Most living things, including the human body, are made up of only 11 elements. We know the major elements, like hydrogen, oxygen, and carbon, but what about the lesser known trace elements? They, too, have vital tasks.
Everything living and inanimate in the universe is built of atoms – that is, the elements. The endless variety of substances in the universe consist of various compounds and mixtures, but they’re all built of only 92 natural elements. This number is much smaller if we deal with living things: only eleven elements (carbon, oxygen, hydrogen, nitrogen, sodium, magnesium, phosphorus, sulphur, chlorine, potassium and calcium) constitute about 99.9% of all living organisms.
The fact that the same element, although in different forms, has functions both in the living body and in inanimate matter is interesting. For example, an average 70 kg adult body contains 14 kg of carbon (C), which is the main component of both coal and oil. A human body, on average, contains 44 kg of oxygen (O2), the chief instigator of the respiratory system. Hydrogen (H), which is approximately 7 kg of a body, is used today as car fuel.
In a way, then, the human body is a pastiche of elements: it contains 2.1 kg of nitrogen (N2), 1 kg of calcium (Ca), 700 g of phosphorus (P), 170g of potassium (K), 140g of sulphur (S), 70g of chlorine (Cl), 70g of sodium (Na), and 30g of magnesium (Mg). More than 60 other elements are detected in the body in trace quantities, including gold, silver, and even uranium. (Trace quantities means as little as 100 mg – or, as big as four grains of rice.) These are usually ingested accidentally, often in food.
But our bodies need these trace elements. For example, a selenium (Se) deficiency may cause muscle weakness, a chrome deficiency may cause fatigue, and a lithium deficiency may lead to bipolar disorder.
The total percentage of these elements is about eight out of a thousand. The main trace elements in our body are chromium (Cr), cobalt (Co), copper (Cu), iodine (I), iron (Fe), manganese (Mn), molybdenum (Mo), selenium (Se), and zinc (Zn).
Trace elements are found in very small amounts in the human body. While the function of some trace elements in the body has not yet been fully understood, many of them have vital tasks.
100-150 mg of copper are found in the average adult human body. 65 mg are found in the muscles, 23 mg in the bones, and 18 mg in the liver. Copper moves through the blood after its absorption into the body and takes its place in the structure of some amino acids. Our daily copper need is 0.05 mg / kg in children and 3.5 mg / kg in adults. The main sources of copper are meat, shellfish, nuts, grains, and pulses. The main problems caused by a copper deficiency are excessive weight loss, bone disorders, anaemia, hair whitening, and irregularities in the heart muscles.
Iron is an indispensable element for the circulation of oxygen in the body. Smaller quantities of iron are found in the blood plasma, whereas larger amounts are found in the structure of haemoglobin. The amount of iron in adults is about 4 g, which is enough to make a small nail.
Iron is mostly stored in the liver, spleen, and bone marrow. How much iron a body needs varies according to age and person. Adult men and women need around 10 mg per day, while in women it increases to 15 mg during certain time periods.
Iron is found in food such as liver, other meat, beans, oats, and cocoa. The most important indications of iron deficiency are fatigue, shortness of breath, jaundice, headache, sleeping disorder, excessive tiredness, collapsed nails, and hair loss.
The average human body has 1.8 mg of zinc, which is found especially in the structures of the skin, prostate, bones, and teeth – though it can also be found in the kidneys, spleen, heart, brain, pancreas, and lungs in small amounts. Major zinc sources include unground cereal, pulses, spinach, lettuce, liver, eggs, milk, and dairy products. Zinc, which is found in the structures of some enzymes, plays an important role in the passage of vitamin A into the blood; it is also responsible for insulin secretion, and plays an active role in the growth and development of the body. A zinc deficiency results in forgetfulness, impaired genital development, weakening of the immune system, tissue problems in the skin, reduced mobility, and an impaired sense of smell and taste. The daily zinc requirement is about 12-15 mg.
The human body needs about 150 micrograms of iodine every day. Found in the body in the range of 20-50 mg, iodine is especially prevalent in the thyroid glands, the skin, and the skeletal system. The basic function of iodine in the body is assisting in the production of thyroid hormones. It is also used in the nervous system. Our main iodine sources are fish, other seafood, spinach, and rice. An iodine deficiency causes "goitre" disease. It also causes discomforts such as weakening heart rate and a slowing metabolism.
Cobalt element, the source of which is animal food, is found in the structure of the vitamin B12 and is stored in the liver. B12 is one of the most important vitamins for our body’s metabolism: it helps form red blood cells and thus makes us more energetic. It also is integral in the healthy functioning of the central nervous system.
One of the most critical tasks of trace elements is being part of the structures of enzymes. Enzymes are catalysts that speed up intracellular and extracellular biochemical reactions. These enzymes are involved in dozens of vital reactions. If the same reactions took place without enzymes, they would take a very long time and need very high temperatures.
Just as a deficiency of any of these elements can cause problems for the body, so can an excess of them. For instance, excess copper can cause cirrhosis, liver failure, or brain damage. Excess iron can lead to liver or other organ failure. Many of the trace elements, if consumed in excess, can lead to different kinds of cancers. If you suspect any of these problems, a doctor should be consulted, and all the trace elements should be consumed in moderation.
According to what our body needs, the amount of material that should be absorbed is encoded in our digestive system. The absorption process usually happens in the small intestine. Foods are first reduced in size by enzymes and bile salts from the stomach, pancreas, and liver. Later, during the journey through the intestines, the disintegrated molecules are absorbed into the blood. Of course, in this process, it is very important for specific molecules to absorb the right enzyme. Also important are the amount of specific enzymes to be secreted and how much of the element should be absorbed. All of this continuously happens in our bowels without our knowledge.
It’s quite remarkable: the elements we need are created in food, and the body has been specifically designed to break down these foods and extract exactly the elements our body needs. At the atomic level, we neither intervene nor know about the operations being performed with extraordinary precision. One can’t help but ask: how could all of this be so perfectly calibrated?
MN Chatterjea, Rana Shinde, Textbook of Medical Biochemistry, JAYPEE, 2012