Been reading about it. Makes sense. There are ACE2 receptors in the brain and we have been noticing neurological problems associated with COVID-19 - some that can last long after a patient is supposedly no longer infected. Endothelial dysfunction as well is associated with COVID and possibly a big reason for the myriad of symptomology with COVID.  Glutathione is another one of those substances that we are deficient in that cannot be cleaned up by diet alone. It is protective for the brain. Even organics are deficient in key nutrients any more. All the excito-toxins in the environment, like MSG, deplete Glutathione. When someone is sick with COVID, the brain's immune system kicks in and increases Glutamine levels - which depletes already low Glutathione. This is why they add Glutamine compounds to vaccines - in order to stimulate the immune system - especially the brain. The problem is that these Glutamine levels in some people never come down - think Autism. They have tested people in their thirties with Autism Spectrum Disorders and found Glutamine levels that are the same as someone who just received a vaccine.  Elevated Glutamine is part of the reason behind why it is hard to think when sick - like Cold head. Imagine being like that all the time. Glutathione counterbalances the Glutamine but our modern lives have thrown the system completely out of balance.  NAC is a good way to get levels up as well as avoiding vaccines and eating or drinking anything that contains neurotoxic substances. Manufacturers have gotten real slick at hiding these substances in the products they make and not listing it as MSG. You can find lists online of these names that contain Glutamine type compounds. It can be a daunting task to keep them out of the diet when consuming manufactured food. If it is processed, you probably shouldn't eat it. Thanks for the heads up.