NMN (Nicotinamide Mononucleotide)

NMN is a 6.0–6.5/10 fit for older or metabolically strained adults who want an NAD+ precursor trial with measured endpoints, not a reliable anti-aging shortcut for already healthy adults. The cleanest evidence anchors are Zhang 2024, which found NAD levels rose while broad glucose and lipid outcomes stayed limited, and Yoshino 2021, which reported a 25% muscle insulin-sensitivity gain in prediabetic postmenopausal women. Igarashi 2022 adds useful context: found NAD+ elevation and selected physical-function changes in older men. The practical gap is the same one that shows up across the report: mechanism and early outcomes are more convincing than broad real-world certainty. In practice, NMN belongs after the basics, works best when the target is specific, and deserves tracking around benefits, side effects, interactions, and cost before it becomes a standing protocol.

✅ Best for: Adults over 40 with likely NAD+ decline, especially those with insulin resistance, higher BMI, declining physical function, low training volume, or poor lifestyle NAD+ inputs. NMN makes the most sense after the foundations are in place: resistance training, aerobic work, sleep regularity, protein adequacy, metabolic health, sauna or heat, and fasting rhythm. It is also reasonable for self-quantifiers willing to track fasting insulin, HbA1c, blood pressure, subjective energy, and training capacity over an 8-12 week trial.

❌ Avoid if: You have active cancer, are on PARP inhibitor therapy, are pregnant, breastfeeding, under 18, or have complex oncology history without clinician oversight. Avoid NMN if you need guideline-backed diabetes, hypertension, sarcopenia, or cardiovascular care, because no major medical society recommends NMN as treatment. Also skip it if $60-100/month would displace higher-confidence basics, if you expect same-week energy transformation, or if your lifestyle already gives you strong NAD+ support and you are chasing marginal gains.