Research has shown that the amino acid phenylalanine improves the mood of depressed patients. Read more at: http://www.life-enhancement.com/article_template.asp?id=1987
Spirulina is shown to ameliorate anaemia and immunosenescence in older immune systems. The research paper can be found at: http://www.nature.com/cmi/journal/v8/n3/full/cmi201076a.html