Osteoporosis and Bone Strength, A Secret Ingredient
The familiar tune when it comes to bone strength and osteoporosis has been "get enough calcium," and that hasn't changed. However, there may be a new stanza to the song, and the subject is a secret ingredient called osteocalcin.
What is osteocalcin?
Investigators at Rensselaer Polytechnic Institute are believed to be the first to show how the protein osteocalcin is significantly involved in bone strength and thus has a major role in the development of osteoporosis. While these researchers did not discover osteocalcin, they did uncover critical information about how it works, which could lead to better ways to prevent bone fractures and osteoporosis.
Osteocalcin is found in both bones and teeth and is secreted by cells called osteoblasts, whose other function is to help build bone. The secreted osteocalcin is deposited inside the matrix of bone, where it contributes to bone strength.
The bone study
Researchers at Rensselaer, along with those from Villanova University, the Hospital for Special Surgery in New York, and Yale University, explored bone structure at the nanoscale level and discovered that osteocalcin and another protein, osteopontin, join forces to form dilatational bands, which help protect the bone from breaks and other damage. If the impact is too great, however, bones can break.
This study is important because the investigators, led by Deepak Vashishth, head of the Department of Biomedical Engineering at Rensselaer, are the first to discover evidence at the nanoscale level of how bones can fracture. According to Vashishth, their work "implicates, for the first time, the role of osteocalcin in giving bone the ability to resist fracture."
Armed with this new knowledge about the structure and mechanics of osteocalcin, scientists may now study to see if strengthening osteocalcin can result to an improvement in bone strength and thus help prevent osteoporosis, noted Vashishth. One way to accomplish this may involve spinach and other green leafy vegetables or, more precisely, vitamin K.
That's because osteocalcin cannot be absorbed into bone unless it is in a certain form (carboxylated), and vitamin K acts on osteocalcin to get it into this form. Vitamin K is necessary for the activity of the enzyme carboxylase, which allows carboxylation of osteocalcin proteins.
So while calcium (and vitamin D) are still critical for bone health, Vashishth pointed out that "We believe there's more to the story than just calcium, and the results of this new study raise an important question about vitamin K." For better bone strength and to help prevent osteoporosis, getting plenty of the secret ingredient, vitamin K, in the form of leafy greens such as spinach, arugula, and kale could be the ticket.
Poundarik AA et al. Dilatational band formation in bone. Proceedings of the National Academy of Sciences 2012; early edition. doi:10.1073/pnas.1201613109