Do higher protein diets harm our bones?

Calcium, that is what we think about when someone talks about bone health. What is often not well appreciated is the role of protein.

About 50% of our bone volume is protein. Calcium and other minerals are important, but protein structures provide the underlying matrix for bone mineralization.

In 2020 I fractured my ankle. I had surgery for my fractured fibula. I have treated hundreds of patients with fractures – but it was not until I broke a bone that I fully realized what healing from a broken bone involves.

One would like to think that when you break a bone – you just need to line up the parts and let them grow back together – simple right. I knew the basic physiology of bone healing from school but maybe underappreciated how big a deal it was.

Recovering from my ankle fracture I had a tremendous amount of swelling for a longer period of time than I would have guessed. It was a good reminder to me of just how much stuff is going on in the process of bone healing.  

Even when our bones are not needing to repair themselves from a fracture they are remodeling themselves. There is an ongoing process of tearing down and building up bone. As you can guess these processes involve lots of proteins on many different levels – proteins your body needs to make. I will include a link to a video below describing these processes.

Our bones not just give us structure but have other important functions such as being a storage depot for calcium. Our bodies need a very consistent amount of calcium in our blood stream for us to remain alive. These levels are controlled by proteins and protein like substances such as the parathyroid hormone that are constantly being made and broken down.

An often overlooked function of our skeletal system is the production of blood cells. Our red and white blood cells start their lives out arising from stem cells in our bone marrow. These are cells with lots of protein structures with a high demand of protein building blocks. Red blood cells are loaded with the protein (metalloprotein) hemoglobin. White blood cells have a dizzying array of cell surface proteins that serve many purposes including as receptors for other proteins and displaying pieces of viruses, bacteria and other pathogens to other cells.

Hopefully this article gives you a sense of the important role that protein has in our bone health. Getting adequate calcium intake is essential for bone health, however your bones also need the building blocks you get from the protein you eat.

With all the demand the bones have for protein building blocks it is odd that there is a commonly held belief that higher protein diets are bad for your bones. It appears this belief may stem from studies done decades ago (video).

The National Osteoporosis Foundation published an article in 2017 describing their analysis and review of studies looking at higher protein diets and bone health. In their conclusion they stated that “Current evidence shows no adverse effects of higher protein intakes (on bone health measures).” 

The German Nutrition Society published a review in 2023 looking at the question if protein intake above the current recommended amounts is beneficial for bone health. They discussed in the article many of the limitations of the scientific literature making it very difficult to come to firm conclusions. They pointed to studies with inconsistent results and that many studies were of poor quality. In the discussion section they stated that: “Osteoporotic fractures are the most important outcomes of impaired bone metabolism. Our results indicate that a beneficial effect of a protein intake above the recommendation (1.0 g/kg BW/day) in adults > 65 years of age on bone health, specifically hip fracture risk, cannot be excluded.

As with much in science and medicine it is difficult to make absolute statements based on only the available evidence. I do think however there is broad consensus that “adequate” protein intake is essential for bone health. The International Osteoporosis Foundation makes very firm statements regarding the need for adequate protein intake for all ages. Please check out their statements here for more detailed information.

I will provide a link below to a page on bones I have created that will be periodically updated. I will include links to the studies noted above as well as other items you might be curious about.

Do you ever wonder why our blood cells are manufactured inside of our bones?  I have.  Check out this video that discusses one theory of why.

For more information about the process of bone remodeling check out this 4 minute video that has cool animated illustrations. Notice all of the roles that proteins play in these processes.

Click here for more stuff All About Bones .

The next article will talk about muscle. If you are ready to read that article click here. Otherwise in about a week I will be posting the next article to Facebook and sending it out to my subscribers.

Thanks for listening,

Russ

If this is the first Health Matters article you have read, you can check out my 2 part introduction to the series here.

As an aside I broke my ankle on a trail at Indian Cave State Park. We were on a training hike. We were training for a multiple day trek through the mountainous backcountry of the Philmont Scout Camp. I had a 50 pound pack on my back, we were going up a steep muddy rutted trail when my foot slid into the rut and I basically sat on it. What I hollered out was not exactly appropriate.

While that injury was not a great memory I do have other fond memories of Indian Cave State Park. The trails there are some of the best trails I have hiked in Nebraska. Last year we returned to the trail where I broke my ankle. Check out this brief article from last year. Click here for more information or here for some more of my favorite hikes.