Researchers from a 2013 scientific review published in the British Journal of Nutrition explain how the claim that too much protein can be detrimental to bone health came to be. They outline how it was born from the long-standing acid load hypothesis and its relation to osteoporosis, a bone disease that affects roughly 10 million Americans (per the Bone Health and Osteoporosis Foundation). Research findings from the 1960s involving patients with chronic kidney diseases claimed that foods, specifically animal protein, could cause an overproduction of acid in the body, leading to bone deterioration.
However, more current studies have found the opposite connection. Rather, eating greater amounts of protein on a daily basis that exceed the standard dietary guidelines has been linked with increased bone mineral density (BMD), slower progression of bone loss, and a reduced susceptibility to hip fractures (via Current Opinion in Clinical Nutrition and Metabolic Care). Presently, the recommended daily intake for protein stands at 0.8 grams per kilogram of body weight.