INDIANAPOLIS - Protein shakes and supplements have bulked up in popularity lately, especially among young adults, but some doctors think these supplements might be doing more harm than good.

Dr. Islam Ghoneim, a kidney and pancreas transplant surgeon at St. Vincent Health, said processed proteins -- like those in shakes, powders and pills -- can lead to kidney disease.

"A normal individual's kidneys can handle protein shakes if they're used for very short durations, and that's usually a matter of weeks," Ghoneim said. "It may be successful in the short term, but should not be used for extensive periods of time especially not without consulting a health care provider or physician."

Ghoneim said protein supplements are fine for healthy people who use them in addition to eating a healthy diet, but some people use protein supplements exclusively.

At Good Earth in Broad Ripple, they too stress the importance of natural proteins and not over-doing the popular shakes and bars.

"Great sources that you're going to find in most health food stores are going to be nuts and beans. There are some soy products and tofu for vegetarians and vegans, so there's a lot of really good sources," said Rudy Nehrling, manager at Good Earth. "Eating as close to the earth, plant-based proteins is going to be your best bet. That's where you're not going to over-do it in that sense."

Ghoneim says those who already have kidney or liver problems shouldn't use protein supplements at all.