@Derleth - thx for asking. Here is one source, the Harvard School of Public Health:

(intro)...Surprisingly little is known about protein and health...

(from the section: Protein Package)

Animal protein and vegetable protein probably have the same effects on health. It's the protein package that's likely to make a difference.

A 6-ounce broiled porterhouse steak is a great source of complete protein—38 grams worth. But it also delivers 44 grams of fat, 16 of them saturated. (2) That's almost three-fourths of the recommended daily intake for saturated fat. The same amount of salmon gives you 34 grams of protein and 18 grams of fat, 4 of them saturated. (2) A cup of cooked lentils has 18 grams of protein, but under 1 gram of fat. (2)

The bottom line is that it's important to pay attention to what comes along with the protein in your food choices.

sorry here is a ref link for that:

http://www.hsph.harvard.edu/nutritionsource/what-should-you-...

and one for the Mayo Clinic (which actually shows that meat isn't as bad for your heart as once thought, only 10-20% increases ur chances of heart disease, and 10-20% increases chances of diabetes) (as compared to vegetable protein which increases neither and prob decreases them):

http://www.mayoclinic.com/health/red-meat/MY01329