David Sinclair of Harvard University has been working toward a molecular fountain of youth. Finding previous success in mice, early human trials have begun in small studies around the globe. Preliminary results of these studies indicate that the treatments are safe and do not induce major adverse side effects, but it is still far too early to tell if the treatments will actually be effective at reversing aging in humans.

A normal part of human aging involves senescence, which is a general wearing out of the body over time. Muscles begin to lose tone and become inflamed over time, and they also can develop insulin resistance. Without being able to use insulin, the cells aren’t able to uptake the glucose needed for activity. These problems contribute to why many elderly people have trouble getting around and athletes aren’t able to sustain certain levels of activity as they age.

Last December, Sinclair’s group published a paper in Cell revealing that they had been able to drastically reduce the functional “age” of muscle tissue. Treating the mice with the metabolic co-enzyme NAD+ effectively reversed the aging process within the skeletal muscle by increasing muscle tone and producing effects similar to eating a healthy diet and exercising.

Over time, NAD+ levels decrease, which limits the cells’ ability to produce ATP in the mitochondria for energy. As the mice grew older and less active, their levels of NAD+ had basically been cut in half. By replenishing this critical compound in the mice, their muscles had been rejuvenated. The natural process that deteriorates skeletal muscle is the same one that affects the heart.

If the relative effects that were seen in the mice could be replicated in humans, it would result in a 60-year-old with the physique of a 20-year-old. The human studies that began this year following a period of financial uncertainty are initially only auditing the treatment’s safety, by taking stock of all side effects that could occur and identify negative interactions with other medications. The first studies have been fairly small, but will continue to grow.

Results from human studies that explore the treatment’s efficacy will not appear for a few more years, though Sinclair is optimistic. He told ABC that this treatment has the potential to allow individuals to lead long, healthy lives. He described the potential of his anti-aging therapy to one day be regarded similarly and ubiquitously as antibiotics.

"Some people say it's like playing God, but if you ask somebody 100 years ago, what about antibiotics? They probably would have said the same thing," he told ABC’s Sue Lannin. "Some people worry about big advances in technology and medicine, but once it's adapted and it's natural for people to live until they're 90 in a healthy way ... we'll look back at today like we do at the times before antibiotics when people died from an infected splinter."