Calcium and Iron — In the Body and In the Diet

The most abundant macromineral in the human body is calcium, accounting for approximately 1.5% of total body weight.

In addition to being the most plentiful, it is also one of the most important minerals. Its main functions are in the growth, maintenance and reproduction of the human body. An astonishing 99% of calcium can be found in the bones and teeth with the remainder of calcium residing in both intra- and extracellular fluids.

Calcium, Diet, and Health

Sir Humphrey Davy of England was the first researcher recognized as isolating the impure metal form of calcium in 1808. However, calcium’s history is far older, with records dating from 975 AD, indicating the use of plaster of paris to set broken bones, and from the first century AD, when Romans prepared a lime mixture of “calx”. As a nutritional mineral, calcium is now known to play many essential roles in the body’s everyday functions.

One of its most important functions, is its action in muscular contractions which in turn helps to regulate the heartbeat and assist in the transmission of nerve impulses. Additionally, calcium has been found to be an integral component of proper blood clotting, of maintaining the walls of blood vessels, and in specific enzyme activation.

One of the current debatable topics on calcium questions the best sources of the macro-mineral. Calcium is naturally occurring in a variety of common foods including all dairy products, sardines, clams, oysters, tofu, turnip and mustard greens, broccoli, kale, legumes, and dried fruits. Although meats, grains and nuts do contain some calcium, they are considered poor sources. Looking at this list, one would assume that it would an easy task to obtain the recommended daily calcium levels. It turns out though, all calcium sources are not created equal, or so the research has shown.

One school of thought touts that dairy can contribute the recommend daily dietary calcium amounts, while others feel that dairy sources cannot be assimilated by the body as completely or as easily as the calcium from greens and legumes. To add to the difficulty of crowning one source the leader over the rest, other factors must be considered. For example, Vitamin D plays a role in calcium’s absorption, as does fiber, phytate, oxalate, magnesium, unabsorbed dietary fatty acids and phosphorous. Although the debate will rage on, especially as special interest groups continue to pay for the research being done, the terrible consequences of not getting the required calcium amounts is taking its toll on the western world.

Calcium deficiencies are a major public health concern for the aging population, osteoporosis being the most serious. According to the National Osteoporosis Foundation, an estimated 10 million Americans have the disease. Meanwhile, 55 percent of people 50 years of age and older are at risk of developing osteoporosis. This disease afflicts four times the number of women than men, probably due to changes in the body during menopause.

In conclusion, it makes sense to attempt to incorporate 1000 mg of calcium daily, the recommended dietary allowance (RDA) for adults aged 19-50 years old, by eating a wide variety of foods from the above list. Also, be sure to continue to monitor the latest research for changes and additions to the calcium story.


Iron is found in the human body in amounts of two to four grams with variations occurring depending on body weight, age, gender, pregnancy and state of growth. It is considered one of the microminerals of the body and is essential, meaning it must be obtained through the diet.

The recommended dietary allowance of iron for adult males, between 25 and 50 years old, is 10 mg. It is 15 mg for adult females, 19 to 50 years of age. During pregnancy, the requirement for women increases to 27 mg per day, while the recommendation for infants and children varies between 8 and 15 mg per day depending on their age and sex.

Iron, Diet, and Health

The human body’s need for iron is crucial. Without it, we would not survive. Over 65% of the body’s iron is found in hemoglobin, the protein in red blood cells. Iron is the center atom of this heme molecule and works to bind, and thus transport, oxygen molecules to all of the cells in our body. Iron also helps to store oxygen in the tissues and aids in energy production by taking part in the electron transport chain. Another function of iron is to be a part of many enzymatic reactions required by the body on a daily basis.

Iron in the body is found in two separate forms, the heme form and the non-heme form. The heme form is the “active” component helping with oxygen transport while the non-heme form is how iron is stored in the body tissues. Each form is best derived from different food sources. Heme iron can be found in animal meat products such as beef, chicken, turkey, pork and some fish and shellfish. The body gets its non-heme from plant sources – nuts, beans, fruits, vegetables, and grains. The heme form of iron is more easily absorbed by the body than the non-heme form.

There are numerous molecules that can decrease or increase the amount of iron absorbed by the body when consumed through the diet. For example, to increase iron absorption, it is recommended that foods containing iron be eaten jointly with foods containing vitamin C (ascorbic acid). The same goes for citric acid, lactic acid and tartaric acid (found in grapes, wine, cream of tarter and other fruits). Some sugars such as fructose and sorbitol also enhance absorption. Research is also showing that animal products containing cysteine, such as meat, fish and poultry, may increase the body’s absorption of iron.

On the other hand, foods that may hinder iron absorption include phytate (found in maize and whole grains), soy protein, oxalic acid (found in spinach, chard, chocolate, tea and other foods), phosvitin (a protein found in egg yolks), and several other nutrients such as calcium, zinc, manganese and nickel. In fact, there may be an astonishing 60% reduction in iron absorption if tea (containing phenolic compounds) is consumed after a meal while drinking coffee during or after you eat may reduce iron absorption by 40%, also due to its content of polyphenols.

Due to the increased production of red blood cells during pregnancy, the expectant mother’s demand for iron also rises. If the amount of iron consumed in the diet is not proportionally increased, a form of pregnancy induced anemia can result. Anemia can be detected through symptoms and/or routine blood tests. During pregnancy, a woman’s doctor may suggest taking an iron supplement in addition to augmenting the diet with good sources of iron.

Besides pregnancy, other lifestyle conditions may also cause iron deficiency anemia. Classic anemia symptoms include pale skin, fatigue, dizziness, shortness of breath, rapid breathing on exertion, heart palpitations, weakness and the inability to maintain a proper body temperature. Anemia can be caused by pregnancy, heavy blood loss such as trauma, internal bleeding, or heavy menstrual bleeding, poor absorption, interactions with foods or medications and lack of adequate iron in the diet. Women are more prone to anemia for several reasons, one being they have a smaller iron store than men, and second they lose blood through menstruation and have an increased need for iron during pregnancy. Anemia can be treated through decreasing any abnormal bleeding, providing adequate quantities of iron, folate and B-12 in the diet and monitoring any interactions that may be decreasing iron absorption.

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