Noted British psychiatric researcher Malcolm Peet conducted a provocative cross-cultural analysis of the relationship between diet and mental illness. His primary finding was a strong link between high sugar consumption and the risk of both depression and schizophrenia.
There are at least two potential mechanisms through which refined sugar intake could exert a toxic effect on mental health. First, sugar actually suppresses activitiy of a key growth hormone in the brain called BDNF. BDNF levels are critically low in both depression and schizophrenia.
Second, sugar consumption triggers a cascade of chemical reactions in your body that promote chronic inflammation. In the long term, inflammation disrupts the normal functioning of your immune system, and wreaks havoc on our brain. Once again, it’s linked to a greater risk of depression and schizophrenia.
Sources:
Psychology Today July 23, 2009
The British Journal of Psychiatry May 2004;184:404-8