Bernie Sanders' run for president isn't the first time the Democrat has made headlines running: In high school, he was a track star. Sanders remains active at the age of 74, and clips of him playing baseball, hockey, basketball, and tennis can be found on the internet.

Sanders seems to be in vigorous health, apparently from good health habits he's maintained throughout his life, says Dr. David Brownstein, holistic doctor and author of the newsletter Dr. Brownstein's Natural Way to Health, who says that age alone shouldn't keep Sanders from being an effective president.

"I don't think age should limit you if you're healthy and energetic," Dr. Brownstein tells Newsmax Health. "I'm not surprised that a 74-year-old man is running for president. If you take care of yourself, you should be able to do what you want to do at his age."

According to an article in People magazine, Sanders eats mostly meat and vegetables. "He was Paleo before Paleo was a thing," his stepdaughter Carina Driscoll told People.

"Sanders appears to be mainly eating a healthy diet free of refined sugar, salt, flour and oil since he's reported to eat basically a Paleo diet," says Dr. Brownstein.

Along with being active and eating well, Sanders is also passionate about his work — all things that Dr. Brownstein says are components of a healthy old age.

Sanders' keen interest in athletics goes as far back as elementary school, and his pride in his accomplishments is evident. "I was a very good athlete," Sanders told CNN. "I was a pretty good basketball player. My elementary school in Brooklyn won the borough championship — hardly worth mentioning, but we did. And, yes, I did take third place in the New York City indoor one-mile race.

"I was a very good long-distance runner — not a great runner, but I was captain of my cross-country team, won a lot of cross-country meets and certainly won a lot of races."

Even so, Sanders hasn't been free of medical problems. He's been diagnosed with a variety of ills over the years, including gout, diverticulitis, back pain, underactive thyroid gland (hypothyroidism), acid reflux, hernias, superficial skin cancers, and a cyst on his vocal cords.

"All appear relatively minor," says Dr. Brownstein. "Gout is a minor road bump for most people. His hypothyroidism appears to be well-treated, and a properly balanced thyroid gland can give you lots of energy into your older years.

"From his activity level, it seems that his thyroid is properly balanced," he said. "That's going to help give him the energy he needs if he becomes president."

Congressional physician Brian P. Monahan, who has treated the Vermont senator more than 20 years, wrote that Sanders is in "very good health," and has normal blood pressure and no history of cardiovascular disease.

"You are in overall very good health and active in your professional work, and recreational lifestyle without limitation," Dr. Monahan continued.

"We've elected other older men," said Dr. Brownstein. "Ronald Reagan was 69 when he took office. I would not have a problem simply with a candidate's age if he was in good enough shape otherwise, which Sanders appears to be.

"Bernie Sanders is a great example for all of the baby boomers."