Fundamentals of Human Nutrition/Calcium

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10.1 Calcium[edit]

10.1.1 Sources[edit]

Calcium is a very important mineral in human metabolism, making up about 1-2% of an adult human’s body weight. Contrary to popular belief, you do not need to eat dairy foods to get the calcium you need in your meal plan. (Calcium, n.d) Calcium is found most abundantly in milk, however for people that do not prefer to drink milk, calcium can also be found in high quantities in cheese and yogurt. Calcium can also be obtained through using dairy products in assorted prepared dishes. As stated in the opening quote though, there are plenty of other non-dairy options for fulfilling your body’s calcium needs. Tofu, corn tortillas, some nuts such as almonds, and some seeds such as sesame seeds all can supply calcium. A single slice of most breads contains only about 5-10% of the amount of calcium found in milk and dairy products, but by eating a lot of pieces of bread, the calcium adds up. Oysters and canned sardines are also good sources of calcium. Among the vegetables, those high in calcium include kale, watercress, mustard and turnip greens,broccoli, parsley, and bok choy. As far as beverages go, some mineral waters, as well as calcium-fortified orange juice and other fruit and vegetable juices can provide up to 500 milligrams of calcium in one liter and allow you to obtain other vitamins and minerals as well.

10.1.2 Functions[edit]

Calcium is the single most abundant mineral found in the human body. 99% of the bodies calcium can be found in bones and teeth and the other 1% is present in body fluids. There are two crucial roles calcium plays in the body, “First, it is an integral part of bone structure, providing a rigid frame that holds the body upright and serves as attachment points for muscles, making motion possible. Second, it serves as a calcium bank, offering a readily available source of the mineral to the body fluids should a drop in blood calcium occur.”(Whitney/Rolfes, 2011. Pg. 400) I will now break down the function calcium plays in bones, body fluids, disease prevention, and obesity. • Calcium in Bones: As bones are growing and beginning to develop, calcium salts called hydroxyapatite crystallize on a matrix of collagen. During the process of mineralization the crystals of calcium salt become denser which in turn gives strength and rigidity to the developing bones. • Calcium in Body Fluids: The mere 1% of calcium that is present in body fluids may not seem like much, however it is incredibly vital to life “The calcium in your body [fluids] plays key roles in cell signaling, blood clotting, muscle contraction and nerve function. Cells use calcium to activate certain enzymes, transport ions across the cellular membrane, and send and receive neurotransmitters during communications with other cells. As an electrolyte, or a particle that helps conduct electricity in the body, calcium is also one of the key players in maintaining regular heartbeat.”{Kamps, n.d.) • Calcium and Disease Prevention: The research that has been done in regards to the correlation between calcium and disease prevention is inconsistent and inconclusive although, from what has been found calcium may play a role in preventing hypertension, diabetes and colon cancer and in lowering blood cholesterol. • Calcium and Obesity: Again, studies have not been 100% conclusive however; there is some evidence that supports calcium aiding in maintenance of body weight. It has been found that consuming adequate amounts of dietary calcium may help to prevent excessive fat accumulation by stimulating hormonal action that targets the breakdown of stored fats.

10.1.2- Functions

Calcium, being the most essential mineral in the human body, is responsible for total body health. Along with total body health, calcium contributes to numerous functions in our bodies like blood clotting, nervous system functioning, enzyme function and strong bones and teeth. The body is regularly using calcium and its ions for the functions of the heart, blood, muscles, and nerves. (Evert, 2013) Also, calcium is known to prevent osteoporosis, a disease where bones become weak and brittle with age. Osteoporosis can lead to painful consequences like fractures of the spine and bones, causing pain and disability. (Wood, 2015) Researchers find, but it has not yet been proven valid, that calcium can also aid problems like PMS, high blood pressure, and weight gain. (Wood, 2015) Our bodies use almost all (99%) of the calcium we intake to support our bones, body structures, and teeth. This in turn, supports our bodies’ skeletal structure and how it functions. (Evert, 2013) Calcium helps the bones grow and remodel throughout a person’s life. Remodeling a process when the bones break down and are replaced with new bone. Without calcium, this important process would not occur. From birth to young adulthood, a person’s bones are in a constant growth phase. (Grossi, 2000) During this time, a person’s bones are increasing in size, length and width, so calcium is essential for proper growth. Also with the help of calcium, modeling occurs, which is the shaping of these growing bones. But calcium in the body can be lessened through every day bodily functions like waste/excretion, the shedding of hair and nails, and even perspiration. (Grossi, 2000)

The calcium that is not bone related, although it is a small amount, plays a key role in the functioning of the body. Calcium, plays a part in allowing our blood to clot by maintaining the solidity of fibrin. Additionally, expansion and contraction of blood vessels, hormones and nerve impulse transmission would not be functioning without the help of calcium. (Wood, 2015) Calcium is necessary for transmitting nerve impulses throughout the body along with various muscle contractions/relaxations. In our muscles, calcium ions are released to trigger the chemical reaction between myosin and actin. (Wood, 2015) This reaction then releases the energy from adenosine triphosphate (ATP), which is causes a contraction in the muscle. Then the ions that were released are retracted and the muscle then relaxes. This function, with the help from calcium, is especially vital to the function of the heart muscle and the way it contracts and relaxes. (Wood, 2015) Calcium is also has its involvement in brain development during the early stages of life and has the capability of regulating neuronal enhancement and can jump start adaptations in some brain cells. (Wood, 2015)

10.1.3 Requirements[edit]

The recommendation for how much calcium a person should consume has been set at an amount that will allow for a 30% absorption rate in the body. It is very important to get enough calcium in your diet as you are growing, this will ensure that the bones are all strong and dense. Calcium intake is generally high during the early years because bones are forming and then in the later years of life because bone loss begins. It is important to remember not to consume too much calcium, through the use of supplements for example, because this can have negative effects such as kidney stone formation.

10.1.4 Imbalance[edit]

In comparison to other nutrients calcium is very different in that regardless of the amount of calcium you obtain through your diet, blood calcium concentration remains relatively constant with the help of hormones. Blood calcium levels only change in response to abnormal regulatory control, NEVER diet. Maintaining calcium homeostasis involves the synchronization of hormones and vitamin D along with 3 important organs: the kidneys, bones and intestines. When blood calcium levels are too high this is considered calcium rigor, which results in muscles contracting and being unable to relax. Blood calcium levels that are too low is known as calcium tetany, which is characterized by uncontrolled muscle contractions. These increased or decreased levels are not caused by too much or too little dietary calcium consumption but rather by a lack of vitamin D in the diet or abnormal secretion of the regulatory hormones.


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Understanding Nutrition. Australia: Wadsworth, Cengage Learning, 2011. Print.


Evert, A. (2013, February 18). Calcium in diet: MedlinePlus Medical Encyclopedia.

Grossi, N. (2000). Major Functions of Calcium in the Body.

Wood, R. (2015). Micronutrient Information Center.