I wish I knew..great question! I do know that the yellow ones have more sugar in them than the red and green. I know that important from a diabetic standpoint. (I have diabetes), but, I did a little quick research online and found an ideal protein website that has a list of must-haves for easy meal planning...it does list all 3 pepper colors, so I guess it is a select...of course, it is my guess...others can chime in if they have different information..

Here is the site:
http://www.iamedicalspa.com/weight-l...cery-list.html