Thanks for asking! The polyamines, including Spermidine, are created off of the urea cycle and increasing the urea cycle is dependent on lowering, or inhibiting Nitric Oxide Synthase. There are plenty of natural NOS inhibitors, like Black Tea and Ginger. This will mean instant of Arginine going to make Nitric Oxide it is instead shunted to the enzyme Arginase in the urea cycle. Arginase needs Manganese too increase function, so maybe mussels will help here since they are very high in manganese.

But we cannot stop here since this might just mean that you spin the urea cycle around and around. What we need to do is stimulate Orniothine Decarboxylase (ODC) to pull the ornithine out of the urea cycle to the polymaine pathway. ODC need B6 as a cofactor to increase activity so taking B6 or eating foods high in B6 will do well here.

Not that we have the ornithine going where it need we need to make sure we can turn it into spermidine by making sure we have enough of the coenzymes for those enzymes. The coenzyme here is SAMe.

And that's it. But be careful, because if you have messed up genetics like me you already make enough spermidine and it will cause great mental turmoil, even suicidal thoughts.

Here is the pathway: https://www.science.org/cms/10.1126/science.aan2788/asset/5e...

On mental illness and spermidine: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5293545/