I found this article on excitotoxins and it talks about how they are causing all types of issues in humans, including endocrine disorders, autism, etc. Scarey stuff! I am becoming a firm believer and am in the process of trying to adopt clean eating habits:
Here's a paragraph from the article
"Different people will have differing reactions to excitotoxins. Some “lucky” folks have the ability to detoxify them from the body and see little or no reaction. I find that most people will see some reaction, so keep on the look out for how you feel and what you ate. Very high intake of any excitotoxin can lead to abnormal learning, addictive behaviors, behavioral and emotional issues and even affect the endocrine systems in children. When animals are fed MSG early in life, they can develop short stature, small endocrine organs pituitary, adrenal glands, thyroid gland, ovaries, testes and pancreas) and a high risk of seizures. Some of these effects are reversible, some are permanent."
http://www.drjoeesposito.com/articals/excitotoxins.html
Here's a link to another article which also suggests supplements to help combat the the negative effects of these excitotoxins:
http://insuranceandwellness.com/Excitotoxins.pdf