Phenylalanine is a forerunner of tyrosine, the anti-depressant dopamine, norepinephrine, epinephrine and the skin pigment, melanin. It is also a precursor of phenylethylamine, which is used as anti-depressant dietary supplement. It is naturally present in mammalian breast milk.
Eating foods rich in phenylalanine will help prevent mood swings, help you out of lethargy, sluggishness, feelings of low morale and anxiety.
beef, poultry, pork, fish, milk, yogurt, eggs, cheese, soy products, and certain nuts and seeds