Biohacker Bryan Johnson, 48, has worked to stave off death with an extreme protocol<\/a> that includes five sessions of hyperbaric oxygen therapy a week, shockwave therapy<\/a> thrice weekly and an 18-hour fasting schedule.<\/p>\n 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.<\/p>\n Found in all living cells, the molecule plays a key role in cellular energy production, mitochondrial function, DNA repair and metabolism.<\/p>\n \u201cNAD\u207a levels naturally decline with age, most significantly in the 40s, [contributing to] chronic inflammation, poor sleep, metabolic disease and prolonged stress,\u201d Dr. Pooja Gidwani<\/a>, a double board-certified internal and obesity medicine physician based in Los Angeles, told The Post.<\/p>\n That\u2019s why Kardashian<\/a> and Johnson<\/a> have turned to nicotinamide mononucleotide (NMN) oral supplements<\/a> to boost their NAD+ levels.<\/p>\n Here\u2019s how NMN works in the body \u2014 and why it\u2019s often better than NAD+ supplementation<\/a>.<\/p>\n What is NMN?<\/p>\n NMN is a form of vitamin B3 that\u2019s absorbed rapidly in the gut and converted into NAD+ while inside cells.<\/p>\n By supporting NAD+ levels, NMN may improve mitochondrial energy production, insulin sensitivity, muscle function and vascular health.<\/p>\n \u201cClinically, any benefits tend to show up as improved energy regulation, exercise tolerance or metabolic markers rather than dramatic cosmetic or weight-loss effects,\u201d Gidwani said.<\/p>\n How do you start NMN supplementation?<\/p>\n NAD+ levels can be measured with specialized blood tests.<\/p>\n 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.<\/p>\n \u201cNMN is typically taken in the morning, as increasing cellular energy later in the day may interfere with sleep for some individuals,\u201d Gidwani added.<\/p>\n \u201cNMN appears to be most effective when used alongside foundational lifestyle factors, including adequate sleep, regular physical activity, sufficient protein intake and overall metabolic health optimization.\u201d<\/p>\n It tends to be most useful for older adults or metabolically stressed people who are already making these lifestyle changes, Gidwani said.<\/p>\n She noted that the most meaningful benefits of NMN are generally gradual and cumulative, developing over weeks to months of consistent supplementation.<\/p>\n Are there any downsides to NMN supplements?<\/p>\n \u201cShort-term human studies<\/a> suggest NMN is generally well-tolerated, but long-term safety data are still limited,\u201d Gidwani said.<\/p>\n \u201cReported side effects are usually mild and may include gastrointestinal discomfort, headaches or sleep disturbances, particularly at higher doses or when taken later in the day.\u201d<\/p>\n One potential issue is that NMN products vary widely in purity, potency and stability, which is why third-party testing and reputable sourcing are key.<\/p>\n The Food and Drug Administration does not regulate supplements the same way it regulates prescription drugs.<\/p>\n And NMN is not for everyone.<\/p>\n It should be used cautiously or avoided altogether by people being treated for cancer and pregnant or breastfeeding women.<\/p>\n \u201cIndividuals with complex medical conditions or those on multiple medications should discuss NMN use with a physician before starting supplementation,\u201d Gidwani said.<\/p>\n How does NMN compare to NAD+ supplementation?<\/p>\n \u201cNMN, as a precursor, is smaller, more bioavailable and readily converted inside cells into NAD\u207a, making it a more effective oral approach,\u201d Gidwani noted.<\/p>\n NAD+, in contrast, is a large molecule that cannot directly penetrate cell membranes. That\u2019s why it\u2019s typically administered via IV infusion<\/a> or injection to bypass the digestive system.<\/p>\n Patients often experience intense, immediate effects from an NAD+ IV, while NMN users may notice subtle changes within hours, such as improved mental clarity or energy, particularly\u00a0if baseline NAD+ levels are low.<\/p>\n Still, taking an NMN capsule or powder is \u201cfar more practical\u201d for long-term use, Gidwani said.<\/p>\n \u201cNAD\u207a IV therapy is expensive, time-consuming and often associated with side effects such as nausea, flushing, chest tightness or anxiety during infusion,\u201d she added.<\/p>\n \u201cFrom a cost, convenience and adherence perspective, NMN is generally a more accessible option,\u201d she said.<\/p>\n Before you stock up on NMN \u2026<\/p>\n Gidwani emphasized that NMN \u201cmay help optimize cellular energy pathways in the right context,\u201d but it\u2019s \u201cnot a miracle anti-aging drug,\u201d nor can it replace sleep, exercise, nutrition or medical care. <\/p>\n \u201cThe goal of NMN supplementation is not to \u2018supercharge\u2019 the system, but to support normal cellular processes that become less efficient over time,\u201d she said.<\/p>\n \t\t\t\t\t\t\t\t![\"Bryan](\"https:\/\/www.europesays.com\/uk\/wp-content\/uploads\/2026\/01\/eccentric-billionaire-obsessed-living-forever-21751978.jpg\")
Biohacker Bryan Johnson is trying literally everything to not die. He\u2019s shown here getting a laser treatment to his face. Instagram\/@bryanjohnson_<\/p>\n![\"A](\"https:\/\/www.europesays.com\/uk\/wp-content\/uploads\/2026\/01\/nicotinamide-mononucleotide-powder-used-support-119826900.jpg\")
<\/a>Nicotinamide mononucleotide is a form of vitamin B3 that\u2019s absorbed rapidly in the gut and converted into nicotinamide adenine dinucleotide while inside cells. Cloudy Design \u2013 stock.adobe.com<\/p>\n![\"Illustration](\"https:\/\/www.europesays.com\/uk\/wp-content\/uploads\/2026\/01\/119826447.jpg\")
NAD+ is crucial for converting food into energy, repairing damaged DNA and regulating cell survival. designua \u2013 stock.adobe.com<\/p>\n