The Role of Calcium in Their Everyday Function
Calcium is required for skeletal and cardiac muscle contraction, blood-vessel expansion and contraction, secretion of hormones and enzymes, and transmission of impulses through the nervous system. The body strives to maintain constant concentrations of calcium in blood, muscle, tissues, and intercellular fluids, though less than 1 percent of total body calcium is needed to support these functions. The rest of your calcium – 99 percent – is stored in your bones and teeth, where it supports their structure. And bone itself undergoes continuous remodeling, with constant resorption (breakdown of old bone) and deposition of calcium into a newly formed bone collagen matrix. The balance between bone resorption and deposition changes with age. Bone formation exceeds resorption in growing children, whereas in early and middle adulthood the two processes are relatively equal. In aging adults, particularly among postmenopausal women and men over sixty years old, bone breakdown exceeds formation, resulting in bone loss that increases the risk of osteoporosis over time.
We all need calcium to survive, just as we need water. But there is a certain balance to be struck, a so-called homeostasis. In fact, you can think of the homeostasis of calcium ions in the body as a center of gravity for a number of physiological processes. If there is too little calcium in your blood (a condition called hypocalcemia), soft-tissue cells – especially nerves and muscle, which rely on calcium to operate – become dysfunctional. Your entire neuromuscular system will become abnormally excitable, and impulses may be triggered spontaneously. This, in fact, sends your body into convulsions as muscles, including those of the respiratory system, contract uncontrollably. In this situation, a person can die from failure to breathe. The heart, which also depends on calcium to beat properly, can lose its rhythm, with fatal consequences. Conversely, if there is too much calcium in the blood (a condition called hypercalcemia), organs calcify and eventually cease to work. This is especially true for the kidneys. Blood vessels will calcify, rendering them less plant and thus increasing the risk of stroke and myocardial infarction. Those excess calcium ions have an opposite effect on the nervous system, abnormally depressing it and causing depression, constipation, and confusion. Having too much calcium can be just as hazardous as having too little.
So you can see how important it is to maintain steady and healthy levels of calcium in the body. You can also see how vitamin D promotes healthy bones by indirectly maintaining adequate serum calcium and phosphorus for bone mineralization to occur. Vitamin D controls the level of calcium in the blood. If there is not enough calcium in the diet, then it will be drawn from the bone. High levels of vitamin D (from the diet or from sunlight) will actually demineralize bone if sufficient calcium is not present.
We know that if you are vitamin D deficient, as most Americans are, your body will steal the calcium out of your bones. That is what would cause you to have osteopenia or osteoporosis, severe low bone density with increased risk of fracture. But being vitamin D deficient also prevents calcium from coming into the bones. And as a result, there’s nothing more than a Jell-O-like collagen matrix left behind, and it will get hydrated just like Jell-O and water.
Women who complain of throbbing, aching bone pain are sometimes met with doctors who can’t understand it. When the doctor presses on a patient’s bones almost anywhere, she will often wince in pain, and that’s because the doctor is pressing down where there’s no mineralized bone on the surface. It’s simply a Jell-O-like substance, triggering significant discomfort. The covering on the bone is full of nerve endings, and if there is no mineralized bone underneath it but instead a rubbery “Jell-O”, then when the doctor presses on it, that compresses the covering and excites those nerve endings, resulting in pain. Like Jell-O, the collagen matrix expands under the periosteal bone covering, causing throbbing, aching bone pain. When people are sitting with aches in their hips or lying in bed with throbbing aches in their bones, it can be very hard for physicians to immediately think of vitamin D deficiency. But often that’s exactly what’s causing the problem.
Making sense of this remarkable relationship between calcium regulation and vitamin D has opened many new doors in science and medicine. In addition to shifting the course of treatment for people suffering from bone disease, it has paved a new path for people suffering from calcium-regulation disorders due to underlying medical conditions. It suddenly became possible, for example, to treat patients who had lost their parathyroid glands or their kidneys and, as a result, could no longer regulate the level of calcium in their blood. Now that we had the ability to synthesize activated vitamin D hormone commercially, we could treat these patients with activated vitamin D and calcium. The effects were dramatic, putting an end to their painful muscle spasms, convulsions, and chronic bone disease.