Nicotinamide adenine dinucleotide: these three words could hold the secret to age-defying medicine, according to scientists.

NAD+ for short, this molecule is present in all living cells, and research suggests that it could be used to boost longevity. But what is it and will we be able to harness its apparent powers any time soon?

What is NAD+?

The molecule plays a key role in regulating how cells age and the body functions. Over the course of an animal's lifespan, levels of NAD+ drop.

"It's one of the most important molecules for life to exist, and without it, you're dead in 30 seconds," David Sinclair, co-director of the Paul F. Glenn Center for the Biology of Ageing at Harvard Medical School, told Time.

Is it really the real-life fountain of youth?

"NAD+ is the closest we've gotten to a fountain of youth," Sinclair told Time.

Scientists believe that NAD+ could be harnessed to mimic the effects of how the body responds to calorie restriction, without the side effects like starvation and reduced reproductive capacity. When we restrict our calorie intake, the body attempts to conserve resources and begins repairing itself and fighting free radicals.

Studies suggest that boosting NAD+ levels in mice make them live younger, and appear younger both physically and in terms of their behaviour.

A 2017 paper published in the journal Science showed that when NAD+ was added to the water of mice, their levels of the compound spiked significantly within a matter of hours. In around seven days, experts could not distinguish between the tissue of two-year-old and four-month-old mice.

When will it be available on the market?

Sinclair has already tried taking NMN, a compound that causes the body to create NAD+. And admitting he sounds like a "kook" and his findings are anecdotal, he said that his lipid profile has improved dramatically and he feels less fatigued, according to Harvard Magazine.

Eventually, Sinclair hopes to create an NAD+ pill approved by the US Food and Drug Administration (FDA).

A firm named Elysium is already selling a dietary supplement containing a NAD+ precursor. A randomised control trial by the firm in November 2017 published in Nature suggested that those who took a supplement of an NAD+ precursor saw the levels in their body rise over two months.

This piece previously stated that Elysium had not undergone clinical trials. That error has now been corrected.