Is protein from animal sources or from plant sources more beneficial? 

'It does appear that protein from animal sources is an important source of protein for humans from infancy until mature adulthood. However, the potential health concerns associated with a diet of protein consumed primarily from animal sources should be acknowledged. With a proper combination of sources, vegetable proteins may provide similar benefits as protein from animal sources.'

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3905294/


'A plant-based diet, which emphasizes fruits, vegetables, grains, beans, legumes and nuts, is rich in fiber, vitamins and other nutrients. And people who eat only plant-based foods — aka vegetarians — generally eat fewer calories and less fat, weigh less, and have a lower risk of heart disease than nonvegetarians do.'

'In fact, the Dietary Guidelines for Americans recommends choosing a variety of protein foods, including eggs, low-fat milk and products made from it, beans and peas, soy products, and unsalted nuts and seeds. The guidelines also suggest replacing protein foods that are higher in solid fats with choices that are lower in solid fats and calories. The fats in meat, poultry, eggs and high-fat dairy products such as cheese are considered solid fats, while the fats in seafood, nuts and seeds are considered oils.'

http://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/meatless-meals/art-20048193?pg=1