If you had to worry about providing your body separately with each individual mineral that it needs, you would have your time well filled. Fortunately, all the necessary minerals (almost always in the form of chemical compounds) are present in a well-balanced and varied diet and the need to boost intake with a particular mineral supplement is rare. Sometimes, for example, a patient with anaemia is given medication containing supplementary iron. There are more than 40 different minerals present in your body and each one fulfils some important function, even if nutritionists have not yet identified their exact roles.
Why we need minerals
Unlike vitamins, which are organic substances that help chemical reactions in the body, minerals are inorganic-substances with a wider variety of functions. For example, there are minerals that play a role in the regulation of body fluids, the osmotic pressure and the acidity of the blood; there are minerals that form structural parts of tissues, hormones and enzymes; and there are minerals that allow electrical currents such as nerve impulses to pass through the body. Many minerals are needed in comparatively large amounts. These include calcium, phosphorus, sodium, chlorine, potassium, sulphur and magnesium. Minerals that are essential but only needed in minute amounts are known as ‘trace elements’. These include iron, copper, iodine, fluorine, zinc, manganese, chromium and cobalt. The major chemical elements in the body – carbon, hydrogen, oxygen and nitrogen -supplied through proteins, carbohydrates and fats are not regarded as minerals.
Negative effects of minerals
Some minerals, safe in normal quantities, can be harmful if taken far in excess, but much more serious is poisoning caused by pollution of foodstuffs, water or the atmosphere with harmful minerals. Lead and mercury attract particularly close attention with regard to theirlevels in food and the air. When taken into the body, they may accumulate and produce unpleasant and dangerous symptoms such as severe abdominal pain, paralysis or other nervous disorders, and mental disturbances.
Lead poisoning comes mainly from car exhaust fumes, both directly, by being breathed in, and indirectly in foodstuffs grown in areas of high atmospheric lead pollution and in milk from cows grazing in such areas. In the same way, mercury poisoning can occur as a result of eating foodstuffs grown on land contaminated by mercury, or by eating fish which absorb industrial mercury-containing wastes emptied accidentally or deliberately into the sea.
Vitamins are organic chemical compounds that must be present in small quantities in the food we eat in order to maintain a good health. Some vitamins are present in food in the form in which they are required. Others are taken into the body as provitamins, precursors that in the body are converted into vitamins proper. The action of ul-traviolet light (from the sun) creates vitamin D in the skin in this way. Still others, such as biotin and vita-min K, are synthesized by intestinal bacteria within the body. Each kind has its own function in the metabolic system in which, unlike proteins, carbohydrates, fats and minerals, they do not serve as building material or fuel. Consequently, vitamins, so-called because they were originally regarded as ‘vital amines’, could be re-named ‘metabolic regulators’. Although the body has a great quantity of vitamins at its disposal, a stock that would not be exhausted for four to twelve months after the supply had stopped, a regular supply is of great importance in order to prevent the occurrence after some (usually fairly long) time of serious deficiency symptoms. It is, however, too easy to assume that, because vitamins are good for you, more vitamins are better. Unfortunately, the adage ‘too much of a good thing’ is nowhere more apt than in the case of vitamins. They are essential for the healthy development and functioning of your body, but you need a small amount of each vitamin to achieve this. If you take excessively large quantities of some vitamins you may cause yourself serious harm. This is particularly true of vitamin A (an excess of which can damage the liver and cause baldness and peeling skin), vitamin D (encouraging the deposition of calcium in the tissues) and vitamin K (causing brain-damaging jaundice in young babies).
Do you need extra vitamins?
Nowadays, it is unlikely that any Westerner on a good mixed diet will suffer from lack of vitamins and the deficiency disorders that can result. On the other hand, there are conditions in which the intake of vitamins may need to be increased. For example, people suffering from malnutrition caused by faulty digestion may need extra supplies, obtained by adjusting the diet or taking commercially available vitamin pills. Others who may need additional vitamins include babies, convalescents, women who are pregnant or breastfeeding, and some elderly people.
Water-soluble and fat-soluble vitamins
There are about 14 vitamins which play particularly important roles in your body. For convenience they are often divided into two major groups. The first group is the water-soluble vitamins (C and the B complex) found mainly in fruit and vegetables. The water-soluble vitamins cannot be stored in your body, so you need small but regular supplies. If you take too much of either of these types of vitamins you are unlikely to come to any harm, because any excess will be quickly removed by the kidneys. Water-soluble vitamins can easily be leached out of foods containing them; it is best to cook fruit and vegetables for as short a time as possible in a small quantity of water in order to preserve their B and C content. The second group is the fat-soluble vitamins A, D. E and K. They are found mainly in meat and oils, which should therefore be included in any balanced diet (or taken as supplements). These vitamins can be stored in body fat, and if you take too much they can reach toxic levels. Such conditions, due to too much of a certain vitamin, are known as hypervitaminoses. The exact symptoms depend on the vitamin involved. £