Calcium – The Key To Strong Bones And Teeth
Calcium is chemical element with symbol Ca and atomic number 20. This mineral is more prevalent in the human body than any other mineral. The mineral is needed for healthy bones and teeth that must last our entire lives. Although the mineral is associated with the bones, it plays other important roles in the body, such as preventing hypertension, decreasing the odds for getting colon or breast cancer, improving control over our weight, and reducing the risk of getting kidney stones.
The functions of calcium also include muscle contraction, nerve impulse transmission, blood clotting and cellular metabolism. The mineral is also a natural tranquilizer, so drinking warm milk before bed is not a myth, it can actually due to the presence of the mineral help you to sleep.
The bones and teeth contain more than 99% of the mineral with the blood and soft tissues containing the other 1%.
Calcium Regulation in The Blood
The importance of the mineral to the body requires that blood levels are kept optimum, as a result there are three mechanisms that assist in maintaining appropriate blood levels of the mineral through regulation by the three hormones calcitriol (the active form of VitaminD), parathyroid hormone, and calcitonin.
These hormones control intestinal absorption of the mineral, release of the mineral from bone, and excretion of the mineral by the kidneys.
This is an expecially troubling mineral for women in menopause, since the hormone estrogen affects the balance of the mineral, when estrogen drops off significantly in menopause both bone reabsorption and a decrease in the absorption of calcium occurs.
Vitamin D increases reabsorption by the intestine, the active form of Vitamin D calcitriol increases the production of proteins that bind the mineral in the small intestine.
Parathyroid hormone (PTH) is secreted from the parathyroid gland when plasma levels of the mineral are too low. The hormone then acts on osteoclasts which break down bone to release the mineral and phosphorus back into the blood stream. PTH also increases reabsorption of the mineral by the kidneys and stimulates production of Vitamin D’s active form calcitriol.
When plasma levels of the mineral are too high calcitonin is secreted by the thyroid gland, and release of calcitonin acts to slow the actions of the other hormones preventing a huge release of the mineral into the bloodstream.
These three hormones act to keep the delicate balance of calcium in check in the blood stream and in the cells.
Growing children and adolescents are forming the basis for the strength of their bones that will last throughout their lives; failure to take in adequate amounts of the mineral can put young ones at risk later on in life for osteoporosis. Therefore, the AI for children and adolescents is 1,300 milligrams/day.
The adequate intake (AI) level is 1,000 milligrams/day for adults aged 19-50, and the AI for adults aged 51 and older is 1,200 milligrams/day.
Sources of the Mineral
Dairy products provide more than half of the daily requirement of the mineral, with nonfat milk and nonfat yogurt having the most density for the mineral. Cheese and ice cream are also good sources of the mineral but should be eaten in moderation due to their high fat content. The mineral is also available in processed tofu, kale, Chinese cabbage, turnip greens. There are also some brands of orange juice, cereal, and bread which are now fortified with the mineral.
The best way to obtain the mineral is of course through the foods we eat; however, for those that may be lactose intolerant and unable to consume dairy products there may be the need to take a supplement.
Too Little or Too Much Mineral
A lower level of the mineral in the blood known as hypocalcemia is relatively uncommon, but when it does occur, its causes can be related to kidney failure, parathyroid gland abnormalities, and vitamin D deficiency. If the deficiency is severe, then muscle spasms, facial spasms, and convulsions can result. Low intake can result in an increased risk for hypertension, colon cancer, and a complication of pregnancy known as preeclampsia which is marked by high blood pressure, edema, and protein in the urine.
In addition, a chronic deficiency of the mineral in the diet can result in osteoporosis through suboptimal bone growth in childhood and adolescence or increased bone loss after menopause.
When there is too much mineral which is known as hypercalcemia then the causes are cancer and overproduction of PTH by the parathyroid gland. However, excess supplementation of the mineral usually does not result in hypercalcemia. The symptoms of hypercalcemia can be fatigue, confusion, constipation, and loss of appetite.
For more information about calcium click on the link to ods.od.nih.gov
For other information on nutrition some great references are:
• Nutrition – Fourth Edition by Paul Insel, Don Ross, Kimberley McMahon, and Melissa Bernstein
• The Vitamin Alphabet – Your guide to vitamins, minerals and food supplements by Dr. Christiana Scott-Moncrieff MB, CHB, MFHOM
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