hydrogen, oxygen, and nitrogen are the four big elements that make up about 96% of our bodies. Calcium, potassium, sodium, magnesium, and phosphorus are the five essential elements, while iron, zinc, manganese, copper, molybdenum, iodine, chromium, and selenium are eight essential trace elements in the human body. The body cannot produce essential elements; thus it needs to acquire them from food sources to maintain good health and well-being.
Essential elements are called “minerals” or “dietary minerals.” Minerals exist in rocks and the soil of the Earth’s crust. So far, there are 5,300 known minerals. Nevertheless, it is the pure chemical elements, such as calcium or phosphorus, rather than minerals like limestone or apatite that are needed to maintain optimal health. This book presents a new concept, using the term essential elements to replace minerals.
Calcium is an essential element. The body contains about one kilogram of calcium, of which 99% is stored in the bones and teeth. The remainder is distributed in various organs and tissues. Calcium is involved in a multitude of important functions, such as the release of neural transmitters and muscle contraction. There is a homeostasis between calcium ions in the bones and calcium ions in the bloodstream. Excessive calcium in blood is actively deposited into the bones, and calcium is readily released from the bones when the blood level of calcium becomes too low. Prolonged calcium insufficiency can bring about osteoporosis.
What Are the Major Functions of Calcium?
• Bones and teeth. Bones are in a dynamic state and are constantly being repaired or rebuilt. All the calcium in your bones will be replaced within 8–12 years, but calcium in your teeth will never be replaced once deposited. The interplay between osteoblasts (bone-forming cells) and osteoclasts (bone-removing cells) in the bones is essential for maintaining bone health. Osteoblasts deposit calcium in the bones, and osteoclasts release calcium from the bones. During the growth phase in childhood, osteoblasts are actively adding calcium to the bones, while in patients with osteoporosis, osteoclasts are actively removing calcium from the bones.
• Blood coagulation. Blood coagulation factors require calcium as a cofactor. Binding to calcium enables these blood coagulation factors to adhere to platelets. Without binding to calcium, these blood coagulation factors cannot form blood clots, causing uncontrollable bleeding.
• Neurotransmitters. As the action potential (transporting electrical signals from one cell to the next) arrives, calcium ions stored in the neurons are released, which triggers the release of neurotransmitters, such as dopamine, to the neighboring neurons.
• Muscle contraction. Muscle cells form muscle fibers, which are comprised of actin and myosin. Actin and myosin display a mutual attraction to each other. The binding of actin to myosin induces muscle contraction. In a resting state, troponin and tropomyosin sandwich themselves between actin and myosin to prevent actin from binding to myosin. When the brain sends a message for muscle contraction, calcium ions are quickly released and bind to troponin. Calcium binding to troponin causes the movement that removes troponin and tropomyosin from between actin and myosin, hastening the binding of actin to myosin and the subsequent muscle contraction.
What Are the Symptoms of Calcium Deficiency?
• The major symptoms of calcium deficiency include fragile bones, impaired vision, atrial fibrillation, and osteoporosis.
What Are the Causes of Calcium Deficiency?
• Diet. An unhealthy diet is the main cause of calcium deficiency. According to data from the USDA, 78% of women and 87% of teenage girls are calcium insufficient. Only 55% of men obtain sufficient calcium from foods. Hence it is not surprising that osteoporosis is now a serious health issue in the US.
• Parathyroid hormone. Parathyroid hormones regulate calcium concentrations in the blood. Low blood calcium triggers the secretion of parathyroid hormones from the parathyroid gland. Parathyroid hormones then release calcium from the bones and elevate blood calcium levels. When blood calcium is too high, the body will attenuate the secretion of parathyroid hormones. Parathyroid hormone disorder can contribute to problems related to calcium deficiency.
Prevention and Treatment of Diseases
• Prevention. Meta-analysis confirms that calcium can help prevent bone fractures (46), preeclampsia (97), and colorectal cancer (56).
• Treatment. Calcium supplements help treat hypertension (78).
Which Food Items Are Calcium Rich?
Milk and other dairy products are excellent sources of calcium. Plant-based foods like broccoli, spinach, tofu, and nuts, as well as animal-based foods like eggs, sardines, and salmon, contain high amounts of calcium.
This list of calcium-rich food items is adapted from information provided by the NIH Office of Dietary Supplements.
| FOOD | PORTION | CALCIUM CONTENT, MG | % DAILY REFERENCE VALUE |
|---|---|---|---|
| Yogurt | 8 ounces | 415 | 42 |
| Sardine | 3 ounces | 325 | 33 |
| Cheese | 1½ ounces | 307 | 31 |
| Milk | 8 ounces | 276 | 28 |
| Tofu (hard) | ½ cup | 253 | 25 |
| Salmon | 3 ounces | 181 | 18 |
| Tofu (soft) | ½ cup | 138 | 14 |
| Cabbage | ½ cup | 79 | 8 |
| Orange | 1 | 60 | 6 |
| Kale | ½ cup | 47 | 5 |
Daily reference value of calcium is 1,000 mg according to the 2013 FDA food-labeling guidelines.
What Are the Recommended
