High protein diets do not adversely affect bone density [Study]

We are often told, and believe, that eating too much meat protein causes blood to become acidic, meaning calcium is leached from the bones in order to return the blood to a more alkaline state. Is this true, or can you eat plenty of meat without worrying?

If we look at the science, we will see there is no need to worry… but we do need to worry if eating too little protein! In short, you can enjoy your meat.

This study, for example, looked to determine the effects of a high-protein and high-potential renal acid load (PRAL) diet on calcium (Ca) absorption and retention and markers of bone metabolism. Levels of vitamn D can affect calcium status so all participants (postmenopausal women) were given vitamin D supplements, thus taking that variable out of the experiment.

They found a diet high in both protein and PRAL:

• Increased calcium absorption; this at least partially compensating for an increase of calcium in urinary excretion
• Resulted in no change in either bone resorption or formation biomarkers; this indicates a high-protein diet is not detrimental
• There was an increase in serum IGF-I and a decrease in serum PTH; this in fact suggests that a high-protein diet could be beneficial to bone health

They concluded their results ‘indicate a high-protein diet has no adverse effects on bone health.’

Click for abstract and full paper.

Related studies

Too much protein may lead to bone thinning, medium levels* has no discernable effect, and too little has much larger consequences on bone health, leading t0 more fractures.  Some investigators have concluded that dietary protein is a more important regulator of urinary calcium than dietary calcium intake.  Full paper.

*Studies show medium levels of protein intake (roughly 100–150% of the RDA or 1.0–1.5 g protein/kg), measures of calcium and skeletal metabolism are normal (1, 2, 3, 4, 5).

‘Under controlled conditions, a high meat compared with a low meat diet for 8 wk did not affect calcium retention or biomarkers of bone metabolism in healthy postmenopausal women. Calcium retention is not reduced when subjects consume a high protein diet from common dietary sources such as meat.’  Abstract and full paper.