DENVER -- A Colorado doctor has invented a supplement that he says slows the aging process and could possibly prevent diseases. The pill is called Protandim, a natural supplement that he claims can change the chemistry of the body.

The supplement makes you healthier, but you don't feel any changes, said Protandim's manufacturer.

One of the trial participants 7NEWS spoke with said that besides a slight peak in energy, he didn't notice any changes. But Leigh Severance swears by this new "anti-aging" pill. He said he'll take it until the day he dies but jokes that if the pill really works, he'll be around for a long time.

Severance is 66 years old, partially retired and lives on a golf course. But he said, on the inside he's really 22 years old. But he doesn't attribute his youthful feeling to a midlife crisis or his Porsche.

Severance is taking Protandim, an antioxidant supplement he says eliminates age-related oxidative stress. Oxidative stress is when you have too many free radicals in your system and not enough antioxidants.

"When you have too many oxidants, cells become damaged, all of the main classes of molecules get oxidized and damaged," said Dr. Joe McCord said.

McCord, who is with the University of Colorado Health Sciences Center, formulated Protandim.

"Oxidative stress is probably the main biochemical marker of the aging process, So if want to know how old an organism is, you can measure oxidative stress level and it will give you an idea," said McCord.

He said the pill can lower that level of oxidative stress by revving up your natural antioxidants. And that, in turn, makes people like Severance 22 years old, McCord said.

Or at least when it comes to his oxidative stress levels.

"It's getting rid of millions of free radicals," said Severance. He hopes it's helping him live longer.

"I've told my kids that they need to be taking it," he said.

McCord said oxidative stress often accompanies many diseases like cancer, diabetes and Alzheimer's disease. So now that he says his supplement helps healthy people, he plans on studying how it will affect those already suffering with diseases and how healthy people may be able to avoid getting sick in the future.

More Information:

Protandim is available online at Protandim.com or by calling (877) 682-6346 (1-8-Protandim)