"Anti-aging" supplement NAD+ has been drawing massive attention from beauty enthusiasts after multiple experts and celebrities started endorsing it. 

NAD+, short for nicotinamide adenine dinucleotide, is a coenzyme that helps boost metabolism, help repair DNA, improve immunity, and ensure longevity. 

It is currently available in the form of an IV drip or through injection, and numerous stars -- inclulding Jennifer Aniston and Hailey Bieber -- have promoted it for its alleged anti-aging effects, such as rejuvenating the skin. 

Biochemist Charles Brenner explained in an interview with Business Insider the vital role played by NAD+ in the body, saying, "NAD coenzymes are the central catalysts of all living things."

Brenner added: "They underlie the conversion of protein, fat, and carbohydrate into energy. They underlie the conversion of everything that we eat into everything that we do and everything that we are. They are required for our cells to generate energy."

 NAD supplement company ChromaDex's CEO Robert Fried also testified that this supplement is beneficial for boosting "resiliency" when tired or sick.

Along with these experts, celebrities have touted NAD+ for its positive results.

In a YouTube video posted on the Evolve Healthcare channel, Bieber and pal Kendall Jenner received NAD+ through IV drip.

"I’m going to NAD for the rest of my life, and I’m never going to age," Bieber claimed.

Podcaster Joe Rogan is also a fan, and Aniston has revealed that she takes NAD+ and even called it, "the future," during her interview with Wall Street Journal.

Amid the surge in NAD+ endorsements, Google searches for the supplement are expected to take off by 10% next year, and clinics and the market for the therapy are also predicted to see a spike in its demand. 

It should be noted that NAD+ supplements aren't FDA-approved; hence, they are not regulated. Some experts also claimed that they are rather "useless" -- contrary to the claim that they give anti-aging results. 

Professor and NAD researcher Dr. Shin-ichiro Imai from Washington University School of Medicine in St. Louis told the New York Post: “Unfortunately, NAD itself is not as effective as other compounds. It’s big and it cannot actually easily go into cells. And also, if you take NAD orally, your gut bacteria basically consume NAD completely."