Theanti-aging supplement Kim Kardashian andBryan Johnson have in common its more effective than NAD+

This is 40-something.Kim Kardashian, 45, has tried to cling to her youth by undergoing skin-tightening treatments, traveling to Korea for stem cell therapy and even getting injected with salmon sperm in her visage.Biohacker Bryan Johnson, 48, has worked to stave off death with an extreme protocol that includes five sessions of hyperbaric oxygen therapy a week, shockwave therapy thrice weekly and an 18-hour fasting schedule.Besides frustrating changes to their hormones, muscle mass and skin, quadragenarians like Kardashian and Johnson also have to worry about a drop in their nicotinamide adenine dinucleotide (NAD⁺) levels.Found in all living cells, the molecule plays a key role in cellular energy production, mitochondrial function, DNA repair and metabolism.“NAD⁺ levels naturally decline with age, most significantly in the 40s, [contributing to] chronic inflammation, poor sleep, metabolic disease and prolonged stress,” Dr.Pooja Gidwani, a double board-certified internal and obesity medicine physician based in LA, told The Post.That’s why Kardashian and Johnson have turned to nicotinamide mononucleotide (NMN) oral supplements to boost their NAD⁺ levels.Here’s how NMN works in the body — and why it’s often better than NAD⁺ supplementation.NMN is a form of vitamin B3 that’s absorbed rapidly in the gut and converted into NAD⁺ while inside cells.By supporting NAD⁺ levels, NMN may improve mitochondrial energy production, insulin sensitivity, muscle function and vascular health.“Clinically, any benefits tend to show up as improved energy regulation, exercise tolerance or metabolic markers rather than dramatic cosmetic or weight-loss effects,” Gidwani said.NAD⁺ levels can be measured with specialized blood tests.An NMN dose often ranges from 250 to 500 milligrams, Gidwani said, perhaps even going up to 1,000 mg.

How and when you take the supplement is important.“NMN is typically taken in the morning, as increasing cellular energy later in t...