To get back to the original subject:
While it's true that Ca deficiency and estrogen decline can't explain all of the age-related risk of osteo, NAD+ decline clearly can't be the main factor. Osteoporosis begins earlier, proceeds more quickly, and is far more severe in women than in men, yet the decline with age of NAD+ is substantially more steep in men than in women (correlation between age and NAD+ levels r =-0.706 vs. -0.537, respectively, at least in sun-protected skin, which is the only place for which we have gender-specific human data(1)). In C57BL/6J mice, liver NAD+ levels at 23–24 months of age are non-significantly higher in males than females (≈0.65 vs. 0.60 nmol/mg protein, respectively).(2)
The NR hate on this forum is becoming outrageous. I think it stems from certain people who want to NMN to become a prescription drug costing thousands of dollars.
Come now. Cite a single instance of "NR hate." NR caution? NR skepticism? Sure.
References
1: Massudi H, Grant R, Braidy N, Guest J, Farnsworth B, Guillemin GJ. Age-associated changes in oxidative stress and NAD+ metabolism in human tissue. PLoS One. 2012;7(7):e42357. doi: 10.1371/journal.pone.0042357. Epub 2012 Jul 27. PubMed PMID: 22848760; PubMed Central PMCID: PMC3407129.
2: Mitchell SJ, Madrigal-Matute J, Scheibye-Knudsen M, Fang E, Aon M, González-Reyes JA, Cortassa S, Kaushik S, Gonzalez-Freire M, Patel B, Wahl D, Ali A, Calvo-Rubio M, Burón MI, Guiterrez V, Ward TM, Palacios HH, Cai H, Frederick DW, Hine C, Broeskamp F, Habering L, Dawson J, Beasley TM, Wan J, Ikeno Y, Hubbard G, Becker KG, Zhang Y, Bohr VA, Longo DL, Navas P, Ferrucci L, Sinclair DA, Cohen P, Egan JM, Mitchell JR, Baur JA, Allison DB, Anson RM, Villalba JM, Madeo F, Cuervo AM, Pearson KJ, Ingram DK, Bernier M, de Cabo R. Effects of Sex, Strain, and Energy Intake on Hallmarks of Aging in Mice. Cell Metab. 2016 Jun 14;23(6):1093-1112. doi: 10.1016/j.cmet.2016.05.027. PubMed PMID: 27304509; PubMed Central PMCID: PMC4911707.