The Myth About Calcium and Bone Loss

A recent article by Dr. Susan E. Brown, PhD on the Women to Women.com website clarifies the role calcium plays in bone loss and osteoporosis:

Bone loss is not caused by low calcium intake, and calcium by itself will prevent neither bone loss nor needless osteoporotic fractures.

Bone health depends not so much on calcium intake, but rather on its metabolism and utilization. The major players in this regard are vitamin D, vitamin K, and magnesium — which are woefully under-publicized in the campaign against osteoporosis.

Calcium’s role in bone health:

Calcium is the most abundant mineral in the human body and has several important functions. Two percent of our total body weight is made of calcium, and more than 99% of total body calcium is stored in the bones and teeth, where it supports their structure. The body gets the calcium it needs from the intake of calcium-rich foods including dairy products, which have a high concentration per serving of highly absorbable calcium, and also many other foods, such as dark, leafy greens, nuts, beans, and seeds, which have varying amounts of highly absorbable calcium.

When blood levels of calcium drop too low and dietary calcium intake is insufficient, the body will obtain calcium by extracting it from the bones. Ideally, calcium that is taken from the bones will be replaced when calcium levels are replenished. But to replace the calcium in your bones, an intricate process involving intake, metabolism, and utilization must take place.

While calcium is clearly important, there are at least 19 other key nutrients that each play a vital role in the structural integrity and overall health of our bones. To put the larger picture in context, it is sometimes useful to think of bone as a brick wall where the bricks are made of calcium and the other key nutrients make up the mortar. Without mortar, the wall is unstable. Bricks may fall out, making the wall even weaker. Just like a brick wall without mortar, without vitamin D, vitamin K, and magnesium, bone will lose its calcium.

Calcium and vitamins D, K, and magnesium:

Vitamin D plays a key role in the prevention of many chronic diseases, including cancer, heart disease, diabetes, autoimmune disease, and osteoporosis. When it comes to bone, we now know that vitamin D is the key to calcium absorption. Without vitamin D your body can only absorb 10–15% of dietary calcium — so even if calcium is present, the body can’t use it! When vitamin D is added, the absorption of dietary calcium increases to 30–40%. So, both calcium and vitamin D are necessary to prevent osteoporosis — including postmenopausal osteoporosis.

Most Americans don’t get enough vitamin D — especially during the winter months, when there is less sunlight. Certain people may also be at a high risk for vitamin D deficiency, including the elderly, the obese, dark-skinned individuals, teenage girls, those who spend little time outdoors, and those who regularly use sunscreens. Because it is a fat-soluble vitamin, vitamin D deficiencies also occur in people with fat malabsorption syndromes such as in celiac disease, cystic fibrosis, and inflammatory bowel disease.

We have recently learned that Vitamin K is critical for calcium utilization and regulation. Vitamin K helps proteins bind to calcium and transports them to where they are needed in bones, organs, and other tissues. Vitamin K is also needed in the bone to produce a protein called osteocalcin, which, as the name suggests, helps bind calcium to the bone.

Magnesium is needed for calcium absorption and bone formation. Magnesium is an essential cofactor in 80% of all cellular enzymes — including the thyroid hormone calcitonin, which regulates bone turnover. Magnesium is also needed by the liver enzymes that convert vitamin D into its active form, known as calcitriol.

It matters what kind of calcium you get:

Calcium comes in many different forms. Even with the other nutrients needed for its absorption, some forms are not as readily absorbed as others.

• Calcium citrate is a highly absorbable calcium compound. This form does not require the hydrochloric acid (HCl) in the stomach to be absorbed. Thus, calcium citrate is very readily absorbed or bioavailable, and a good choice for people with low stomach acid.
   
• Calcium ascorbate and calcium carbonate are generally not as easily absorbed as the citrate forms if HCl is low. However, they are absorbed quite readily when taken with food.
   
• Generally speaking, all types of calcium are absorbed more easily if taken with meals — no matter what form you choose.

Calcium supplements should always be balanced with magnesium. I recommend supplementing with at least half as much magnesium as calcium (a ratio of one part magnesium to two parts calcium), but my preference as a clinician is for nearly as much magnesium as calcium. People with inflammatory changes such as osteoarthritis, in particular, want to use equal amounts of magnesium and calcium (1:1). Some bone specialists even favor magnesium-centered formulations with equal or slightly more magnesium than calcium.

Good dairy-free sources of dietary calcium:

• Whole wheat products
• Vegetables in the brassica family: broccoli, kale, cabbage
• Dark leafy greens: collards, spinach, turnip greens, dandelion greens, mustard greens, beet greens
• Rhubarb
• Canned fish/crustaceans with bones, e.g., sardines, pink salmon, and shrimp
• Beans/legumes, edamame, tofu, tempeh, black-eyed peas, and black beans
• Okra
• Nuts and seeds, almonds, sesame seeds
• Mineral water
• Herbal teas and infusions, e.g., oatstraw, nettle, red clover