Dubbed the "holy grail of supplements," NAD+ is being enthusiastically embraced by Hollywood stars like Hailey Bieber, Jennifer Aniston, and Gwyneth Paltrow.

"I'm going to 'NAD+' for the rest of my life and never age," Hailey Bieber declared to Kendall Jenner in 2022's The Kardashians while both were receiving NAD+ infusions. In his documentary, Seasons, Justin Bieber filmed himself receiving NAD+ at a clinic to "flush out toxins".

Jennifer Aniston praised the power of weekly NAD+ injections in the Wall Street Journal, "I truly believe it’s the future," she said.

But what is NAD+, and why is it considered the key to extending lifespan and preserving health?

NAD+ is a vital coenzyme, crucial for a range of bodily functions, from energy production to DNA repair and cell survival. It acts as a "helper" for other enzymes, especially sirtuins and PARPs, which are directly involved in DNA repair and inflammation control. Without NAD+, the cell's "power plants" (mitochondria) can't function efficiently, leading to poor energy production and an increase in harmful free radicals.

Research indicates that NAD+ levels (the active form of NAD) significantly decline with age. "If you compare a 60-year-old to a 20-year-old, there's about a 50% reduction in NAD+ levels," explained Dr. Leonard Guarente, Novartis Professor of Biology at MIT and co-founder of Elysium Health.

This decline is a primary reason for the onset of aging symptoms, including fatigue, cognitive decline, and increased disease risk. This natural decrease has fueled a multi-billion dollar industry focused on restoring and maintaining NAD+ levels.

There are various ways to supplement NAD+, but the most common are through precursors like NMN (nicotinamide mononucleotide) and NR (nicotinamide riboside). Instead of directly absorbing NAD+ (due to poor bodily absorption), these precursors are used so the body can convert them into NAD+. Both NMN and NR are forms of vitamin B3 and are found in certain foods, albeit in small amounts.

Today, NAD+ is available at many luxury destinations. The Four Seasons Resort Maui offers infusions while guests relax under soft blankets, enjoying paradise views. The Modern Age clinic in New York City offers NAD+ in a cozy space designed by architect Madelynn Ringo.

However, even leading longevity experts disagree on the optimal NAD+ supplementation method. Intravenous infusions are expensive (300-2,000 USD for 500 mg) and can be painful if administered quickly. Podcast host Joe Rogan once shared that when the infusion speed increased, it felt like his "insides were on fire".

Some experts believe NAD+ is too large for effective intravenous and injection delivery, and the effects may be short-lived. Dr. Guarente, who produces NAD+ supplements, expressed skepticism: "NAD doesn't get into cells. You need to take an NAD precursor"—referring to the five main chemicals that combine to form the NAD+ molecule, including NR (nicotinamide riboside) and NMN (nicotinamide mononucleotide).

Model Hailey Bieber uses NAD+. Photo: Reuters

Model Hailey Bieber uses NAD+. Photo: Reuters

Despite celebrity endorsements, medical experts offer cautionary perspectives. Daniel Puleston, an assistant professor at the Icahn School of Medicine, emphasizes that studies on NAD+ precursors have only shown them to be safe and capable of increasing NAD levels in the blood, but their overall health benefits remain unclear. Many studies found no significant benefits regarding metabolic performance, while others reported only modest improvements.

Determining NAD+ levels is also controversial. Some companies sell at-home testing kits, but experts like Puleston and Dr. Ayodele Oyeyemi warn there's no medical consensus on what constitutes "good" or "bad" NAD+ levels. Consequently, these kits may be unreliable.

Will Cole, a functional medicine expert, also emphasizes that there's no "magic pill" to solve all problems. He believes supporting NAD+ levels should be combined with healthy habits like weight training, proper nutrition, and comprehensive inflammation reduction.

Hoang Dung (NY Post, Elle)