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“Even patients in their 20s are experiencing symptoms of brain fog, fatigue, chronic inflammation, and chronic infection post-Covid,” Khan says. In its clinical experience, some have reported improvements in energy, mental clarity, migraines, and circadian disruption after using NAD-related treatments, especially during periods of high physical or cognitive stress.
“I have a lot of fitness enthusiasts (as patients), who recover better after injury or intense exercise,” Khan adds. “They feel like they can do more repetitions and swim more laps, and their tissues don’t fatigue as easily.”
Early research It also explores the role of NAD+ in neurodegenerative diseases, inflammatory pain pathways, and addiction, although much of this work is still preliminary. In people with existing degenerative conditions, such as Parkinson’s disease, muscular dystrophy, or… Alzheimer’s disease– NAD precursors may help slow deterioration. What’s still unclear is whether starting supplements can prevent disease or significantly alter the course of aging.
Safety, side effects and considerations
Among NAD+ enhancers, NR supplements have the strongest safety data. It has been studied in doses Ranging from 1000 to 3000 milligrams daily In healthy adults, with minimal or no reported side effects.
Although NMN has also been widely studied, it has been marginalized for years due to regulatory issues. In 2022the US Food and Drug Administration has stated that NMN cannot be sold as a supplement because it is being examined as a drug. This decision was later reversed In 2025.
Niacin, another NAD+ precursor, is effective but less popular because high doses can cause flushing, where the cheeks become red and warm, and increased heart rate due to vasodilation. Although this reaction is uncomfortable, it is generally not serious.
Animal studies Concerns have been raised that extremely high doses of NAD+ precursors can promote tumor growth, prompting doctors to be cautious in patients with active cancer. In practice, NAD supplementation is usually avoided during active malignancy and is considered on a case-by-case basis for those in long-term remission, often in consultation with an oncologist.
Importantly, no human clinical trials have shown an increased risk of oral NAD precursors. Some researchers even hypothesize that NAD may support genetic stability and cancer control. “If you don’t have signs of malignancy or a strong family history of genetic syndromes like BRCA and breast cancer, I firmly believe that NAD+ is actually cancer-protective,” Khan says. However, long-term data are limited.
Pregnancy remains another gray area; Most doctors recommend avoiding NAD+ supplements during pregnancy due to a lack of safety data. However, according to Khan, “There is Some evidence NAD+ can support fertility leading to pregnancy, maintain egg quality, and sperm quality.
NAD+ precursors and IVs
Some products claim to deliver NAD+ directly, but physiologically, this is unlikely to work when taken orally. NAD+ itself has poor bioavailability and does not easily cross the digestive tract or enter cells. This is why most longevity experts recommend precursors that can be absorbed, transported into cells, and converted into NAD+ internally.
Intravenous medications and injectable NAD+ have risen in popularity, but evidence supporting their effectiveness is weak. There is no known transporter that transports NAD+ directly from the bloodstream into cells, which means that much of the injected molecule may be quickly broken down or excreted.