Great points, and thanks for reading and commenting! Yes, L-methionine is the natural stereoisomer. And yes, good point that homocysteine, downstream of L-methionine in the transsulfuration pathway, is deleterious. Here are 2 reviews on the health effects of methionine: https://pubmed.ncbi.nlm.nih.gov/31515518/ (subscription required) and https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9508608/ -- but you are right that as Paracelsus said, the dose makes the poison, in that too much or too little is harmful.