Conjugated linoleic acid, or CLA, is derived from animal sources. Chickens fed their natural diet and raised organically produce eggs with higher levels of CLA. CLA has been found to have antitumor activity at levels achievable through your diet. In other animal studies, CLA has been shown to help with regulation of glucose and to decrease the percentage of bodyfat. CLA is found in the yolk of the egg.
So stop throwing away that Yolk! It's good for you!
above information and picture comes from http://www.muscleandfitness.com/nutrition/gain-mass/4-more-reasons-load-eggs/slide/3