Calcium
Overview
Calcium is the most plentiful mineral found in the human body and plays a large role in keeping the body functioning effectively. Calcium is significant in maintaining heart and bone health. While calcium is found in teeth and blood, the majority of a human’s calcium, about 98 percent of it, is found in the bones. Unsurprisingly then, calcium deficiencies most prominently affect the bones, often resulting in conditions such as osteopenia and osteoporosis. Because of the risk of these and other conditions, it is very important that all people, especially children, adolescents, pregnant and nursing women, and elderly men and women sustain appropriate calcium intake. Healthy levels of calcium can be maintained through a nutritious diet of foods rich in calcium, as well as calcium supplements.
Sources of Calcium
Most dairy products are rich in calcium. Milk is a wonderful source of calcium, and also contains lactose, protein, and fat, all of which help the body better absorb calcium. However, too much protein and fat in the diet can also limit calcium absorption. Yogurt and cheese are other dairy products that provide good sources of calcium. Many green, leafy vegetables, such as kale and broccoli, are also rich in calcium, as are nuts and seeds, including almonds and sunflower seeds.
Calcium supplements are available for people who do not get enough calcium through their diets alone or whose bodies otherwise have difficulty absorbing and maintaining healthy levels of calcium. There are many calcium supplements available, all with varying benefits and drawbacks. Calcium citrate and calcium lactate, for example, contain somewhat low levels of calcium, but because they dissolve easily, almost all of the calcium in the supplement is usually absorbed by the body. Other supplements, such as bone meal, dolomite, and oyster-shell calcium may be good sources of the mineral; however, they are believed to contain high levels of lead.
Calcium supplements are better absorbed when there is acid present in the stomach, which allows the supplement to dissolve and the calcium to be extracted. Although eating creates acid within the stomach, taking a calcium supplement with a meal is not always the best option because certain foods may block calcium absorption. Therefore, it may be best to take calcium supplements between meals with a light snack.
Functions of Calcium
Human bones consist primarily of a material that results from the combination of calcium and phosphorus, calcium phosphate, with about two and a half times more calcium than phosphorus. Calcium intake is extremely important for children and adolescents as these growth periods are crucial in the establishment of bone mass. Through childhood and adolescence, the body absorbs about 50 to 70 percent of ingested calcium; this calcium is used to help the bones grow larger and denser. Calcium absorption decreases with age: adults absorb only about 30 to 50 percent of ingested calcium. Adults also begin to lose bone mass as they grow older, which is why it is so important for them to maintain healthy levels of calcium; between the ages of 30 and 35, the body begins to lose bone mass more quickly than it can regenerate it. Continued calcium absorption will help adults maintain a healthy bone mass and prevent conditions such as osteopenia and osteoporosis.
The calcium found in the bloodstream contributes to the maintenance of many bodily functions, including heart health. Calcium in the blood helps with muscle contractions, regulation of the heartbeat and blood pressure, and helps nerve functioning by indirectly aiding the generation of neurotransmitters.
Calcium is only able to function so well when there are other factors in place that help the body make use of the mineral to its full potential. Vitamin D helps the body absorb calcium and works alongside the mineral within the body: it regulates the amount of calcium in the bloodstream and helps bones retain the calcium that is crucial to bone health. Magnesium is another important factor in calcium functioning as it helps maintain the solubility of the mineral; in turn, humans should have about half as much magnesium as calcium. Furthermore, Vitamins A and C, as well as exercise help the body absorb calcium.
While phosphorus is a key player alongside calcium in bone structure, the amount of phosphorus in the body needs to be maintained at a certain level. Too much phosphorus in the body can actually counteract calcium intake by causing calcium to be eliminated rather than absorbed properly; in turn, there should be about equal amounts of calcium and phosphorus in the body.
Uses of Calcium
Calcium plays a significant role in keeping the body healthy, even beyond bone health. Calcium seems to be a substantial factor in the maintenance of a healthy heart: while it is essential for proper functioning of the heart, calcium also lowers blood pressure and may reduce the risk of heart attacks and strokes. Studies have also shown that increased calcium intake helps ease the symptoms of premenstrual syndrome (PMS).
Calcium may also help prevent certain types of cancer. People who have higher levels of the mineral in their bodies have a lower risk of developing colon cancer. Calcium also seems to prevent re-growth of colorectal polyps.
There is some debate over the role calcium plays in the development of kidney stones. Traditionally, doctors thought that calcium was a main factor in the formation of kidney stones, and so discouraged calcium intake in patients prone to such a condition. More recently, however, studies have shown that higher levels of calcium in the body may actually lower a person’s risk of developing kidney stones.
Calcium Deficiency
Factors besides a diet lacking in calcium can contribute to calcium deficiency. For example, there are quite a few prescription drugs that prevent the body from maintaining healthy levels of calcium: antacids and drugs meant to supplement the body’s steroid production may lead to bone loss, while cholesterol medicines hinder calcium absorption. Alcohol use also hinders the body’s absorption of calcium.
Perhaps the most well-known result of calcium deficiency is the development of bone-weakening diseases including osteopenia or osteoporosis. Osteopenia and osteoporosis both develop when there is not enough calcium in the body to maintain healthy bones. While calcium exists in both the bloodstream and the bones, if there is not enough calcium in the blood, the body will begin to pull calcium from the bones. If calcium intake is not high enough, the body cannot replenish the calcium lost from the bones and the bones will become very weak. This condition is much more likely to develop as people age and their bodies are less able to replace calcium in the bones. People over 50, especially post-menopausal women, are at the greatest risk of developing these conditions.
Calcium deficiency is not just a problem for adults, however; since childhood and adolescence is the prime time for bone development, insufficient calcium and therefore insufficient development of bone mass during these years can set a person up for the more dangerous conditions later in life.
Required Daily Amount
Sufficient calcium intake is important for everyone; however, it is perhaps most important for children and adolescents, pregnant and nursing women, and elderly men and women, specifically postmenopausal women. While children and adolescents are still building bone mass, a process that requires calcium to continue effectively, pregnant and nursing women and elderly men and women are at a higher risk of losing bone mass and being unable to replace it; in turn, it is extremely important for these populations to maintain healthy levels of calcium in order to prevent the development of serious health conditions.
Infants from birth to six months of age are recommended to have 400 milligrams of calcium daily; between six months and one year of age, the recommendation increases to 600 milligrams. Children between the ages of one and 10 should have 800 milligrams of calcium daily, while adolescents and young adults between the ages of 11 and 24 are recommended to have 1,200 milligrams. After age 24, the recommended calcium intake drops to 800 milligrams. Because pregnant and nursing women may have trouble maintaining healthy levels of calcium, the recommended intake for them is increased to 1,200 milligrams.
References
- Alan H. Pressman and Sheila Buff. The Complete Idiot's guide to vitamins and minerals, Alpha A member of Penguin Group (USA) Inc (2007)
- Brewer, S. The essential guide to vitamins, minerals and herbal supplements, Right Way (2010)
- Elson M. Haas, Md & Buck Levin, Phd, Rd. Staying Healthy with Nutrition: The Complete Guide to diet and nutritional medicine, Celestial Arts (2006)
- Holford, P. The optimum nutrition bible, Little Brown Group (2004)
- Holford, P & Lawson, S. Optimum Nutrition Made Easy How to achieve optimum health, Piatkus Books (2008)
- Lieberman, S. & Bruning, N. The Real Vitamin & Mineral Book, Avery, a Member of Penguin Group (USA) Inc (2003)
- Rodale Health Books. Healing with vitamins : the best nutrients to slow, stop, and reverse disease, Rodale, (2009)
- Royston, A. Vitamins and minerals for a healthy body, Heinemann Library, (2003)
- The National Research Council. Recommended Dietary Allowances, 10th ed, National Academy of Sciences (1989)
- Werbach, M. Nutritional Influences on Illness, 2nd ed, Third Line Press (1993)
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