(CNN) Bruce Lee was training a friend one day when he did something unexpected.

The star of the classic film, "Enter the Dragon," was already known for his fanatical fitness regimen. He didn't smoke or drink; he gobbled vitamin supplements and drank raw blended hamburger meat. He'd transformed himself into a lithe fighter who could do two-finger push-ups and send burly men flying with his famed one-inch punch.

But Lee ended the training session at his home on this particular day with a different type of flourish. He lit a joint and started puffing away. It came from a box of marijuana cigarettes he kept in his garage. Lee would later move on to hashish, carrying it around in little bags and nibbling on it like edibles.

"It raises the consciousness level," Lee explained when another martial artist asked him why he got high.

That's not the type of story one typically hears about Lee. Since he died at age 32, his legend has grown to such mythological levels that one martial artist calls him "kung fu Jesus." A new biography, though, debunks some of the most popular myths about the man.

Bruce Lee's role as "Kato" in the TV series, "The Green Hornet," made him a star in Hong Kong.

"Bruce Lee: A Life" by Matthew Polly is the first in-depth account of Lee's journey from a street-brawling teenager to a global icon. The book, which comes on the 45th anniversary of Lee's death, features interviews from everyone from his childhood classmates to friends who saw him smoke up to the woman who last saw him alive. Lee's charisma, ambition and relentless appetite for combat leap off the pages. You can practically hear his catlike shrieks in some of the most vivid sections.

If you think you know Lee, this book may shock you.

Among its surprises:

- Lee was a "kinetic genius" who could quickly master any martial arts fighting style. But he never learned to ride a bike and was declared medically unfit for the draft after failing his physical.

- He has been portrayed as an impoverished immigrant who came to America to make it big, but he actually grew up in an affluent Hong Kong family with its own chauffer and two live-in maids.

- He is seen as a Chinese superhero with a statue in Hong Kong, but he was also part Jewish.

Polly, who interviewed at least 100 of Lee's friends and family members, says people often forget that Lee was virtually unknown in the United States when he died. His breakthrough movie, "Enter the Dragon," was released less than a month after his mysterious death in Hong Kong in July 1973.

Nobody watched a Steve McQueen movie and took up something. People study martial arts because of Lee, and it changed their lives for the better. Bruce Lee has a place in a lot of fans' hearts as a demigod, or what I call a patron saint of kung fu. He had a missionary effect. Matthew Polly, author of "Bruce Lee: A Life"

Lee is the only major Western icon whose fame is entirely posthumous, says Polly, who, as a skinny, bullied kid, was inspired by Lee's films to later move to China and study kung fu at a Shaolin temple.

Lee wasn't just an entertainer; he was an evangelist. Millions took up martial arts because of him, Polly says.

"No other celebrity changed people's lives in that way," Polly says. "Nobody watched a Steve McQueen movie and took up something. People study martial arts because of Lee, and it changed their lives for the better. Bruce Lee has a place in a lot of fans' hearts as a demigod, or what I call a patron saint of kung fu. He had a missionary effect. "

He never apologized for being Asian

He also changed the way many Westerners regarded Asians, Polly's book shows.

Lee was the "the first Asian American actor to embody the classic Hollywood definition of a star," Polly wrote. "Men wanted to be him and women wanted to be with him."

Lee's pride in his heritage was contagious.

"More than anything else, what I liked most about Bruce was that he never apologized for being Oriental," says one of Lee's college girlfriends, a Japanese-American, in the book. "In a time when so many Asians were trying to convince themselves they were white, Bruce was so proud to be Chinese he was busting with it."

Asian men were not traditionally depicted as sexual beings in Western films. Even Lee had only one brief love scene in the three movies he made. Away from the screen, though, Lee was a ladies' man.

Lee was married with two kids but was caught up in the "Swinging Sixties free love ethos" and had extramarital affairs, Polly writes. There's one passage in the book where a former mistress of Lee's raves about how "knowledgeable" he was about a woman's body.

The book also offers a peek into the Hollywood culture of the late 1960s and early '70s, with intimate accounts of Lee's friendships with stars like McQueen and James Coburn and the writer Stirling Silliphant. There's a wonderful scene where Lee uses a martial arts lesson with Silliphant to unlock the writer's repressed feelings about his father.

It turns out Lee was a bit of a hippie, too. At one time, he wore his hair long, sported love beads and donned dashikis. And he got high, which surprised some of the martial artists who trained with him. One judo expert quoted in the book stopped training with Lee at his home because he was sick of all the pot smoke swirling around.

Lee, with his wife, Linda, was a racial pioneer in many ways. His interracial marriage was rare at the time, and he broke martial arts tradition by teaching students of all races.

Polly says he wasn't trying to be salacious. He wanted to show another side of Lee beyond the "patron saint of kung fu" image. He interviewed Lee's widow and daughter for the book but hasn't heard from them since it published last month. Neither responded to CNN's request for comment.

"I hope one day that they will see it as it is," Polly says. "It was written from a place of love."

Davis Miller, author of "The Tao of Bruce Lee," says "fan-boys" won't love Polly's book.

"Those guys need to believe in kung fu Jesus," says Miller, whom Polly consulted for his bio. "And they're not getting that. They're getting a guy who is human."

Taking out Sammy Davis Jr.'s bodyguard

Lee, indeed, seemed superhuman in his film's fight scenes. But how good was he when the cameras weren't rolling? People still debate that question.

I don't think the guy was ever tested. Bruce Lee didn't have the real-world experience that boxers had. Davis Miller, author of "The Tao of Bruce Lee"

Miller says Lee was probably the "best martial artist at the time of his death" but wasn't unbeatable. Though Lee trained with and taught martial arts champions like Chuck Norris and Joe Lewis, Miller says he's not sure how Lee would have fared in a fight against a top-flight boxer.

"I don't think the guy was ever tested," Miller says. "Bruce Lee didn't have the real-world experience that boxers had."

One man who saw Lee fight has no doubt about what he could do.

Doug Palmer was one of Lee's first students in America. He is one of a small group who trained with and learned directly from Lee. Palmer, who appears in Polly's book, met Lee when the martial artist was 20 and knew him until his untimely death. At one point, Lee even moved in with Palmer's family.

"He had no compunction, no hesitation about testing himself against the biggest, the fastest, and the best in whatever he came across," Palmer, now an attorney in Seattle, told CNN.

Bruce Lee, seen here in his 1971 film, "Fists of Fury," knew before his untimely death that he would be a big star in America, the author of his new bio says.

Lee didn't have many street fights as an adult because he quickly showed would-be aggressors they didn't stand a chance, says Palmer who is writing a memoir entitled, "Bruce Lee: Sifu, Friend and Big Brother."

"Most challenges he could handle without a fight," Palmer says. "The way that he could tie somebody up or hit them at will or deflect their punches at will -- it was very clear. Very few people would push that."

Polly says everybody he talked to who saw Lee spar or fight rendered the same verdict: He was "very, very, very good.''

Polly listed the reasons why: Lee was a "genius at body movement" who could master any martial arts style. He could read his opponents and know when and how they were going to attack, seemingly before they even moved. And he had otherworldly quickness; Polly says Lee's body was like "one giant fast-twitch muscle."

"He fought a lot. He liked to fight. It made him happy," Polly says.

Lee would often greet other martial artists and street brawlers with the same invitation: "Hit me as hard as you can with either hand whenever you are ready," Polly writes. He would then brush away their punches "as easily as you would a baby" and counter with strikes that would stop inches away from their target.

He had no compunction, no hesitation about testing himself against the biggest, the fastest, and the best in whatever he came across. Doug Palmer, one of Bruce Lee's first students in America

Sometimes Lee didn't hold back. When a Japanese karate expert challenged him, Lee knocked the man out in 11 seconds. But Lee didn't always dominate. Polly tells a charming story of Lee lightly sparring with his first master, the legendary Ip Man, who by that time was elderly but could more than hold his own.

Polly tells another story about Lee taking out a "humongous" bodyguard of Sammy Davis Jr. Lee was accompanying two friends during his days as a struggling actor when the trio ran into the bodyguard near a Las Vegas casino. The man suddenly raised his hand to wave at someone behind Lee, but Lee thought the bodyguard was about to attack him.

Quicker than a blink, Lee kicked out one of the bodyguard's legs, locked up his arms, bent him backwards until he was helpless, "and went right at his throat with the points of his fingers," Polly writes. The story ended with Lee's apology and the bodyguard asking, "What the hell did you do to me?"

How Lee really died

One of the most intriguing sections of Polly's book deals with Lee's death.

The conventional explanation is that Lee died from a cerebral edema, or swelling of the brain, caused by a reaction to a painkiller he had taken for a headache. But all sorts of conspiracy theories about his death abound, among them: Lee was felled by a family curse or taken out by the Chinese mafia.

Brandon Lee, like his father, died young and on the cusp of movie stardom.

Polly offers a more prosaic explanation: heatstroke.

He says it's common for heatstroke victims to suffer from swelling of the brain. Lee had several risk factors for heatstroke: He had collapsed three months earlier after isolating himself in a hot editing room without air conditioning; he'd had his armpit sweat glands removed because he disliked sweat stains on his clothes; and the impending release of "Enter the Dragon" kept him from sleeping and eating.

Even supremely conditioned young athletes die of heatstroke, Polly points out. He cites Korey Stringer, a Minnesota Vikings NFL player who died of heatstroke at a training camp in 2001. Lee died on one of the hottest days in Hong Kong, Polly notes.

"He's in perfect shape. All he does is work out," Polly says. "But if you haven't been sleeping, if you've lost a bunch of weight, if you remove the sweat glands under the armpits, then you're less likely to deal with heat than you would have beforehand. Even a healthy man can die in those conditions."

Lee was on the cusp of international fame when he died. He was negotiating the creation of an animated series and a clothing line, and movie studio offers were tumbling in because of buzz over "Enter the Dragon." He had even been booked to appear on "The Tonight Show" with Johnny Carson.

"He knew he was going to be a superstar, and he was getting ready for it," Polly says.

Bruce Lee, hailed as a hero by many in China, is honored with a statue in Hong Kong. Some Chinese discriminated against him because of his Eurasian heritage.

Today, he's become something else -- a global icon who is arguably one of the most recognizable men on the planet. There probably isn't any country in the world where some young man or woman doesn't have a poster of Bruce Lee on a bedroom wall.

Who could have predicted Lee's posthumous fame? Long before he found Hollywood, only Lee seemed to sense what might be in store. When he was 21 -- and fighting loneliness and racism after coming to America -- Lee wrote a letter to his former high school sweetheart.

"I feel I have this great creative and spiritual force within me that is greater than faith, greater than ambition, greater than confidence, greater than determination, greater than vision," he wrote. "It is all of these combined."

Lee doesn't come off as perfect in Polly's book; he's no kung fu Jesus who never lost a fight. But after 45 years of steadily turning him into a superhuman figure, perhaps people are ready for Lee to become something else:

An extraordinary young man who still inspires millions despite his share of human weakness.