Dr. Mehmet Oz dipped his spoon into a bowl of yogurt and fruit, scooped up some blueberries, and proclaimed his breakfast to be an ideal blend of calcium, protein, and potent antioxidants.

The cardiac surgeon, best known for making frequent appearances on “The Oprah Winfrey Show,” was touting the benefits of eating a healthy breakfast during a recent interview in his office. As the director of the Cardiovascular Institute at NewYork-Presbyterian Hospital and author of several books on personal health, Dr. Oz has staked his career on educating the public about the virtues of healthy eating and exercise.

Now, the doctor is seeking to improve the breakfast habits of New York City schoolchildren. The city’s Department of Education offers a federally subsidized breakfast program, but Dr. Oz envisions a healthier menu that would put fiber-rich cereal on food trays, along with 2% milk and sliced apples. He also wants breakfast served in classrooms instead of in lunchrooms and auditoriums.

In making his case, Dr. Oz compared the nutritional value of a healthy breakfast to that of sugary foods and soda. When students eat the latter, he said, “Two hours later, you’re hypoglycemic and you can’t pay attention in class and you starve, waiting for lunch to come.”

So far, he conceded, the project is in its nascent stages. “We’re not quite there yet,” he said, his television-ready smile fading momentarily.

Dressed in blue scrubs and clogs, Dr. Oz leads by example. An early riser, he begins the day with a few yoga poses and 100 push-ups. He typically arrives at his office by 6:20 a.m., and then divides his day between surgical cases, administrative duties, and “media stuff,” he said. Every other week, he flies to Chicago to tape two segments for Ms. Winfrey’s show. They have covered a range of topics, including hypnosis and obsessive-compulsive disorder.

“I live on surgical standard time, so if one part of the puzzle falls apart, the rest suffers,” he said.

When it comes to food, Dr. Oz rarely deviates from a carefully balanced diet. For lunch, he eats raw food or vegan dishes, and he enjoys a light supper around 5 p.m. He keeps economy-size bags of nuts in his office, which is adorned with press clippings and photographs of his family. A plump grapefruit sits on his desk. “Dessert is biological suicide,” Dr. Oz said.

At 47, Dr. Oz weighs 183 pounds, about 20 pounds lighter than his fighting weight of 205, which he maintained as a college football player.

A graduate of Harvard University, Dr. Oz earned joint medical and business degrees from the University of Pennsylvania in 1986. He completed his medical training at NewYork-Presbyterian Hospital/Columbia University Medical Center. He is a professor of surgery at Columbia, and he serves as vice chairman of cardiovascular services in the department of surgery. In addition to directing the hospital’s cardiovascular institute, he is the founder and director of a complementary medicine program there.

Dr. Oz is also the author of several books on personal health. In October, he published “YOU: Staying Young,” a guide to aging gracefully, which he penned with Dr. Michael Roizen. At home in Cliffside Park, N.J., his mission has had an impact on his four children, including his eldest daughter, Daphne, who in 2006 wrote a book for college students, “The Dorm Room Diet.”

Dr. Oz pulled a copy of her book from the shelf and proudly disclosed that his daughter refused his help. “She said I’d ruin it,” he joked.

The son of a physician, Dr. Oz — whose parents are from Turkey — said medicine was an early calling. “It is very difficult for me to watch someone else suffer,” he said.

His attraction to cardiac surgery stemmed from a fascination with the inner workings of the human body and the demands of a surgical specialty, like the ability to make quick decisions and to maintain physical endurance in the operating room.

Fueled by the operating room experience, Dr. Oz has made it his mission to educate people on ways to avoid cardiovascular disease. “When I see foods, I see drugs,” he said, referring to the processed foods many people consume.

He said he has focused on food as a public health issue because it is ubiquitous. “Everyone is affected by food,” he said. Despite public health efforts, he said he found that many patients were still uneducated. “After you do it a couple hundred times, you realize they don’t know this,” he said.

In an effort to influence the eating and exercise habits of young people, Dr. Oz founded a health education program for high school students, HealthCorps, several years ago. With $2 million in funding from the New York City Council, HealthCorps educators run programs in 28 schools citywide, teaching students about diet, nutrition, and exercise.

Targeting children represents a specific strategy.

“When you teach high school kids something, you get a multiplier benefit. They audit their refrigerators,” he said, describing a teenager foraging for a snack. “I recognized that these kids, not only do they get it, they talk about it.”