…NMN is mainly located in the nucleus, mitochondria and cytoplasm, whereas in the human body, it can be found in placenta tissue and body fluids such as blood and urine [9]. It is naturally found in a variety of fruits and vegetables including immature soybean pods, cabbage, cucumber, broccoli, tomato, mushroom and avocado as well as in raw beef and shrimp. The NMN content in these vegetables and fruits are 0.25–1.88 mg/100 g and 0.26–1.60 mg/100 g, respectively, whereas raw beef and shrimp contain comparatively lower level of NMN than those plant-based food (0.06–0.42 mg/100 g). Based on the evidence of the presence of NMN in red blood cells, it has been put forward that physiologically pertinent NMN contents, which are required for the biosynthesis of NAD+ and many physiological functions, are absorbed from daily food sources [10].
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Good overview of NMN, what is known and what is not. US FDA has taken NMN off the market due to legal niceties, which sound dubious especially in light of FDA’s awful reputation (“…the term ‘dietary supplement’ does not include an article authorized for investigation as a new drug…” link). Not sure if NMN is available in other countries. The article linked above is well-worth perusing if you are using or considering this as a supplement. ABN
American Buddhist Net 