When we reviewed basic chemistry principles in our section on carbohydrates, we reviewed the term element, a specific type of atom. Minerals are elements (atoms of a particular type, ie., calcium) which serve a variety of functions.

 

Mineral comes from the term mine. Things that were worth mining, were termed minerals. Thus, we can see that the term "minerals" is a rather loose term. In medicine and nutrition we use the term "minerals"to refer to a specific number of elements that we benefit from.

Minerals are also termed "inorganic substances" or "inorganic elements". Inorganic means that they do not contain the element carbon. This of course, is obvious, if a mineral were always a single atom. And using the word "inorganic" in this sense, is true. However, keep in mind that all minerals are not composed of single elements. Calcium, a required mineral, is not found on its own in nature, but bonded to atoms of other elements, forming molecules. These molecules found in repetition in a considerable amount are also referred to as minerals because they were economically viable to mine from the earth, hence the term mineral. Calcium carbonate, CaCO₂ (limestone) also happpens to be a source of calcium in the food chain. Calcium carbonate contains the mineral calcium. But did you notice that the molecule, calcium carbonate contains carbon as well? Molecules that contain carbon are termed "organic", as compared to inorganic (no carbon). However, when molecules such as calcium carbonate are broken down, elemental calcium is released. The terms "organic" and "inorganic" overlap in certain respects. Learning the different ways these terms are used is an important tool in understanding the chemistry of what you consume. Because we never consume a pure inorganic element, but rather complexes. We rely on our metabolism to ultimately break down these complexes, thereby releasing the inorganic mineral(s).

 

Thus far, we see that minerals are single atoms, such as calcium, chromium, magnesium, etc., which are required by humans for various metabolic processes. As discussed above, although it is the single atom that we require, these are usually complexed with other atoms, forming molecules. It is in our body, that the molecule is degraded, releasing the elemental calcium, chromium, and other required minerals. Chromium is required in the diet for optimal functioning of growth hormone, insulin and probably other hormones. Calcium provides compressional strength to bones. Every mineral has a particular set of functions, as we shall see.

Keep in mind that minerals can harm us as well. Although chromium is a required mineral in the diet, high levels are known to be carcinogenic. Excessive high doses of calcium can deposit in blood vessels and organs causing calcification (hardening), decrease in organ function, mental depression, muscle weakness, fatigue, and other side effects.

We must equally consider deficiencies as well. Chronic inadequate amounts of calcium are contribute to decrease in bone strength and hence increases in bone fracture, and tooth decay. Calcium deficiency at any period can cause tetany, depression, heart conduction anomalies, and other neuromuscular excitability defects. Therefore, balance of minerals as well as all nutrients is of obvious value.

The average male is composed of approximately 6% minerals by weight. Let's look at the chart below.

The mineral component of the human body is derived from various amounts of at least* 19 different minerals.

Each of these minerals has their own specific set of functions, such as cofactors in hormones and enzyme-catalysed reactions, acid-base balance, nervous tissue conduction, muscle contraction, structural functions, oxygen transport, and others. Each mineral is required in certain amounts, from micrograms to grams. Minerals that are required in very small amounts (micrograms) are referred to as trace minerals.

Calcium-(Chemical symbol, Ca) Calcium (along with phosphorus) are the most abundant minerals in the human body. As we discussed in the introduction to minerals, calcium, as with other minerals, is needed in elemental form, but is mostly ingested in the body in the form of complexes. Once elemental calcium is released in the body, it is then incorporated into 1 of 2 possible forms. Most of the calcium in the human exists as calcium phospate crystals, in the bones and teeth. The calcium phosphate crystals in teeth and bones forms the cement that gives strength to them.

The other form of calcium existing in the human is pure elemental calcium, Ca⁺²(Click here for an explanation of the Ca⁺², which is called the ionic form of calcium). This ionic form functions in helping nerve impulse conduction, muscle contraction , ion transport, and signals across membranes.

Like all the chemicals that enter the body, a strict control of concentration must be maintained. If amounts of calcium (or any substance) were allowed to accumulate unchecked, illness would result. If too much calcium is voluntarily taken (eg., excess supplements) this could result in mental depression, muscle fatique, stomach cramping, and other symptoms. If calcium levels were allowed to fall too low, then depression, muscle spasm, nervous excitation, palpitations and other symptoms develop. Therefore, the body always attempts to keep the level of calcium constant. How does the body do this?

If calcium levels fall too low, then the body responds by excreting a hormone called parathyroid hormone (PTH), into the blood. PTH functions by increasing the absorption of calcium from the kidney(s). At the same time, PTH allows the kidney to shed phosphates in the urine. This helps to retain calcium, as we shall see. The reason PTH works on the kidney to retain calcium, is simply because calcium is transported throughout the body, via the blood. Some of the calcium in the blood is removed by the kidney and excreted in the urine. When the kidney begins to remove too much calcium, then PTH is secreted to stop this calcium loss. PTH is produced in the 4 parathyroid glands, which lie behind the thyroid gland.

PTH also increases the production of 1,25-dihydroxycholecalciferol. Don't let this word scare you, it's simply the chemical name for the active form of vitamin D. And as you may know, the function of this vitamin is to help in the uptake of calcium from the intestines (when you eat a meal). The active form of vitamin D also causes some of the calcium stored in your bones to exit the skeletal space and enter the blood. This brings the blood level of calcium back to normal. Keep in mind, that bones not only support your body and protect you, but also store extra calcium, for times when you need it. Since, your body is aware that it needs more calcium, it releases this PTH, and PTH goes to work, causing vitamin D production, and affecting the kidney to conserve calcium. It's that simple.

If we happen to have too much calcium in the blood, the body tries to alleviate this situation by doing several things. First of all, as you can figure, PTH, and vitamin D are no longer needed because they will only mobilise more calcium in the blood and we don't want that. We want it lowered, since it's too high now. The body reacts to this situation by secreting yet another hormone (there's a hormone for everything ! How about one for nagging housewives and husbands?). This hormone is called calcitonin and is secreted by special cells of the thyroid gland. Calcitonin decreases the resorption (taking away) of calcium from the bone and increases the loss of calcium and phosphate in the urine. By excreting excess calcium in the urine, the body is getting rid of the extra. This brings calcium levels back down to the normal range.

Calcium can be found in milk, dairy products, and calcium supplements (tablets), typically in the form of CaCO₃, (calcium carbonate), calcium lactate, or calcium gluconate. You may see different brands of calcium, such as oyster shell calcium, etc. The fact is, calcium is calcium, whether is comes from an oyster shell or a housebrick. The difference in brands is in the absorption and utilisation. For example, calcium complexed in different ways renders it more difficult to be absorbed. This is the logic in some of the more expensive calcium supplements. But do not let price lead you in the wrong direction. Remember, calcium is complexed in different forms. Some are better absorbed than others. Dietary calcium can be obtained from milk, milk products, and calcium supplements. Supplements typically contain calcium in the form of calcium carbonate (CaCO₃), calcium gluconate, or calcium lactate. In other words, a calcium atom is bonded to either carbonate (CO₃, gluconate, or lactate. But which one is absorbed the best?? Well, remember, calcium is absorbed in the gut, and vitamin D aids in its absorption. The best absorbed form seems to be oyster shell. But if you drink enough milk and consume other calcium containing foods, you are most likely obtaining sufficient amounts of calcium in your diet. Remember, too much calcium can cause stomach pains, mental depression and other uncomfortable symptoms, so keep it moderate.

Calcium is not contained in sufficient quantities in the multivitamin. This is understandable, as it would make the size of the vitamin as large as a marble, and you wouldn't want to swallow that (or would you?). Therefore, calcium has to be made into a separate tablet. Calcium is usually combined with vitamin D. Vitamin D is usually always added because of its function-to increase the intestinal absorption of calcium. You will see different RDA's (recommended daily allowances) in different countries. You will see RDA's range from 500mg/day, up to 800mg/day. With increased activity, supplemental calcium is needed, especially for lifting heavy weights, etc. Keep in mind that bones can thicken over time when subjected to weightbearing. Logically, calcium is needed.

During the menopause (period of cessation of menstruation in women) a chronic deficiency of calcium seems to accelerate the loss of bone mass. This occurs between 35 and 42 years of age. This advanced resorption of bone in postmenopausal (post= after) can lead to osteoporosis. Osteoporosis is a condition characterised by the increased occurence of bone fractures (hip, wrist, head of femur), and is a leading cause of disability amongst the older generation. Our studies show that increased calcium combined with exercise reduces bone fractures and increased calcium uptake by the bones.

Phosphorus-(Greek phosphoros 'bearer of light'). Phosphorus is a highly reactive nonmetallic element. It occurs in nature as phospates, commonly in the mineral apatite. Phosphorus is an essential element in the diet, being part of many molecules in the human, such as ATP (adenosine triphosphate) Phosphorus is a major component of the mineral phase of bone and is present in large quantities in all tissues, and is involved in virtually all metabolic processes.

 

Therapeutically, phosphorus was used in the treatment of rickets, osteomalacia, scrofula, tuberculosis, and central nervous system diseases. Of course, these historical treatments were unsuccessful and sometimes caused significant illness. Pure phosphorus is poisonous and highly inflammable, and consumption causes fatty degeneration of the liver and other organ/tissues. Inhalation of its vapour causes necrosis (tissue death) of the mandible (lower jaw)

 

We obtain significant amounts of phosphates in our diet, considering phospates are major constituents of plant and animal cells. Many food manufacturers also use phosphates as food additives for several reasons. Therefore, the consumer obtains a fair amount of phosphates in the diet.

 

In several countries there is no RDA for phosphorus, although in the US, the RDA of phosphorus is roughly equal to that of calcium, except during infancy. 800mg/day is an adequate amount for normal metabolism. Considering, foods that are high in calcium and protein are also high in phosphorus, we usually obtain sufficient amounts of phosphorus with consumption of these foods.

 

Deficiencyt states of phosphorus are rarely seen because of the abundance of phosphorus in foodsstuffs. Cases where large amounts of aluminum hydroxide antacids have been ingested, have resulted in phosphate definciency through binding with dietary phosphates and thus impeding their absorption. Additionally, kidney malfunction can also lead to phosphate depletion by increased renal (kidney) excretion, with signs of muscle weakness and bone pain.

Sodium (symbol= Na⁺, latin for 'Natrium')-A soft, silver-white alkaline metallic element. Sodium is the primary cation (positiv ion, as compared with negative ions or anions, such as chlorine) of extracellular (outside or external to the cell) fluids.

 

Sodium is essential in the diet, as will be discussed. Salts of sodium are widely used in medicine, the food industry, cosmetics, and for many other purposes.

Sodium acetate, the acetic acid (vinegar) combination with elemental sodium, is used as a source of sodium ions (positively or negatively charged atoms) in solutions for haemodialysis (hemodialysis, US spelling) and peritoneal dialysis. It is also used as a urinary alkalizer, diuretic and expectorant. Sodium alginate, is a carbohydrate of seaweed containing sodium, and is used as a thickening agent and suspending agent in foods and cosmetics. But of course, these products are combined with elemental sodium.

Sodium on its own is essential in the diet for many reasons. Sodium along with potassium and chloride function together in maintaining pH (acid-alkaline conditions) and in regulating osmolarity of intracellular (inside the cell) and extracellular (outside the cell) fluid. Sodium is involved in transmission of nerve impulses, and helps to maintain blood volume, and fluid voiume in other fluid compartments (see water).

Sodium is exreted by the kidneys through the formation of urine. We also lose sodium through sweat. Relocating to a warmer climate causes an individual to lose more sodium through the sweat glands than he or she lost in the colder environment. If individuals relocating to warmer environments participate in intense physoical activity, large amounts of sodium (and water) are lost through the sweat glands, resulting in dehydration, and/or health risks. However, if we allow our body to acclimatise to the warmer environment over the period of a few weeks, we will not lose as much sodium and water through sweat. Why is this?

The average individual can lose anywhere from 500-700ml of sweat each hour, in warmer climates and through exercise. Sweating (losing water and salts) is beneficial because the water in sweat becomes warm and ecaporates from the skin removing excess body heat, and thus keeping body temperatures within safe limits. As a person remains in warmer climates, they begin to sweat more profusely, sweating up to 2 litres each hour! This means that an indiviudal can lose up to 30 grams (1 ounce) of salt per day ! OF course, this does not benefit the body, as we can see that we need salt (sodium and chloride) to live. Therefore, the body attempts to rectify salt loss by increasing the production of a hormone called aldosterone. ALdonsterone is a steroid hormone produced by adrenal glands, a pair of glands which are positioned above the kidneys. When salt concentration becomes low, the body can detect these changes in concentration. As a result, several chemical messengers are produced in different areas of the body. These chemical messengers have a direct and indirect effect on the adrenal gland. Upon stimulation, the adrenal gland is prompted to produce and secrete aldosterone. One of the functions of aldosterone is to decreasethe amount of salt (and thus water) lost in sweat. Thus, this feedback control mechanism is but one of the many wonderful biological control sweithces to help the human survive (see homeostasis. This information can benefit anyone travelling to a warmer climate, especially those who plan to participate in mountaineering, hiking, trekking, or any other strenuous activity, because by allowing the body to acclimatise for a period of several weeks, this allows the aldosterone effect to occur and decrease the amount of salt and water loss from the body. This is important not only for peak performance during sporting events, but more importnntly for maintainence of health. As we will learn, there is also a danger to potassium levels as well in regards to prolonged heat exposure.

 

An established RDA of sodium has not been reached yet. Of course, this is a touchy area anyway, considering the relation to sodium and hypertension (higher than the normal average blood pressure). Additionally, western diets supply more than adequate amounts of sodium, on occasion, supplying excessive amounts. For example, average American diets deliver approximately 12 grams of salt per day (8 grams in food and 4 grams added).

 

Excessive amounts of salt temporarily raise the blood pressure (the pressure of blood against the blood vessel walls). This, of course, is a concern, considering that increased blood pressure against the walls of blood vessels can damage them. Additionally, the wall can rupture, leading to haemorrhage, or stroke. Sodium raises blood pressure by attracting water into the blood, and therefore, increasing blood volume. If there is a higher blood volume in the compartment of blood vessels, this will lead to a higher pressure to accomodate the excess fluid portion of the blood.