Anyone got a hankering for some pig brains? Calf blood? Fungus from the fur of a Chinese caterpillar?

For decades, some elite athletes have pushed beyond extreme to the downright bizarre while looking for an advantage. They've ingested all sorts of animal extracts in a never-ending cat-and-mouse game with those who regulate the wild world of performance-enhancing substances.

So it's no surprise deer antlers became this year's, um, thorny issue when Sports Illustrated reported during Super Bowl week that Ravens linebacker Ray Lewis might have used deer-antler spray, which contains a growth hormone banned by the NFL. Three months later, on the eve of the PGA Tour's Players Championship, professional golfer Vijay Singh sued the Tour, claiming he suffered "public humiliation and ridicule" after admitting in the same article that he uses the spray, which was banned by the PGA Tour at the time.

Meanwhile, a spike in future use of deer-antler spray and the potential for even more controversy might have been triggered by a new and confusing stance taken by the World Anti-Doping Authority (WADA). In light of its review of the Singh case, WADA said it, "no longer considers the use of deer-antler spray to be prohibited unless a positive test results." The spray's primary performance-enhancing substance — insulin-like growth factor, or IGF-1, a precursor to producing human growth hormone (HGH) — remains on the banned list, but WADA examined deer-antler spray and decided it isn't potent enough to trigger a positive test result.

"We've already seen a spike in usage," said Rick Lentini, Ph.D, CEO of Nutronics Labs and the man credited with introducing deer-antler spray to the United States in the late 1980s. "When WADA and the PGA Tour said it was OK to use, guys ran out the next day and started buying the product."

Taking its lead from WADA, the PGA Tour removed deer-antler spray from its banned list and dropped its sanctions against Singh. IGF-1 remains banned by the PGA Tour, but can be detected only through blood testing, something the PGA Tour doesn't do.

"We ban and test for substances, not products, and IGF-1 is on our banned substance list, as it is on WADA's," NFL spokesman Greg Aiello wrote in an e-mail to the Star Tribune. "Players are advised that they take supplements at their own risk."

On Monday, it appeared the NFL and the players' association were closer to agreement on testing players for HGH. Players were informed by e-mail that they will be given blood tests for HGH when they take their training camp physicals. No discipline would result from the tests, which will be used to determine if players have higher HGH levels. The e-mails were first reported by USA Today.

The NFL players' union says it still favors blood testing but has concerns about the appeals process. Meanwhile, Major League Baseball has joined the Olympics in the use of blood testing. The NHL and NBA don't test blood, although the NBA reportedly is getting closer to doing so.

What is deer-antler velvet?

The most coveted deer- antler velvet comes from about 500 young deer that live on a farm in New Zealand. The soft coating that covers their immature antlers is harvested, freeze-dried, ground into a powder and sold in liquid spray bottles by many companies. On Nutronicslabs.com, the cost ranges from $19.99 to $189.99 per bottle (one-month supply).

"The deer aren't hurt in the process," Lentini said. "They're actually treated better than some humans."

Two squirts under the tongue three times a day is the recommended dosage. The liposome delivery system bypasses the stomach, which proponents say boosts the effectiveness of the IGF-1, a natural substance that helps build muscle, burn fat and reduce recovery time.

"The Chinese have been using deer-antler velvet for 2,000 years," Lentini said. "They didn't know all the properties in it. All they knew was it helped with a lot of ailments."

Lentini, a former semi-pro football player and bodyguard for actors such as Robert DeNiro and Kevin Costner, came across deer-antler velvet in the late 1980s. While searching for an alternative way to comfort his cousin, Michael Lentini, who was dying of Lou Gehrig's Disease, Lentini met and teamed up with Dr. Alex Duarte, a leading authority in the field.

Not everyone believes

Some of the more aggressive proponents of deer-antler spray claim the product does much more than promote muscle growth. Among other benefits, they claim it slows down the aging process, promotes a healthy prostate and increases one's libido.

Not everyone believes in the marketing pitches, however.

"I've sometimes smiled and said if a snake-oil salesman from the 1850s were to come back to life, this would be his job for the 2000s," said Dr. Larry Bowers, chief science officer for the United States Anti-Doping Agency and a former longtime professor at the University of Minnesota.

Lentini said he believes WADA's decision to remove deer-antler spray from its banned list of products proves it's natural and steroid-free. That's been up for debate since 2009, when then-Rams linebacker David Vobora failed an offseason test for the steroid methyltestosterone. He blamed it on a bottle of deer-antler spray, which tested positive for methyltestosterone, according to court documents in Vobora's lawsuit against Mitch Ross, owner of Sports With Alternatives To Steroids.

Ross said the bottle, which belonged to one of Vobora's teammates and was opened by the time Vobora used it, had been tampered with. Ross, however, didn't fight the lawsuit in court, so Vobora won by default and was awarded $5.4 million.

Lentini argues that since deer-antler spray is all-natural and steroid-free it should be embraced by athletics, particularly the NFL, since it has been known to help players recover from injuries more quickly. Former NFL fullback Heath Evans, safety Roy Williams and head coach Hue Jackson are among those on record saying the product works. The NFL has since put an end to players and coaches endorsing the product.

"The argument that it's natural, therefore it's good for you is misguided," Bowers said. "Lightning, rattlesnake venom and rat poison, strychnine, are all natural products. But I don't think I would suggest to anyone that they're good for you."

Opponents of deer-antler spray also denounce the argument that using the product is as natural as eating a steak or drinking milk, two activities that also ingest IGF-1. Opponents say the "natural" argument loses credibility with a delivery system that's contrived to bypass the stomach.

Athletes won't stop looking

This isn't the first time an animal extract has caused controversy as a performance-enhancing substance by athletes all over the world.

Pig brains reportedly have been used as amino acids to promote growth and recovery. Calf blood has been used as a growth hormone that reportedly increases an athlete's oxygen levels and stamina. And in the early 1990s, the trainer for two record-setting female Chinese distance runners attributed his athletes' success to the testosterone-boosting ingredient found in the fungus on the Chinese caterpillars they were eating in their soup.

Lentini claims "probably 40 percent" of NFL and MLB players use deer-antler spray.

"And we'd probably get 70 percent if the NFL did like the PGA Tour and said it was OK to use," Lentini said. "I'm not going to name names or throw anybody under the bus. We have to abide by HIPPAA laws. But we have doctors who work for Nutronics Labs and they talk to our clients."

Although the percentage of athletes who use deer-antler spray or HGH is unknown, no one disputes the fact that they are being used.

"I'm not naive, so I know it's out there," Vikings defensive end Jared Allen said. "I'm all for our steroid testing and [HGH testing] because I'm a guy who barely even takes protein shakes."

Like a lot of NFL players, Allen is concerned about there being a "fair and equal" process that catches cheaters but doesn't subject players to being "stuck with a needle" an inordinate number of times a year.

"Obviously, we have to get this worked out and, eventually, there's no doubt [blood testing] is going to happen," Allen said. "I would just hope that guys will take the mentality that you don't need this. You can get a lot of places in this league on hard work and effort. For me, steroids or HGH is a lazy man's way out. If you have to put that crap in your body, maybe you weren't good enough to be here in the first place."

Not every athlete believes that, which is why deer antlers have taken their place alongside the likes of pig brains, calf blood and caterpillar fungus.