According to The New York Times, Dr. Oz is "one of the most accomplished cardiothoracic surgeons of his generation." Over the course of his career, he has performed 5,000 open-heart surgeries, has successfully transplanted people's lungs and is just generally in the upper fraction of the top one-tenth of a percent of doctors you want standing over your split-open chest cavity in life-and-death situations. While that description would admittedly make a pretty badass business card, there's no way it would fit with all the other things he's accomplished, even if you only count stuff he did while I was taking naps.
Oz graduated from Harvard before moving over to the University of Pennsylvania, because they have the best business school in the world and he wanted to earn an MBA while going to medical school, in case the whole "being the world's best heart surgeon" thing didn't work out. He completed his five years' worth of schooling in three, which is the fastest time allowable before they start checking you for wires to make sure you're not a robot from the future.
It might seem like bad news that America lost its smartest doctor to the world of daytime TV, but it's not that simple. First of all, he didn't stop being a doctor. When he's not walking a middle-aged housewife through a gigantic model of her husband's swollen urethra on national television, Dr. Oz is still the acting director of the Cardiovascular Institute and Complementary Medicine Program at New York-Presbyterian Hospital, which you might recognize as one of the 10 best hospitals in the country. He spends most of his week writing and filming his show, but on Thursdays he can still be found performing complicated open-heart surgeries that take hours and require him to take people's lives in his hands.
"Occasionally I perform them with my penis, just to keep things interesting."