I am currently finishing up NE103 Macronutrients. I learned that Protein is a major contributor to the development of Serotonin. Serotonin carries messages of mood to the brain and gut, its a neurotransmitter that directly contributes to mood, memory, ability to learn, appetite, arousal, aggression, impulse control, sleep, and hormones. A low level of Serotonin in the brain and gut plays a large factor in states of depression.
The amino acid that is responsible for building Serotonin is Tryptophan, which you can find in many foods - here is a great site for info on Tryptophan:http://www.whfoods.com/genpage.php?tname=nutrient&dbid=103#formindietarysupplements
There is a supplement called 5-HTP, shouldn't exceed 100mg per day. Usually Tryptophan needs other aminos such as Tyrosine, Methionine, Histidine and Leucine to cross the blood brain barrier but 5-HTP easily crosses the blood brain barrier to directly produce Serotonin. Before taking this supplement you should do extensive research to make sure it's right for you.
Also, Gaba (Gamma-Aminobutyric) is another amino acid that has a calming effect, the recommended dosage is 100mg per day and not to exceed 800mg per day.
If you are on any sort of anti-depressant then these supplements are not recommended.
For a more extensive understanding about mood regulation and amino acid therapy check out the book called "The Diet Cure" by Julia Ross, M.A., it's an excellent resource - this book is included in the NE program - on page 117 begins a whole section on Refueling Your Brain Chemistry with Amino Acids.
On the CDs for NE103 Ed Bauman suggests a morning drink that will increase energy, stabilize blood sugar metabolism and improve healing. Since low energy is a side effect of depression this might be helpful for your days energy and stamina:
In Cranberry Juice (if you don't like cranberry it's no problem to use a juice that you do like), 1tbs whole whey, 1tbs mixed greens powder, 1tbs flax powder and 1tsp of nutritional yeast. With this drink you can take vitamin C, E, Zinc and selenium for antioxidants - which contributes to energy as well.
I have learned this info through research, as you can see I am still a student so in what I have told you you should certainly do more research to find what is right for you. Good luck!