High dietary protein intake and protein-related acid load on bone health

Authors: Cao, Jay

Submitted to: Osteoporosis Report
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/22/2017
Publication Date: N/A
Citation: N/A

Interpretive Summary: Protein is an important nutrient for humans and the current Recommended Dietary Allowance (RDA) is 0.8 g protein per kg body weight per day. There is a concern over high dietary protein intake ( i.e. above the RDA) on bone health because protein is a source of acid load when it is metabolized and is often associated with increased urinary calcium excretion. The purpose of this article is to review the most recent epidemiological and interventional clinical research regarding how dietary protein affects calcium metabolism and bone health. Recent research findings indicate that a high protein intake has beneficial effects by increasing intestinal calcium absorption, increasing blood IGF-1, and lowering blood parathyroid hormone. These above beneficial effects compensate for the negative effects of protein-induced acid load on urinary calcium excretion. Future research should focus on how other dietary and physiological factors reduce the acid load and maximize the positive effects of protein on bone.

Technical Abstract: Protein is an essential nutrient for humans and is required for maintaining optimal bone structure and growth. Consumption of high protein diets in excess of the Recommended Dietary Allowance of (0.8 g protein/kg body weight/d) is increasingly popular due to the benefits of protein on preserving lean mass and controlling appetite and satiety. Concerns exist over the impact of high protein intake on skeletal system because protein, as a major source of dietary acid load, is generally associated with increased urinary calcium excretion. However, many epidemiological studies show that long-term, high protein intake is positively associated with bone mineral density and reduced risk of bone fracture incidence. Short-term interventional studies demonstrate that high protein diet does not negatively affect calcium homeostasis. Existing evidence supports that the negative effects of the acid load of protein on urinary calcium excretion are offset by the beneficial skeletal effects of high protein intake through increasing intestinal calcium absorption, increasing circulating IGF-I, and lowering serum parathyroid hormone. Future research should focus on the role and the degree of contribution of other dietary and physiological factors, such as intake of fruits and vegetables, in reducing the acid load and further enhancing the anabolic effects of protein on the musculoskeletal system.