Canelo Alvarez
Boxer Canelo Alvarez poses during a news conference at Microsoft Theater at L.A. Live to announce the upcoming rematch against Gennady Golovkin on Feb. 27, 2018, in Los Angeles, California. Kevork Djansezian/Getty Images

Former heavyweight champion Evander Holyfield believes any boxer that intentionally takes banned substances that are performance enhancers should be given jail time.

The topic comes in the midst of Canelo Alvarez's current investigation after he recently tested positive for clenbuterol, a banned substance commonly used by athletes as a fat-burner to help them cut weight.

Traces of the substance found in the Mexican's samples from February threatened to scupper his highly-anticipated rematch against Gennady Golovkin set to take place in Las Vegas on May 5.

However, his camp are adamant the traces are likely to have come from a case of contaminated meat Canelo consumed in Mexico, where the substance is commonly used in the meat trade, with the 27-year-old later offering to submit any additional tests to prove his innocence.

"I am an athlete who respects the sport and this surprises me and bothers me because it had never happened to me," Alvarez said in a statement. "I will submit to all the tests that require me to clarify this embarrassing situation and I trust that at the end the truth will prevail."

The Nevada Athletic Commission (NAC) are now investigating Canelo on whether his consumption of the substance was intentional, before making a decision on whether the middleweight title clash will proceed, though it is expected to resume as normal.

While Canelo is likely to be innocent, there have been many cases of boxers testing positive for performance enhancing drugs with intentional use and Holyfield offered a solution to stop it from happening again.

“Put people in jail for 30 days. Stop it then," Holyfield told SiriusXM Boxing, as per "You’re touching drugs — they suspend you and it costs you money. They talk about 'get over it' [but] that don’t really work because somebody, one of the fighters trains real hard their whole life."

"People don’t know how bad it hurts people when they get robbed. That’s what boxing is. Some people don’t have a lot of people following them but that doesn’t mean they’re not a great fighter."

Canelo is not the first boxer to have tested positive for clenbuterol. The likes of Erik Morales in 2012 and Francisco Vargas in 2016 also tested positive for the substance but were allowed to fight after they blamed the tests on contaminated meat.

Canelo and Golovkin fought a controversial split-decision draw in their first meeting back in September last year, with many in the boxing world giving the latter the edge on the scorecards.

The former started the fight and ended the fight strongly but it was "GGG" who dominated a majority of the rounds in between. Judge Adelaide Byrd in particular, was highly scrutinized after she gave Canelo a 118-110 scorecard, essentially perceiving him to have won 10 rounds during the 12-round classic.

Despite the judge's controversial scorecards, the rematch will once again take place in Sin City with Golovkin putting his World Boxing Association (WBA), World Boxing Council (WBC), International Boxing Federation (IBF), and International Boxing Organization (IBO) middleweight titles on the line.