Minerals Introduction

Major, minor and trace
Minerals are inorganic substances obtained from nutrition, found in relatively small amounts in the body, performing a variety of tasks. From the viewpoint of human physiology, minerals may be classified as major metals when they are present in the daily diet in quantities exceeding 100mg, as for example calcium, magnesium and potassium, and minor metals when the amounts are much smaller, as in the case of chromium, copper, iron and zinc. Similarly, with major non-metallics like carbon, phosphorus and sulfur, and minor non-metallics like fluorine, iodine and selenium. Both minor metals and minor non-metallics are also referred to as trace elements.

Mineral absorption
Some minerals from food or supplements are absorbed by simple diffusion across the intestinal wall and into the bloodstream. Others require a more elaborate process known as chelation, that is the formation of complexes with amino acids or proteins. In the latter case, however, some pairs of metals such as lead and iron, cadmium and zinc etc, compete for the same sites in the amino acids. The result is that excess of one mineral over its competing pair increases its chances of absorption. This explains how zinc supplements may be used to counteract the evils of cadmium absorption, and so on.

The previously named elements, more fully discussed below, may be present in our food supply in a variety of forms, such as carbonates, oxides, phosphates, silicates, sulfates, and so on, and for this reason are usually called minerals as the title of this section shows. Nutritionists commonly specify the form of an element, mainly because they know that some forms are easier absorbed than others. But there are no simple rules here. So for example, copper is almost twice as well absorbed as a carbonate than as an oxide; but the reverse is true of magnesium, which is more than twice better absorbed as an oxide than as a carbonate.

Mineral balance
Minerals are usually in a state of balance in our bodies. Excess of one may reduce the presence of others. A minor reduction may not be important. But a major reduction over a period of time may adversely affect the capacity of our bodies to form enough enzymes and electrolytes necessary for all our organic functions. The inevitable result will be one or more disorders. But knowing what each element does with regard to the others, is not easily explained or readily remembered. To take a simple example, calcium, magnesium and phosphorus have a mutually reversible relationship, that is, excess of any one of them may proportionately reduce the other two. Calcium excess can also replace zinc and manganese, but not the other way around. However, this is a simple example.

Mineral relationships may be also indirect and hence more compex. To stay with the same mineral, a calcium deficiency may cause a manganese excess. The excess of manganese may depress potassium levels, which in turn may allow excess sodium to accumulate. Thus, although there is no direct link between calcium and sodium, a calcium deficiency may indirectly cause high sodium levels and a corresponding rise in blood pressure, or hypertension. Something that would be hard to guess if one didn’t know how various minerals interact with each other.

Mineral content and losses
We get most of our minerals from plants, the grains, vegetables and fruits of our diet. But their mineral content often reflects that of their soil. As a result, vegetables show enormous variations in mineral content, frequently of the order of 800 percent, and sometimes of several orders of magnitude.

Fresh vegetables and fruits retain their mineral content. But freezing and thawing, blanching and cooking, all result in losses, although once more not in a uniform or regular manner. Taking into consideration only calcium and magnesium, thawing of asparagus results in no loss of calcium but 30 percent of magnesium. Blueberries on the other hand lose over 50 percent of magnesium but no calcium. Again cherries lose over 20 percent of calcium but no magnesium, while potatoes and spinach lose no calcium but nearly 40 and over 20 percent of magnesium respectively.

Refining of foodstuffs to produce white flour, white sugar, polished rice etc, results in even greater losses, particularly so in trace elements, which are usually found concentrated in the removed skins or husks. Here losses are often in the range of 80 percent, and not infrequently 99 percent.

In other words, there is no simple formula for taking mineral supplements. A mineral taken to ostensibly correct an imbalance, may shift the equilibrium of some other mineral systems, and in many cases produce new imbalances and new disorders. Before you take supplements, consult with an expert.