An analysis of published research backs the notion that healthy adults who engage in strength training will build muscles better if they take protein supplements.
The review, published recently in the American Journal of Clinical Nutrition, looked at 22 studies published between 1995 and 2010, which included almost 700 subjects. Twelve of the 22 studies supplemented with a combination of whey, casein, and/or milk proteins; six studies supplemented with whey protein; two studies supplemented with essential amino acids; one used casein protein only and one used egg protein. Most studies used protein supplementation immediately before, during and/or after the exercise session.
The review concluded that despite some discrepancy in published literature, protein supplementation does increase muscle mass and strength when combined with prolonged resistance-type exercise training.
— Anne Aurand, The Bulletin