Calcium constitutes about two percent of the human body. It gives strength and structure to bones and teeth. It also plays a role in muscle contraction, transmission of nerve impulses, blood coagulation, activation of enzyme reactions, and stimulating hormone secretions. Recent research suggests calcium may also play a role in weight reduction.
A Necessity for Good Health
By Pamela Cannoy Kelle, R.D., C.D.E.
Approximately ninety-nine percent of calcium is present in the bones and teeth to provide the rigid framework of the human body. The remaining one percent of body calcium is extensively distributed in soft tissue and in extra cellular fluid. This seemingly tiny one percent plays a vital role in the precision with which plasma calcium is regulated by the parathyroid hormone, calcitonin.
Calcium nutrition depends on the total amount of calcium consumed, its bioavailability and the body’s vitamin D status. To ensure that adequate levels of calcium are absorbed, one must consume a sufficient amount of calcium. Over consumption is unlikely, as a woman would need to consume three to five times the usual dose in supplements a day to override the natural mechanism for protecting against overdose.
Most of the calcium eaten is unabsorbed and excreted in the feces. About half of what is absorbed is spilled into the urine given a person’s body size and the acid/base regulation of the body. It is important to note that those who consume high protein diets and those who consume processed high sodium diets have increased calcium excretion and loss.
Body Fat Disturbance
If calcium intake is low, vitamin D acts to increase intracellular calcium. Studies done by Michael Zemel, et al at the University of Tennessee, Knoxville postulate that increases in intracellular calcium aid production of fat storage. Therefore, calcium intake may be predictive of body fat weight. There are more studies currently unfolding as clinical trials continue.
If calcium intake is low or inadequate and vitamin D intake is low, the risk of osteoporosis increases with age. Once present, weakened bones become porous (like a sponge) and easily fracture or break. Sometimes a simple step off a curb can end with a major hip fracture. The opportunity to increase bone strength and bone mass is greatest from childhood into adulthood (age 30). After this age, calcium is still important to stop or prevent bone destruction.
In the United States, nine out of ten women and nearly two-thirds of men do not get sufficient calcium. Currently many teens and young women do not consume milk or dairy products sealing their fate as adult women with weak bones. Consumption of soft drinks worsens the problem as phosphoric acid in colas increases urinary excretion of calcium. Women and teens who frequently follow calorie restrictive diets, or over exercise can adversely affect bone strength by decreasing normal fat dependent hormone levels including vitamin D and estrogen.
While adequate calcium and vitamin D are important to maintain bone strength, it may not be enough to protect against the rapid bone loss that occurs with menopause. Talk to your doctor about estrogen replacement therapy and new medications that may help preserve bone.
Calcium supplements should be consumed in two to three doses with no single dose greater than 500 milligrams (mg). It is important not to consume supplements with foods that hamper absorption. These include cocoa, spinach, kale, and unpolished rice. Remember that supplements are just that, a supplement to the natural food source of a vitamin. They should not be used in place of natural foods.
Food Sources that Boost Calcium Intake
Dairy products are by far the most common food source of calcium and supply seventy-five percent of all calcium in the food supply. Dairy is usually fortified with vitamin D and other nutrients as well. A number of food products today have additional levels of calcium and vitamin D including juices, cereals, and desserts. Many experts agree that the best source and utilization of calcium is via digested foods. (See the chart at right for calcium content in foods)
Research continues on the role of calcium in not only bone health, but also in the reduction of PMS symptoms, the reduction of blood pressure (the DASH study), the reduction of body fat, possible connections to sleep patterns and others. Take a moment to reflect on your personal eating style and see what you can do to improve this important mineral in your meal planning.
Pamela Cannoy Kelle, R.D., C.D.E., is a nutrition therapist and registered dietician. She is in private practice in Chattanooga. Pam works with individuals and groups with weight-related issues and diabetes. Her office is located in the historic Southern Saddlery Building at 3085 South Broad Street, Suite J, Chattanooga. She can be reached at 423-752-5207 or at firstname.lastname@example.org.