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8.2: Minerals - Basic Concepts

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    Skills to Develop

    • Define the term "mineral" and understand how a mineral is different from a vitamin
    • Know the difference between major and trace minerals
    • For each mineral, know what the mineral does and what happens to the human body if: the mineral is too low in the diet for too long (deficiency); the mineral is too high in the diet for too long (toxicity) and be able to list some food sources that are rich in each of the minerals.
    • Describe factors that can decrease or increase the ability of the small intestine to absorb minerals into the blood

    From the beginning of this text we discussed the six classes of essential nutrients: Carbohydrates, Lipids, Proteins, Vitamins, Minerals and Water. You will recall that these nutrients can not be made by the human body, or can not be made in sufficient amounts, therefore we must take them in from the outside world. In this portion of Chapter 8 we will discuss the category of essential nutrients called Minerals, also known as Dietary elements or mineral nutrients. Minerals are naturally occurring chemical elements required by living organisms for survival. Many of the minerals we need are plentiful in a typical scoop of dirt! If fact, there is an illness called Pica, in which the affected individual has insatiable cravings to eat dirt. There is evidence that in at least some cases of Pica, the individual is low in minerals (like Iron) and somehow their body knows that they can get those minerals from soil! Of course there are dangers to eating dirt which might be contaminated with substances that are NOT edible. Because minerals are present in the Earth's crust, plants, which grow in the soil are often a good source of minerals though animals, who eat the mineral filled plants, can be good sources as well.

    There are two categories of minerals: Major minerals and Trace minerals. These two terms refer to how much of the mineral is needed in the diet and also by how much is present in the human body. Major minerals are needed in amounts greater than 100 mg per day; whereas Trace minerals are needed in amounts less than 100 mg per day. Alternatively, Major minerals are present in the body in amounts greater than 5 grams and Trace minerals are present in the body in amounts less than 5 grams. The major minerals are: calcium, phosphorus, potassium, sulfur, sodium, chlorine, and magnesium. Important trace minerals include: iron, cobalt, copper, zinc, manganese, molybdenum, iodine, bromine, and selenium. These are also called minor minerals, with "minor" referring to their amount, as opposed to their importance. 

    Over twenty dietary elements are necessary for mammals, and several more for various other types of life. The total number of chemical elements that are absolutely needed is not known for any organism. Ultratrace amounts of some elements (e.g., boron, chromium) are known to clearly have a role but the exact biochemical nature is unknown, and others (e.g. arsenic, silicon) are suspected to have a role in health, but without proof.

    Major and trace minerals have a variety of life sustaining roles in the human body. Some, like Calcium and Phosphorus, make up structures like bones and teeth. Others, like Sodium and Potassium regulate our fluid balance and blood pressure. Still others, like Magnesium, Zinc and Copper function as cofactors, which are minerals that must bind to specific enzymes in order for those enzymes to do their job. Many minerals have more than one function and families of minerals often work together doing related jobs in the body. As you read about each mineral below, try to figure out some of the primary functions of the mineral, what happens if you get too little of the mineral in your diet for too long (deficiency) and what happens if you get too much of the mineral in your diet for too long (toxicity).  

    Bacteria play an essential role in the altering of primary elements that results in the release of nutrients for their own nutrition and for the nutrition of others in the ecological food chain. One mineral, cobalt, is available for use by animals only after having been processed into complicated molecules (e.g., vitamin B12) by bacteria. Scientists are only recently starting to appreciate the magnitude and role that microorganisms have in the global cycling and formation of biominerals.

    Essential Elements

    Of the approximately 115 elements known, only the 19 highlighted in purple in Figure \(\PageIndex{1}\) are absolutely required in the human diet. These elements—called essential elements—are restricted to the first four rows of the periodic table, with only two or three exceptions (molybdenum, iodine, and possibly tin in the fifth row). Some other elements are essential for specific organisms. For example, boron is required for the growth of certain plants, bromine is widely distributed in marine organisms, and tungsten is necessary for some microorganisms.


    Figure \(\PageIndex{1}\): The Essential Elements in the Periodic Table. Elements that are known to be essential for human life are shown in purple; elements that are suggested to be essential are shown in green. Elements not known to be essential are shown in gray.

    At least twenty chemical elements are known to be required to support human biochemical processes by serving structural and functional roles as well as electrolytes.[1] Most of the known and suggested dietary elements are of relatively low atomic weight, and are reasonably common on land, or at least, common in the ocean (iodine, sodium). Here is an image of the Periodic Table of The Elements showing Sodium (Na), Iron (Fe), Calcium (Ca) and the other minerals.

    Note: Minerals are Inorganic

    Please note that Minerals are inorganic, meaning that they are not structures made with Carbon like the vitamins were. Think of an Iron rod, it is not made of Carbon, Hydrogen and Oxygen, it is only made of elemental Iron! Students often get confused about this point so re-read that a few times if it did not make sense.

    Mineral nutrients refers to the smaller class of minerals that are metabolized for growth, development, and vitality of living organisms. Mineral nutrients are recycled by bacteria that are freely suspended in the vast water columns of the worlds oceans. They absorb dissolved organic matter containing mineral nutrients as they scavenge through the dying individuals that fall out of large phytoplankton blooms. Flagellates are effective bacteriovores and are also commonly found in the marine water column. The flagellates are preyed upon by zooplankton while the phytoplankton concentrates on the larger particulate matter that is suspended in the water column as they are consumed by larger zooplankton, with fish as the top predator. Mineral nutrients cycle through this marine food chain, from bacteria and phytoplankton to flagellates and zooplankton who are then eaten by fish. The bacteria are important in this chain because only they have the physiological ability to absorb the dissolved mineral nutrients from the sea. These recycling principals from marine environments apply to many soil and freshwater ecosystems as well. 

    Dietary Nutrition

    Dietitians recommend that dietary elements are best supplied by ingesting specific foods rich with the chemical element(s) of interest. The elements may be naturally present in the food (e.g., calcium in dairy milk) or added to the food (e.g., orange juice fortified with calcium; iodized salt, salt fortified with iodine). Dietary supplements can be formulated to contain several different chemical elements (as compounds), a combination of vitamins and/or other chemical compounds, or a single element (as a compound or mixture of compounds), such as calcium (as calcium carbonate, calcium citrate, etc.) or magnesium (as magnesium oxide, etc.), chromium (usually as chromium(III) picolinate), or iron (as iron bis-glycinate).

    The dietary focus on chemical elements derives from an interest in supporting the biochemical reactions of metabolism with the required elemental components.[20] Appropriate intake levels of certain chemical elements have been demonstrated to be required to maintain optimal health. Diet can meet all the body's chemical element requirements, although supplements can be used when some requirements (e.g., calcium, which is found mainly in dairy products) are not adequately met by the diet, or when chronic or acute deficiencies arise from pathology, injury, etc. Research has supported that altering inorganic mineral compounds (carbonates, oxides, etc.) by reacting them with organic ligands (amino acids, organic acids, etc.) improves the bioavailability of the supplemented mineral.


    The term bioavailability refers to the ability of a body to extract a nutrient out of a food or beverage and effectively move it into the bloodstream for use in the body. Minerals are absorbed through the small intestinal wall like most nutrients and, like other nutrients, there can be factors that either decrease absorption and/or increase absorption of minerals. One example of increasing absorption of a mineral is the consumption of food containing Vitamin C (like citrus dressing) together with a food containing Iron (such as spinach). Combining these two nutrients in a spinach salad with citrus dressing for example, significantly increases the absorption of the iron present in the salad. Absorption can also be hindered by some factors in the diet. One example of decreasing absorption of minerals is the consumption of unleavened (no raising agents used) whole wheat flat-bread. Wheat bran contains compounds called phytates which tend to trap much of the zinc present in the bread. If a raising agent (like yeast) is used, the phytates release the zinc and it is available to be absorbed but if a raising agent is not used, much of the zinc remains trapped and will be excreted rather than being absorbed into the blood. Even the cooking method can impact how much of a mineral is available for us to absorb. If you have ever steamed broccoli, you've noticed the darkly colored water that collects beneath. Some of the water soluble minerals (as well as other water soluble nutrients) have been lost in the cooking water when you dump it down your drain. Finally, your own gastrointestinal health can greatly impact bioavailability. From teeth that chew inefficiently, to inadequate digestion, to small-intestinal walls that are inflamed and not very good at catching and absorbing nutrients, your entire GI tract can greatly influence how many of the nutrients from your food can make it into your blood stream. Most of the time the human body does a great job trying to compensate for increased and decreased bioavailabilty of nutrients but it is important to keep these concepts in mind if someone is eating a healthy diet but still having trouble getting appropriate blood levels of some nutrients.


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