Protein and Bone Health: Does More Protein Help or Harm Bones?

How to read the evidence on this page

Labels used: "moderate", "low" or "insufficient" certainty as stated by the review authors; "mixed" where studies disagree; "preclinical" for lab or animal work; and "Proper evidence not found". BMD is a scan measure, not the same as a broken bone. Trials in people who already eat enough protein do not tell us about people who eat too little, and the reverse.

What reviews found

1. Does higher protein raise lumbar spine BMD?

   Unclear

   Moderate evidence of a protective effect on lumbar spine BMD, but no effect on total hip, femoral neck or total body BMD or bone biomarkers [1]

   Moderate for lumbar spine only (NOF review, 2017)

2. Does protein change fracture risk?

   Unclear

   A 2009 review found a small benefit on BMD that may not translate into reduced fracture risk in the long term [2]

   Limited, older review

3. Is there evidence for fractures in recent reviews?

   Unclear

   A 2023 umbrella review (11 systematic reviews) found it unclear whether intake above current recommendations or animal versus plant protein affects bone, with possible evidence of reduced hip fracture risk with high versus low protein [3]

   Mostly low or insufficient certainty

4. Does protein with calcium and vitamin D help more?

   Unclear

   Limited evidence did not support an effect on lumbar spine BMD, hip BMD or forearm fractures [1]

   Limited

The "acid load" worry

A common claim is that protein makes the body acidic and pulls calcium from bone. A 2011 systematic review of 55 studies on dietary acid load and bone found that calcium balance studies did not show loss of whole-body calcium with higher net acid excretion, and concluded a causal link between dietary acid load and osteoporotic bone disease is not supported by evidence. [4] A 2017 review noted that short-term interventional studies show a high-protein diet does not negatively affect calcium homeostasis. [5] The same review argued long-term high protein intake is associated with higher BMD and lower fracture incidence in epidemiological studies, which cannot prove cause. [5]

Protein is one piece

NIAMS lists low-calcium and low-vitamin D diets, and excessive dieting or poor protein intake, among things that may raise the risk of bone loss and osteoporosis. [6] NIAMS advises eating foods that include calcium, vitamin D and protein, and a diet rich in all nutrients. [7] For calcium, the UK NHS says adults need 700 mg a day, which most can get from their diet. [8] See Calcium, Vitamin D and Osteoporosis and Bone Health.

Postmenopausal women and older adults

A 2014 consensus statement from ESCEO, a European osteoporosis society, recommends protein of 1.0 to 1.2 g per kg of body weight per day for postmenopausal women, with at least 20 to 25 g of high-quality protein at each main meal. [9] That is a society recommendation for that group, not a personal target; see Protein for Women: Menopause, Bone and Muscle and Protein for Older Adults. Muscle and falls also matter: Sarcopenia and Muscle Loss.

Kidney disease changes the question

People with chronic kidney disease may have different protein limits and bone problems; see Protein and Kidney Disease.

Related

Protein Foundations · High-Protein Diets: Benefits and Risks