Celebrities claim to have found the fountain of youth. 

NAD, a molecule produced naturally in the body, is being sold in pill, liquid and IV form and everyone from athletes, actors and models have come out in support of it. 

Joe Rogan, Hailey Bieber and Kourtney Kardashian are among the stars to say the product helps them feel more energized, youthful and healthy. 

And unlike other celeb fads, they might be onto something. 

Research in mice suggested that increasing the levels of NAD in the body can increase lifespan by eight percent. 

Nicotinamide adenine dinucleotide (NAD), is a molecule our body produces that helps create and protect DNA, generate energy and build new cells. 

It's a crucial support to most everything our body does. When we're young, our body is efficient at producing NAD. 

As people age, production slowly tapers - which studies suggest might be one of the reasons we tend to feel worse as we get older. 

But scientists caution that they have yet to design a NAD product that our body can use in the same way that it uses the NAD we produce naturally. 

Despite the skepticism, NAD supplements are being endorsed by A-listers. 

'I'm going to NAD for the rest of my life, and I'm never going to age,' model Hailey Bieber said in jest while getting an IV form of the product with Kendall Jenner.  

'I have more energy, I feel like really vibrant. I feel great,' Joe Rogan, former UFC fighter and mega-popular podcaster, said in a 2020 episode of his podcast. 

'This has so many benefits and I love it,' Kourtney Kardashian Barker shared in a 2023 Instagram, calling NAD the 'genetic key to longevity'. 

These treatments come with a price, and it is a wide range - depending on how you choose to take in the product and what company you choose to buy it from.

NAD+ Platinum by Quicksilver Scientific, Kourtney Kardashian's preferred brand, offers 100 milliliters of its liquid product for $84. 

Other brands, like Maripolio's, offers a 120 pack of soft gels for $39. Wellness LabsRx offers a 90 pack of soft gels for $24. 

If you're looking for an IV form of the drug, the treatments tend to cost anywhere between $500 to $2000. 

All of these treatments claim to work by adding more NAD to your body. In theory, this works, since NAD is important to everything our body does. 

'They [NAD molecules] underlie the conversion of everything that we eat into everything that we do and everything that we are,' Professor Charles Brenner, a biochemist at City of Hope research hospital in California who studies anti-aging, told Business Insider. 

So scientists began investigating if adding more NAD to our body could blunt aging. Early research was promising. 

Taking NAD precursors for more than a year increased mice lifespan by 8.5 percent, a 2023 study from Institute for Systems Biology found. 

Increasing NAD amounts in the body could stave off aging and it's associated problems, a 2015 review from Eric Verdin, an aging researcher at the University of California San Francisco suggested.  

But, Dr Verdin's research said, we still don't know how NAD supplement will work in the body. 

In the eight years since, science has made little progress in designing products that the body can actually use. 

Though NAD itself is useful, taking it in pill or IV doesn't always work. 

This is because the molecule is so big that when you take it in these forms, it might be difficult for it to get inside your cells. 

Instead, it passes through without affecting any changes - coming out in your pee. 

This makes NAD supplements, IVs and drinks as they currently are, 'pretty useless', Dr Sabine Donnai, a doctor who is researching the drug for a longevity clinic in London, told Business Insider. 

Instead of NAD supplements, scientists suggest that you should take supplements that your body can use at the raw ingredients to create NAD from within. 

This includes products like niacin, nicotinamide riboside, nicotinic acid and more. 

The studies that have been done on generating more NAD in humans have used these supplements instead of NAD, according to a 2024 paper from Northumbria University. 

Others suggest that the best way to get more NAD isn't from supplements at all - it's from keeping up a healthy diet and exercise routine. 

Foods like broccoli, meat, fish, nuts and fortified cereals and breads are particularly well-suited to generating NAD, Dr Donnai said. 

She suggested that it's probably only certain people with health conditions or particular age-related issues that could really benefit from NAD supplements. 

'I would personally never advise anybody to take anything at all until you've measured whether you actually need it,' she said.