogs (boars). And while boar meat is a small fraction of the overall pork supply (about 2 percent, according to Houlihan’s attorney, Paul Greene) “small” isn’t the same as “none.” Furthermore, nandrolone is concentrated in boar offal (organ meat), which is what Houlihan says was used by the food cart she visited. 

What is offal, and why would she eat it?

Offal is the entrails or internal organs of an animal used as meat. If you’ve ever eaten liver, you’ve eaten offal. Houlihan claims that she ordered a carne asada burrito (which should have been beef) but got something unusually greasy and not like normal carne asada. She and Greene believe she was accidentally served a pork burrito made from pork stomach meat.

“We have the receipt and the iPhone tracking [data],” Greene’s associate, Matthew Kaiser, told Women’s Running in a phone call on Wednesday. “We talked to the proprietor of the food truck and they use pig stomach in two of their burritos, which increases the odds that she was handed the wrong one.”’

The name of the food truck has not been publicly released, nor has any information regarding where the food truck sourced its meat in December 2020.

Are analytical tests really sensitive enough to detect the result of eating a single contaminated burrito?

Yes. Two decades ago at a meeting of the American Association for the Advancement of Science, Ronald Hites, a professor of analytical chemistry at Indiana University, flashed a slide on the screen titled “Prefixes of Increasing Nothingness.”

When he was young, Hites (now 79) said, “milli-” (as in milligrams) was considered an extremely sensitive test within the field of analytical chemistry. Then it became micrograms. Then nanograms. Then picograms. Each prefix (milli-, micro-, nano-) represented a 1,000-fold improvement in analytical technology, with a new prefix becoming the norm each decade. 

By the mid-1990s, researchers at Iowa State University had demonstrated that it was possible to detect—and count—single molecules at the “atto-” level, or one billion times below the nano- level. 

Not that this is what was done with Houlihan’s urine sample—that was measured at the parts per billion level—but the science is clear: If you are looking hard enough, you can detect tiny enough amounts of pretty much anything, anywhere.

Furthermore, research has found that a single serving of meat from a boar—especially offal—is high enough in nandrolone to trigger a positive result in a drug test, especially within the next few hours. Urine levels of this compound can easily reach 50 percent higher than those found in Houlihan’s testing sample, a team led by Canadian anti-doping specialist Christiane Ayotte reported in 2006 in the British Journal of Sports Medicine, “with levels even reaching 160 ng/ml (160 ppb) in one case.”

Ayotte was unavailable for comment, but noted in her 2006 article, “athletes should prudently avoid meals composed of pig offal in the hours preceding [a] test.”

This, of course, means that athletes both know they are eating pig offal and know a test is looming. Which brings our next question.

Are these tests really random? How frequently do they occur and what’s the protocol?

The answer depends on how high up you are in the athletic food chain, but for an Olympic medal hopeful like Houlihan, the answers are “yes” and “often.”

Athletes enter the drug-testing pool based off their rankings and performances. They can be tested by the U.S. Anti-Doping Agency (USADA) or the Athletics Integrity Unit (AIU), an independent body created by World Athletics (the international governing body of track and field). In Houlihan’s case, she was tested by the AIU. 

The out-of-competition protocol is simple. Athletes have to provide drug-testing authorities with a calendar of where they will be every day, along with one-hour time slots when they will be available for testing. (This can be changed as needed, by updating their calendars.) “Athletes, who are asked to provide a urine or blood sample (or both), are subject to testing 365 days a year and do not have ‘off-seasons’ or cutoff periods in which testing does not occur,” the U.S. Anti-Doping Agency (USADA) writes on its website. Missing a test is a “whereabouts failure,” which, if repeated, can lead to a ban—not for doping, but for dodging the testers.

An athlete who is frequently tested isn’t automatically suspected of doping and many athletes welcome unannounced testing because it discourages cheating. In 2020, Houlihan was tested 16 times by USADA (AIU does not publish a database with the same information), but she wasn’t the most-tested U.S. pro runner last year—that was Aliphine Tuliamuk, who was tested 20 times by USADA. Houlihan had never tested positive for a performance-enhancing drug prior to December 2020. She’s been tested nine times by USADA in 2021.

It’s not a new process. Nearly two decades ago, at a symposium on doping in Portland, Oregon, one of the first things Olympic silver medal cyclist Mari Holden said she did after accepting the speaking engagement was to inform the doping authorities of her agenda, in case they chose to test her while she was on the road.

This is a theme you’ll hear commonly repeated among top runners today: Any move they make, they let the drug testers know about it, so as not to ever miss a test. Annoying? Maybe. But a bit of annoyance is sometimes a small price to pay for the chance to pursue your dreams.

So how do we know it came from pork and not a pill?

The answer to this gets complex fast, and is easily muddled. “People want to simplify everything [but] it’s science. It’s not simple,” Greene told Women’s Running in a phone call on Wednesday.

So, let’s bear with him, even though it’s going to dive us into isotope ratios, photosynthesis, and things way beyond one’s normal range of knowledge.

The scientific issue comes down to something called δ13C ratios (pronounced delta C-thirteen). “C” is carbon, which generally is composed of 6 protons and 6 neutrons, totaling an atomic mass of 12—what physicists and chemists call 12C. But that’s not the only form of carbon. There is also 14C, which is radioactive and used for carbon dating (not relevant here) and 13C which has 6 protons and 7 neutrons, is stable and comprises a little more than one percent of the world’s total carbon.

On first blush, 12C, and 13C are chemically identical. They form the same compounds, and react similarly with other compounds. But 13C is 8 percent heavier, and that changes how it interacts in chemical processes, with some processes favoring the lighter isotope, and some treating them more equally. From this, scientists can determine, among other things, if the source of a chemical is a biological process or a laboratory process. 

But it gets more complex than that, because different types of biological processes favor 12C differently than others.

Which brings us back to Houlihan and her burrito. 

Only Houlihan knows what she ate that night. But nandrolone from pork and nandrolone from her own body are distinguishable by their δ13C ratios not only from synthetic nandrolone, but from each other. That’s because different types of plants use different types of photosynthetic processes (known to biologists as C3 and C4 processes), which produce different δ13C ratios. Americans eat diets based on plants like corn, which, Houlihan’s team argues, slant toward C4. Hogs are fed soybeans, which slant more toward C3. 

It’s a method that’s been long used by anthropologists to trace the evolution of the human diet, but what it means for corn-fed Americans, Greene says, is the δ13C ratios in their own bodies are typically in the -18% to -20% range. For soy-fed hogs, he says, it can be larger (-21% to -25%), but not as large as for synthetic nandrolone, which, he says, runs at -27% to -30%. Houlihan’s, he says, was -23%, consistent with her story. 

That said, a three-judge panel from the Court of Arbitration for Sport ruled against her. Why they ruled against her isn’t clear at this time. 

All they said, in a brief May 15 press release was, “[T]he CAS Panel unanimously determined that Shelby Houlihan had failed, on the balance of probability, to establish the source of the prohibited substance.” Period, end of sentence. 

It’s possible that the judges were relying on a 2018 paper in the journal Drug Testing and Analysis in which a team of British researchers led by Alan Brailsford of King’s College London measured the δ13C values of 14 different preparations of nandrolone and testosterone. Ten of them, they reported, came back in the range normally expected for synthetic steroids (-27% or or larger). But four of them, all nandrolone, came up with values that overlapped those consistent with endogenous nandrolone. If these formulations were to be used by dopers, the researchers concluded, that could be a problem in determining the source of nandrolone in anti-doping cases. 

Whether this played a role in the decision, however, won’t be clear until the judges issue a more detailed explanation of their ruling. (More on that later.)

What’s all this stuff about hair sampling?

When Houlihan first learned of the laboratory finding that tripped her positive test, she sent a 20-centimeter (8-inch) sample of her hair to a lab in France to test for nandrolone residues. That’s important because hair, which grows at the rate of about a centimeter a month, contains residues of chemicals to which you might have been exposed during that time. Analyzing these is, to forensic scientists, akin to an archaeologist digging through ancient layers of the past.

It’s not a perfect record, and not usable to convict a person of a doping violation, forensic toxicologist Pascal Kintz of X-Pertise Consulting and the Institut de Médecine Légale, Strasbourg, France, wrote in a 2020 paper in the Journal of Analytical Toxicology. But, he says, it is widely applied for many other legal purposes. “It’s use…is accepted in most courts of justice in the world,” he wrote.

One downside, he wrote, is that it can’t detect a single exposure to some drugs, including anabolic steroids (presumably including nandrolone). And, he added, it might also miss repeated, low oral doses of steroids—e.g., microdosing. But it would detect more severe doping in the form of injections. Based on this, Kaiser says, “the conclusion [from Houlihan’s hair sample] was that there was no repetitive exposure to nandrolone within the past six months.” 

(Women’s Running contacted the likely testing facility and received no official comment.)

Has this ever happened to anyone else?

Yes. The most famous case might be U.S. long jumper Jarrison Lawson, who was banned when a urine test revealed the steroid trenbolone in his urine. Lawson sat out 19 months of a four-year ban before the highest tribunal of the Court of Arbitration for Sport ruled that the steroid had come from a beef bowl he’d eaten in a Japanese restaurant in Arkansas the day before the test. (Trenbolone is often used as a growth enhancer in U.S. beef cattle.)

In Lawson’s case, it helped that the restaurant was able to refer authorities to its beef supplier, who admitted it used trenbolone. Houlihan’s burrito is long gone, and there’s no way now to prove it came from an uncastrated boar, rather than a more ordinary hog. But Lawson’s case is still a precedent.

Another is the case of Chinese hammer thrower Wenxiu Zhang, who was banned for the presence of zeranol in her urine. In her case, Kintz wrote, hair testing helped reveal that the substance came from moldy food.

And, 800-meter American record-holder Ajee’ Wilson avoided a ban in 2017 when she tested positive for zeranol, yet another anabolic steroid used as a growth promoter in U.S. beef.

RELATED: How Olympian Ajee’ Wilson Keeps Her Cool

What’s next?

That’s the million-dollar question. The complete “reasoned decision” is expected from the panel…sometime. “In due course” is what was initially said, but it’s since been expedited to “in short order.” Best guess, weeks, maybe a couple months.

Meanwhile Houlihan’s attorneys haven’t given up on getting her into the Olympics. Greene says he’s already filed for an injunction from the CAS’s highest court in Lausanne, Switzerland, to put this week’s ruling on hold pending an appeal. “There is an expedited process,” he says.

U.S.A. Track & Field issued a statement on Thursday saying that Houlihan is allowed to compete at the Olympic Trials. She currently appears on the entry lists and heat sheets for the first rounds of the 1500 meters and the 5,000 meters, both scheduled for Friday.

As of Thursday, Houlihan’s agent would not comment on whether Houlihan will compete or not.

RELATED: You Don’t Know Shelby Houlihan