Thursday, October 24, 2013

What else should I take besides calcium for my bones (Part V of "Should I take calcium")

Calcium is necessary to build and maintain strong bones, but it is not necessarily sufficient.  To focus in on calcium supplements as a top priority solution to the prevention and treatment of osteoporosis is to lose sight of the complexity of bone-building and maintenance, and to risk the unwanted consequences of too much of a single good thing.

Vitamin K, as mentioned in Part IV of this series, is essential to the modification of proteins integral to blood-clotting and the proper use of calcium.  Vitamin K1, available from plants particularly of the leafy green variety such as kale, is the K form involved with normal blood coagulation.  People are rarely deficient in K1 insofar as clotting is concerned. At times, individuals who have experienced problems such as deep vein thrombosis (clot) in leg veins or pulmonary emboli (blood clots traveling to the lungs) are put on warfarin (aka Coumadin) which partially blocks the function of K1 thus preventing future unwanted clot formation.  Unfortunately, people on long-term warfarin are known to be at greater risk for arterial calcification.

K1 can be converted to K2 by intestinal bacteria.  While there is dispute as to whether or not bacterial K2 is available for absorption into the body through the gut wall, it is known that women with high intake of K1 are less likely to sustain hip fractures, and lettuce intake--a good source of K1--was inversely proportional to future incidence of hip fractures in the Nurses Health Study(1).  Those medical professionals eating lettuce once or more daily had a nearly 50% hip fracture risk reduction compared to those downing one or less salads per week. 

It is difficult to take in enough K1, however, to meet your K2 requirements.  Researchers from The Netherlands compared the efficacy of K1 to K2 in the MK-7 form with respect to the production of proteins essential to proper bone calcification and found the K2 more effective and far more long-acting in its bone-forming functions(2).

Therefore, in order to build strong bones AND keep unwanted calcium out of your blood vessels, daily intake of K2--especially the MK-7 molecule--is absolutely the answer.  Besides the Rotterdam study cited in my previous post, multiple other clinical studies correlate K2 intake with long term vascular health. 

While calcium is good and necessary, vitamin K2 is essential.  Vitamin D, of course, is also crucial as are multiple other micro-nutrients.  In the sixth and final installment of this series, I'll give you my best advice as to "Should you take calcium" and what you should be taking as well for optimal bone and vascular health.
1) Feskanich D et al.  Vitamin K and Hip Fractures in Women, a Prospective Study.  Am J Clin Nutr vol. 69 no. 1 74-79. 
2) Schurgers LJ et al. Vitamin K–Containing Dietary Supplements: Comparison of Synthetic Vitamin K1 and Natto-derived Menaquinone-7. Blood vol. 109 no. 8 3279-3283.                                    

Wednesday, October 09, 2013

The Calcification Paradox (or Part IV of Should I Take Calcium?)

As I mentioned in Part III of this series, there is an inverse association between decreased bone calcification and increased vascular calcification, neither of which is a good thing.  In other words, those who shrink and crumble into the osteopenia/osteoporosis thing are also those most likely to deposit unwanted calcium in their aging blood vessels.  The heart of this supplemental calcium controversy (do I take it or not?) lands squarely here: how does our body calcify that which holds us upright while also preventing calcium build-up where it does not belong? What matters here is not just the necessity of incoming calcium to balance calcium loss but also an ongoing incoming supply of the known co-factors needed for proper calcium use.

Back, once again, to an evolutionary perspective.  In Part II I mentioned our Ice Age ancestors who ate a high-calcium diet of plants and insects and little or no grain--a food source both low in calcium and high in phytates (substances that bind calcium thus preventing effective absorption).  Now let's go back even further to our remote water-based relatives who spent their lives swimming about in calcium-rich seas.  Early evolutionary pressure, therefore, required the development of mechanisms to prevent widespread calcification through their soft, fishy tissues. The ability to survive and thrive depended--still depends!--on the limitation of calcium deposition solely to skeletons be they external shells or, much later, internal bones. Elaborate regulatory mechanisms developed over eons that promote calcium phosphate crystallization in the right place and prevent it elsewhere.

The central actors in strong bone production are cells that package mineral matrix--a mixture of calcium, phosphate, enzymes, and proteins--and then deposit it along collagen fibers also produced by these cells.  This can happen in the right place (in bones that are growing as in children or repairing as in adults) or the wrong place as in aging aortas or arteries.  Cells that can turn into osteoblasts (bonemakers) are not only found within the skeleton but also in the walls of blood vessels.  The most important protein responsible for bone mineralization is osteocalcin which is dependent on vitamin K2 for proper function.  The most important protein responsible for the prevention of mineralization outside of bones is matrix gamma-carboxy glutamic acid which is also dependent on vitamin K2 for proper function.  Do you see where this is going?

I am here to tell you that I had no idea why I've been taking vitamin K2 regularly for the past year except for a vague notion that it was good for bone health.  I'm certain that I learned nothing about this in medical school decades ago when the importance of vitamin K to proper blood clotting was emphasized but no one mentioned its importance to mineralization. For those of you who haven't spent hours studying the literature on vitamin K as I have while writing this series, there are two main forms of K: K1 important to normal blood clotting function, and K2 which is integral to the deposition of calcium in the body.  More on that in Part V.

Recent studies abound on the benefits of K2 with respect to cardiovascular health.  The Rotterdam Study, published in 2004, found that persons with the highest levels of K2 were less than half as likely to die of coronary heart disease or develop severe aortic calcification over a seven year period than those with the lowest levels, and almost 75% less likely to die of anything in that same time period. 

Wow, if you haven't got K2, get some!
1) Geleijnse, J et al.  Dietary Intake of Menaquinone Is Associated with a Reduced Risk of Coronary Heart Disease: The Rotterdam Study. J. Nutr. vol. 134 no. 11 3100-3105.