Quercetin- Inhibits glutamate release and is found in onion (highest in red onion), raw chili peppers, asparagus, kale, berries, plums, peppers, broccoli, sophora japonica leaf/flowers. However, we have also used this supplement. “These results suggest that quercetin inhibits glutamate release from rat cortical synaptosomes and this effect is linked to a decrease in presynaptic voltage-dependent Ca(2+) entry and to the suppression of PKC and PKA activity.” https://www.ncbi.nlm.nih.gov/pubmed/23933436 Protective effects of onion-derived quercetin on glutamate-mediated hippocampal neuronal cell death “This is the first report on the detailed mechanisms of the protective effect of quercetin on HT22 cells. Onion extract [...]