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Image 2 of 48 Singer/songwriter Carrie Underwood became a vegan after years of vegetarianism. Singer/songwriter Carrie Underwood became a vegan after years of vegetarianism. Photo: Rick Diamond / Getty Images

Image 3 of 48 Actress Tia Mowry went vegan and she says she feels better and has more energy. Actress Tia Mowry went vegan and she says she feels better and has more energy. Photo: Jason LaVeris / FilmMagic

Image 4 of 48 Designer/actor/singer Andre Benjamin, also known as Outkast's Andre 3000, was voted as one of PETA's sexiest vegetarian celebrities in 2004. Designer/actor/singer Andre Benjamin, also known as Outkast's Andre 3000, was voted as one of PETA's sexiest vegetarian celebrities in 2004. Photo: Stephen Lovekin / Getty Images

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Image 6 of 48 Actor Alec Baldwin recently stopped eating meat, as well as narrated a PETA video, "Meet Your Meat." Actor Alec Baldwin recently stopped eating meat, as well as narrated a PETA video, "Meet Your Meat." Photo: Stephen Lovekin / Getty Images

Image 7 of 48 Mike Tyson credits veganism with improving his life after years of drug use. (Photo by Gabriel Olsen/FilmMagic) Mike Tyson credits veganism with improving his life after years of drug use. (Photo by Gabriel Olsen/FilmMagic) Photo: FilmMagic

Image 8 of 48 Former U.S. President Bill Clinton began a vegan diet after his heart surgeries, and he wanted to shape up and lose weight before daughter Chelsea's 2010 wedding. Former U.S. President Bill Clinton began a vegan diet after his heart surgeries, and he wanted to shape up and lose weight before daughter Chelsea's 2010 wedding. Photo: Slaven Vlasic / Getty Images

Image 9 of 48 Biz Stone, co-founder of Twitter, became a vegan after a visit to Farm Sanctuary, which houses animals rescued from factory farms. Biz Stone, co-founder of Twitter, became a vegan after a visit to Farm Sanctuary, which houses animals rescued from factory farms. Photo: KIMIHIRO HOSHINO / AFP/Getty Images

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Image 11 of 48 Actor/comedian Russell Brand has been a vegetarian since he was 14 and became a vegan in 2011 after watching the documentary "Forks Over Knives." Actor/comedian Russell Brand has been a vegetarian since he was 14 and became a vegan in 2011 after watching the documentary "Forks Over Knives."

Image 12 of 48 Chelsea Clinton is a vegan. She reportedly served vegan dishes and a vegan and gluten-free cake at her wedding. Chelsea Clinton is a vegan. She reportedly served vegan dishes and a vegan and gluten-free cake at her wedding. Photo: Neilson Barnard / Getty Images

Image 13 of 48 Actor/rapper Common was a vegan, but he now eats dairy and fish. Actor/rapper Common was a vegan, but he now eats dairy and fish. Photo: Frazer Harrison / 2012 Getty Images

Image 14 of 48 Actress Daryl Hannah is a longtime environmental activist and vegan. Actress Daryl Hannah is a longtime environmental activist and vegan. Photo: Frederick M. Brown / Getty Images

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Image 16 of 48 Actress Portia de Rossi and comedian/talk show host Ellen DeGeneres. The couple are both vegans. Oh, and Ellen has a blog: http://vegan.ellen.warnerbros.com. Actress Portia de Rossi and comedian/talk show host Ellen DeGeneres. The couple are both vegans. Oh, and Ellen has a blog: http://vegan.ellen.warnerbros.com. Photo: Christopher Polk / Getty Images for PCA

Image 17 of 48 "Extremely Loud and Incredibly Close" author Jonathan Safran Foer is a vegetarian. He also wrote the 2009 book "Eating Animals," which Natalie Portman cites as turning her vegan (until her pregnancy). less "Extremely Loud and Incredibly Close" author Jonathan Safran Foer is a vegetarian. He also wrote the 2009 book "Eating Animals," which Natalie Portman cites as turning her vegan (until her ... more Photo: Fernando Leon / Getty Images

Image 18 of 48 "Glee" actress Jane Lynch is vegan. "Glee" actress Jane Lynch is vegan. Photo: Kevin Winter / Getty Images

Image 19 of 48 Former "My So-Called Life" actor and 30 Seconds to Mars musician Jared Leto says he's a strict vegan. Former "My So-Called Life" actor and 30 Seconds to Mars musician Jared Leto says he's a strict vegan. Photo: Theo Wargo / Getty Images for Samsung

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Image 21 of 48 Actress Jessica Chastain, who recently starred in "The Help" and "Tree of Life," is a vegan. Actress Jessica Chastain, who recently starred in "The Help" and "Tree of Life," is a vegan. Photo: Frazer Harrison / Getty Images

Image 22 of 48 Heather Mills, ex-wife of Sir Paul McCartney, is a vegetarian and animal-rights advocate. She recently opened the V Bites Vegan Restaurant in Brighton, England. Heather Mills, ex-wife of Sir Paul McCartney, is a vegetarian and animal-rights advocate. She recently opened the V Bites Vegan Restaurant in Brighton, England. Photo: Tim Whitby / Getty Images

Image 23 of 48 Musician Moby has been a vegan for over 20 years. Musician Moby has been a vegan for over 20 years. Photo: Ethan Miller / Getty Images

Image 24 of 48 Former Smiths frontman and singer Morrissey has been a vegetarian since he was "11 or 12 years old." Former Smiths frontman and singer Morrissey has been a vegetarian since he was "11 or 12 years old." Photo: MARTIN BERNETTI / AFP/Getty Images

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Image 26 of 48 Actress Natalie Portman has been a vegetarian since she was 8, and was vegan until she was pregnant and started craving eggs and dairy. She also has a line of vegan shoes. Actress Natalie Portman has been a vegetarian since she was 8, and was vegan until she was pregnant and started craving eggs and dairy. She also has a line of vegan shoes. Photo: Michael Buckner / Getty Images

Image 27 of 48 Actress Olivia Wilde was a vegan, but reportedly sought comfort in cheese after her divorce in 2011. She now sticks to a vegetarian diet. Actress Olivia Wilde was a vegan, but reportedly sought comfort in cheese after her divorce in 2011. She now sticks to a vegetarian diet. Photo: Alberto E. Rodriguez / Getty Images

Image 28 of 48 Ozzy Osbourne cut out meat and dairy from his diet in late 2011 in a bid to get healthier. Ozzy Osbourne cut out meat and dairy from his diet in late 2011 in a bid to get healthier. Photo: Larry Busacca / 2011 Getty Images

Image 29 of 48 Actress Pamela Anderson has been a vegetarian for years, and is an outspoken animal rights activist and PETA spokesperson. Actress Pamela Anderson has been a vegetarian for years, and is an outspoken animal rights activist and PETA spokesperson. Photo: Michael Buckner / Getty Images

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Image 31 of 48 Former Beatle Sir Paul McCartney has been a vegetarian for over 25 years. He co-authored "The Meat Free Monday Cookbook," with his daughters Mary and Stella. Former Beatle Sir Paul McCartney has been a vegetarian for over 25 years. He co-authored "The Meat Free Monday Cookbook," with his daughters Mary and Stella. Photo: Kevin Winter / 2012 Getty Images

Image 32 of 48 After struggling with low-energy, actress Fran Drescher overhauled her diet opting to live a vegan and gluten-free lifestyle. After struggling with low-energy, actress Fran Drescher overhauled her diet opting to live a vegan and gluten-free lifestyle. Photo: Alexandra Wyman / Getty Images

Image 33 of 48 Prince was a vegan for years, but he's now a vegetarian. Prince was a vegan for years, but he's now a vegetarian. Photo: Stuart Wilson / Getty Images

Image 34 of 48 Basketball player Raja Bell has been a vegetarian since he was 2 years old (he only eats cheese occasionally, according to a Washington Post article). Basketball player Raja Bell has been a vegetarian since he was 2 years old (he only eats cheese occasionally, according to a Washington Post article). Photo: Ronald Martinez / Getty Images

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Image 36 of 48 Hip-hop mogul Russell Simmons has been a vegan since 1998. Hip-hop mogul Russell Simmons has been a vegan since 1998. Photo: Stephen Lovekin / Getty Images

Image 37 of 48 Musician Shania Twain was the first celebrity to earn the Sexiest Vegetarian Alive honor, in 2011. She says she hasn't eaten meat since 1993. Musician Shania Twain was the first celebrity to earn the Sexiest Vegetarian Alive honor, in 2011. She says she hasn't eaten meat since 1993. Photo: Jason Merritt / Getty Images

Image 38 of 48 A lifelong vegetarian (she is the daughter of Linda and Paul McCartney, after all), designer Stella McCartney doesn't use leather or fur in her collections. A lifelong vegetarian (she is the daughter of Linda and Paul McCartney, after all), designer Stella McCartney doesn't use leather or fur in her collections. Photo: Samir Hussein / Getty Images

Image 39 of 48 "Jackass" star Steve-O stopped eating meat after kicking drugs. He then gave up eggs, fish and dairy. "Jackass" star Steve-O stopped eating meat after kicking drugs. He then gave up eggs, fish and dairy. Photo: Christopher Polk / Getty Images

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Image 41 of 48 Indie musician Ted Leo of Ted Leo and the Pharmacists has been a vegetarian since 1988 and vegan since 1998. Indie musician Ted Leo of Ted Leo and the Pharmacists has been a vegetarian since 1988 and vegan since 1998. Photo: Cory Schwartz / Getty Images

Image 42 of 48 Former professional boxer and "The Hangover" actor Mike Tyson became a vegan because of a family history of obesity. He reportedly lost over 100 pounds after making the change. Former professional boxer and "The Hangover" actor Mike Tyson became a vegan because of a family history of obesity. He reportedly lost over 100 pounds after making the change. Photo: Frederick M. Brown / Getty Images

Image 43 of 48 After being diagnosed with the autoimmune disease Sjogren's Syndrome, professional tennis player Venus Williams switched to a raw, vegan diet. Her sister Serena Williams switched as well, for moral support. less After being diagnosed with the autoimmune disease Sjogren's Syndrome, professional tennis player Venus Williams switched to a raw, vegan diet. Her sister Serena Williams switched as well, for moral ... more Photo: Alberto E. Rodriguez / Getty Images

Image 44 of 48 Weird Al Yankovic has been a vegetarian (and sometimes vegan) since the 1990s. Weird Al Yankovic has been a vegetarian (and sometimes vegan) since the 1990s. Photo: Frederick M. Brown / Getty Images

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Image 46 of 48 "Bridesmaids" actress/writer Kristen Wiig took the title of Sexiest Celebrity Vegetarian in 2011. "Bridesmaids" actress/writer Kristen Wiig took the title of Sexiest Celebrity Vegetarian in 2011. Photo: Cindy Ord / Getty Images

Image 47 of 48 Actor Woody Harrelson has been vegan for over 25 years. Actor Woody Harrelson has been vegan for over 25 years. Photo: Alberto E. Rodriguez / Getty Images