DL-Phenylalanine is not something new for depression. I remember reading about it and taking it about 9 years ago. At the time it was suggested that it could help some people who did not respond to conventional(serotonin related) antidepressants. In my case, it would make me anxious and I promptly discontinued taking it.
L-Phenylalanine is an essential amino acid, however isolated pill form is absorbed/used differently than if you were to get it from food. Phenylalanine is a precursor to other amino acids and neurotransmitters thereafter.
D-Phenylalanine is a stereo isomer(same atomic components, different orientation) and as far as I know it does not naturally occur in the body.
From personal experience 5-HTP is an excellent amino acid for depression. It is a naturally occurring precursor to serotonin, and is synthesized in the body from an essential amino acid Tryptophan. Some people used Tryptophan for the same purpose, however it has to be taken in much larger doses.
It should be taken on an empty stomach at least 3 hours after eating with plenty of water. Some suggest taking extra B-6 vitamin while on 5-HTP. I personally used to take 25mg to 50mg a day
It has been suggested that large doses of 5-HTP could cause heart problems because some of it might be converted to serotonin in the bloodstream before it reaches the brain. As far as I know however there is no conclusive research to prove the above.
Tryptophan has been used in the 80s for depression, anxiety and sleep, banned by the FDA in 1989 until a few years ago because of a bad batch from a Japanese manufacturer that made 1500 sick including 30 or 40 deaths. Some people claim that outright banning of all tryptophan was a conspiracy between FDA and Pharmaceuticals (Prozac and other antidepressant use exploded soon thereafter).
Depression/Anxiety can occasionally be caused by numerous vitamin and mineral deficiencies. Some examples of deficiencies are magnesium or vitamin B-3.
For general stress I recommend B vitamin complex and vitamin C broken up into small doses 2 to 3 times a day, and a multivitamin every other day or so.
Do not take large and/or continuous doses of any single vitamin, mineral, or amino acid. Doing so usually results in creating imbalances in your body. You will deplete other vitamins/minerals.
I am generally not a fan of pharmaceuticals, if you take them and they work for you thats great. I however found very unpleasant side effects with their use. Someone here mentioned citralopram(Celexa in my case) because of its mild side effects. In my personal experience they are terrible. Everything was great while I was taking it, I even quit smoking without feeling too bad. The problems started when I stopped taking it. Terrible headache for 3 weeks, and I felt like I was drunk for those 3 weeks and also started smoking again. Thereafter every time I tried to stop smoking the citralopram withdraws side effects would return, this lasted for about 3 years. I also have taken Zoloft and Wellbutrin/Zyban again unpleasant side effects, however not as bad as Celexa and only present while taking them.
Finally, looking into Cognitive Therapy or Rational Emotive Therapy could also help, but in my opinion only after the physical aspect has been somewhat resolved. The idea behind those two therapies is that you create your automatic/semi-conscious thoughts, those thoughts trigger your emotions. The difficult part after years of depression, anxiety, phobias, addiction or just beveling something, is separating facts from you imagination/interpretation both of which are fused can feel very real. If you have not realized this yet, the ideas from those therapies are being used for improving trading performance - don't worry its not a quick or easy process.
Good Luck and suplement with caution.