Can too much protein be harmful?
The short answer is yes. If you eat too much protein, there may be a price to pay. For example, people that eat very high protein diets have a higher risk of kidney stones. Also a high protein diet that contains lots of red meat and higher amounts of saturated fat might lead to a higher risk of heart disease and colon cancer, while another high protein diet rich in plant-based proteins may not carry similar risks. However, for the average person (who is not an elite athlete or heavily involved in body building) it’s probably best to aim for no more than 2 gm/kg; that would be about 125 grams/day for a 140-pound person. New information could change our thinking about the maximum safe amount, but until we know more about the safety, risks and benefits of high protein diets, this seems like a reasonable recommendation.