Jay Z, Beyonce start vegan challenge for rapper's 44th birthday Jay Z and Beyonce are giving themselves the gift of health for the rapper's birthday. The musical power couple are challenging themselves to a 22-day vegan diet. The "Magna Carter Holy Grail" rapper, who turned 44 on Wednesday, made the announcement on his Life + Times blog Tuesday, letting fans know that he and his wife are undergoing a major lifestyle change in an effort to become more spiritual. Psychologists have said it takes 21 days to make or break a habit. On the 22nd day, you've found the way," he wrote. PHOTOS: Beyonce and Jay Z On December 3rd, one day before my 44th birthday I will embark on a 22 Days challenge to go completely vegan, or as I prefer to call it, plant-based!! This all began a few months back when a good friend and vegan challenged me to embrace a 'plant-based breakfast' every day. It was surprisingly easier on me than I thought ...  Is that good friend Gwyneth Paltrow, perchance? We're not sure. No matter, Forbes' top-earning couple is wealthy enough to figure out a way to make the diet extra-delicious. Some of the diet's health benefits include increased metabolism, cancer prevention, lower cholesterol, decreased blood pressure and reduced risk of diabetes, asthma attacks and heart disease, according to the 22 Days nutrition website. The Grammy Award-winning rapper also seems to believe that the change is rooted in the mysticism of numbers. So why now? There's something spiritual to me about it being my 44th birthday and the serendipity behind the number of days in this challenge; 22 (2+2=4) coupled with the fact that the challenge ends on Christmas day ... It just feels right!" he said. You'll recall, he and Beyonce also talked a big game about numbers when they got married on April 4, 2008. Both singers' birthdays land on the fourth of their respective birth months and, oddly enough, 4 + 4 = 8. Jay Z said to call it "a spiritual and physical cleanse." He added that he will post his progress on his blog and elicited advice from fans for recommendations on "great food spots" and to "please help out! Please ha. As for what happens after Dec. 25, he isn't sure. "I don't know what happens after Christmas," he wrote. A semi-vegan, a full plant-based diet? Or just a spiritual and physical challenge? We'll see ...  But he did end the post on this note: "P.S. B is also joining me." Indeed, B, 32, who is currently touring the world with "The Mrs. Carter Show," shared an Instagram photo collage of her meals on Wednesday, simply captioning the fare "#22dayveganchallenge." The menu for the diet's first day included vanilla chia pudding with 1 cup fresh berries for breakfast; crunchy red cabbage and green apple sesame slaw with 1 cup steamed, cubed sweet potato (or 1 small sweet potato, baked) for lunch, 1/4 cup hemp hummus with fresh vegetables (carrots, celery, romaine leaves, bell pepper, etc.) for an afternoon snack; black bean and quinoa salad with quick cumin dressing for dinner and dark chocolate for dessert. So now, we can't wait to hear Hova's lyrical take on hemp and seitan instead of Champagne and caviar.