Fundamentals of Human Nutrition/Calcium
10.1 Calcium[edit | edit source]
10.1.1 Sources[edit | edit source]
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. 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 many of these types f food sources, 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 | edit source]
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) We will now look at the function of calcium 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.
Calcium is one of the many important major minerals, essential to a human body. According to Medline plus “Calcium is the most plentiful mineral found in the human body. The teeth and bones contain the most calcium. Nerve cells, body tissues, blood, and other body fluids contain the rest of the calcium.” Calcium helps us maintain bone strength and tooth structure while creating a foundation for skeletal function. While 99% of calcium helps make our bones strong, the other 1% plays an essential role in blood clotting, cell signaling, nerve impulse transmission and muscle contractions. Some of the best food sources for calcium are: Dairy products, Fortified foods, greens, and calcium-processed tofu. While consuming calcium, our body needs to make space for it in our body. Some food sources that will increase the absorption of calcium in our body include growth hormones, vitamin D, and Lactose. While making sure you get enough calcium for your body, you must not exceed the calcium intake for your body. Effects of calcium excess could result in increased risk of oxalate-type kidney stones or interference with absorption of other minerals. The recommended amount of calcium intake varies for each age group. From 14–18 years of age, the recommended calcium intake is 1300 mg/day. Between the ages of 19-50, the recommended intake is 1000 mg/day. For 50+ the calcium intake is 1200 mg/day. Since you have made sure you are not surpassing the calcium intake, you must make sure to meet the recommended value daily. If non-sufficient calcium is received in our bodies, it will lead to osteoporosis. According to Worth “By having an adequate intake of calcium, you’re giving your body the building blocks to fuel all its important functions, as well as to knit new bone tissue. If you don’t get enough calcium, the body will “steal” calcium that’s stored in bones to make sure it has enough to meet the body’s needs.” Calcium deficiency is not to be taken lightly as it affects total bone mass. Other effects of calcium deficiency are ineffective blood clotting and hypocalcemic tetany (muscle spasms). A person with minimal to no calcium in their system, can have excessive bleeding from cuts or slits or in rare cases, death. Most people automatically associate calcium with bone; which is not wrong, but should not be limited to one source. According to Kamps “Calcium can affect how your body absorbs and uses other nutrients. In nature, calcium carries a very small electrical charge, which is why it can conduct electricity within your body.”
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 | edit source]
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 | edit source]
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.
10.1.5 Deficiency[edit | edit source]
Calcium deficiency can cause significant development problems, especially in the years of high growth during childhood and adolescence (Committee on Nutrition, 1999). Low calcium intake during these years will not allow for maximal peak bone mass to develop. Peak bone mass is reached in the majority of people by their late 20s, but a calcium deficient person will struggle to develop this high bone density needed to protect against fractures and the bone loss that develops with age (Whitney & Rofles, 2016). In addition to problems developing later on in life, infants and children who are deficient in calcium have an increased risk of developing rickets. Low calcium in adolescents is a risk factor for bone fractures (Committee on Nutrition, 1999).
Insufficient calcium intake rarely causes immediate symptoms because the body is able to regulate its blood calcium levels by using the calcium in bone (“Calcium,” 2013), which contains 99% of the body’s calcium (Whitney & Rofles, 2016). Over time low bone mass, called osteopenia, will develop if the body is forced to continue getting its calcium from the bones. Bone loss with age is a normal occurrence, so people who are unable to develop peak bone mass and build dense bones earlier in life due to calcium deficiency will have less protection against this natural bone loss (Whitney & Rofles, 2016). This leads to osteoporosis in adults, where the bones are so weak and porous that they can break under a normal stressor (“Calcium,” 2013).
When blood calcium levels are abnormally low, ineffective blood clotting and calcium tetany can occur. Calcium tetany causes muscle spasms, which relates to calcium’s vital role in muscle contraction and relaxation. It is important to note that these conditions are not caused by a lack of dietary calcium. They are due to low vitamin D or a problem with regulatory hormone secretion, which results in a low blood calcium concentration (Whitney & Rofles, 2016). Calcium potentially protects against certain chronic diseases, so a deficiency could lead to an increased risk of developing a condition such as hypertension (Kaluza & coauthors, 2010; Reid & coauthors, 2010). In more extreme cases, the deficiency can cause a numb, tingling sensation in the fingers and even irregularities with the heart rhythm (“Calcium,” 2013).
It is important to remember that a diet low in calcium will negatively affect the bones, not blood calcium levels. As you learned above, if the body is not receiving enough dietary calcium, it will take what it needs to supply the blood from the bones. High calcium recommendations are set in place to not only provide the body with a sufficient calcium supply, but to ensure the bones will receive enough to be able to reach their peak bone mass (Whitney & Rofles, 2016).
Sources[edit | edit source]
Calcium. N.p., n.d. Web. 3 July 2015. http://www.whfoods.com/genpage.php?tname=nutrient&dbid=45
Calcium. (2013, March 19). Retrieved December 1, 2015, from https://ods.od.nih.gov/factsheets/Calcium-Consumer/#h5
Calcium Requirements of Infants, Children, and Adolescents. (1999). Pediatrics, 104(5). Retrieved December 1, 2015, from http://pediatrics.aappublications.org/content/104/5/1152#ref-7
"Role of Calcium in the Body's Nutrition." Healthy Eating. N.p., n.d. Web. 3 July 2015. http://healthyeating.sfgate.com/role-calcium-bodys-nutrition-1265.html
"Calcium Intake." Steinsieker. N.p., n.d. Web. 3 July 2015. http://www.steinsieker.com/calcium-everyday/calcium-intake/
Understanding Nutrition. Australia: Wadsworth, Cengage Learning, 2011. Print.
I.R. Reid and coauthors, Effects of calcium supplementation on lipids, blood pressure, and body composition in healthier older men: A randomized controlled trial, American Journal of Clinical Nutrition 91 (2010): 131-139.
Kaluza and coauthors, Dietary calcium and magnesium intake and mortality: A prospective study of men, American Journal of Epidemiology 171 (2010): 801-807.
Whitney, E., & Rolfes, S. (2015). Understanding Nutrition (14th ed.). Stamford: Cengage Learning.
References[edit | edit source]
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.