There are countless other interesting studies - and untested hypotheses - on the complex interactions between food and mood. Although some findings are well-established, many remain controversial and require further research. In the meantime, there is no harm in doing some experimenting of your own (just make sure to talk to your doctor before making any major dietary changes).
Food & Mood: The Complete Guide to Eating Well and Feeling your Best, by Elizabeth Somer. There is also a cookbook.
Your Brain on Food: How Chemicals Control Your Thoughts and Feelings, by Gary Wenk
Brain foods: The effects of nutrients on brain function. Neuroscientist Fernando Gomez-Pinilla reviews research on the brain mechanisms linking diet to mental function.
Conklin, S., Gianaros, P., Brown, S., Yao, J., Hariri, A., Manuck, S., & Muldoon, M. (2007). Long-chain omega-3 fatty acid intake is associated positively with corticolimbic gray matter volume in healthy adults Neuroscience Letters, 421 (3), 209-212 DOI: 10.1016/j.neulet.2007.04.086
Siepmann, T., Roofeh, J., Kiefer, F., & Edelson, D. (2011). Hypogonadism and erectile dysfunction associated with soy product consumption Nutrition, 27 (7-8), 859-862 DOI: 10.1016/j.nut.2010.10.018
Wurtman RJ, & Wurtman JJ (1996). Brain Serotonin, Carbohydrate-craving, obesity and depression. Advances in experimental medicine and biology, 398, 35-41 PMID: 9045545