Here's [1] and interesting link summarizing the research about nutritional supplements that can help people with bipolar disorder. Since many symptoms are similar between BPD and bipolar(and i don't think the is such research  for BPD), it might be a good resource to talk over with your therapist/psych. 

BTW ,for me ,magnesium and omega-3 do help greatly with bpd. 

Feel well :) 

[1]http://evolutionarypsychiatry.blogspot.se/2012/12/alternative-therapies-and-bipolar.html