Mineral transport: Getting atoms to where they are needed
“Essential minerals” – what are they?
The word “minerals” means different things in different sciences. In geology, ‘minerals’ are chemical compounds that are not made by biological organisms – quartz would be an example. In biology, however, the word “mineral” refers to chemical elements, (not chemical compounds) – any element except hydrogen, carbon, nitrogen, and oxygen (which are considered too ‘organic’ to be called minerals).
An “essential mineral” is a mineral that is required by organisms for survival or at least for health. Thus, the essential minerals include the elements calcium, chlorine, chromium, cobalt, copper, iodine, iron, magnesium, manganese, molybdenum, phosphorus, potassium, selenium, silicon, sodium, sulfur, and zinc. The elements boron, nickel, tin, and vanadium are also suspected to be essential minerals. Proponents of germanium supplements claim that germanium is an essential mineral, too, but there is not yet enough evidence to include it in the list.
The essential minerals (which now we’ll just call ‘minerals’) play fundamental roles in all living organisms. Many of them are active parts of enzymes that perform chemical conversions – for example, the sugar-metabolizing enzyme Cytochrome C Oxidase contains copper and iron atoms. Other minerals are structural components of certain tissues – such as silicon, which strengthens connective tissue and nails. Still others serve as regulators and signallers – as with potassium, which is involved in controlling the activity of nerve cells.
Bioavailability of minerals
Minerals enter the body mostly as components of food. But elemental minerals (such as sulfur in the form of yellow sulfur crystals), are generally not bioavailable. To become bioavailable, mineral atoms must be combined with other elements to form chemical compounds. For example, most of the body’s sulfur comes from sulfur-containing amino acids in food proteins. Similarly, the body gets most of its manganese not from nodules of manganese metal, but from manganese-containing substances in food – that is, from plant and animal tissues in which the manganese is already incorporated into enzymes similar to those that our own bodies will make from it.
There is thus a great deal of mineral recycling going on in the biosphere: mineral compounds travel from one organism to another when the latter eats the former. But not all of the minerals found in biological organisms are the result of such recycling of mineral compounds. Some minerals enter the biological world when elemental minerals (such as manganese metal) are converted to chemical compounds (such as manganese carbonate) in the soil or elsewhere – the result both of non-biological chemical reactions and of conversions by bacteria and other microorganisms. As elemental minerals get converted to mineral compounds, these simple inorganic compounds become bioavailable to plants. The plants then perform the conversion to more complex organo-mineral compounds (such as manganese-containing enzymes) which makes them bioavailable to other organisms – to animals, for example.
Transport of minerals into cells
When mineral compounds are consumed in food, the body must somehow absorb the minerals from the digestive tract and make them available to the tissues and cells where they are needed. The process is not a simple one. The minerals cannot simply diffuse into our tissues and through cell membranes into the interior of cells – if they could, their concentrations would fluctuate in accordance with whatever amounts of minerals we happen to consume at any given time. Instead, the mineral-containing compounds (or charged mineral atoms taken from these compounds) are transported into (or out of) cells by transporter proteins – molecular devices embedded in cell membranes that recognize the minerals and allow only certain kinds to pass through the membranes. This system permits cells and tissues to regulate their internal concentrations of minerals.
Looked at from an engineer’s viewpoint, an organism’s mineral transport system serves as a regulatory device for maintaining adequate, but non-toxic, levels of mineral atoms inside cells.
The number of different kinds of transporter proteins present in a single organism is amazing. In plants, for example, there are many hundreds of different transporter types, each specialized for certain minerals, for certain tissues, and for certain conditions. Some transporters perform only “export” operations (that is, they allow certain minerals to leave the cell but not to enter it). Others are ‘importers’. Each is regulated by the conditions around it as well as by signals coming from inside or outside the cell.
Despite the large number of different transport types, a given transporter does not necessarily have the ability to specialize in a single mineral. While each transport protein seems to have a certain mineral it ‘prefers’ to transport, many of them handle additional minerals to a lesser degree. This overlap in functionality can be thought of as ‘crosstalk’ (as in a poor-quality telephone cable that allows the leakage of information between phone lines).
The system of transporter proteins and their regulation is now the focus of intense research, and rapid progress is being made in understanding it. One fact that becomes ever clearer is that the system is extremely complex. Absurdly complex, in fact – like many of the other systems found in nature.
Much of the molecular complexity in living organisms resulted not from necessity but merely from the fact that organisms develop by evolution, not by design. Evolution does not produce elegant or well-designed organisms, it produces organisms whose ancestors managed to survive even in the worst of times. Survival doesn’t require elegance – it requires adequacy, redundancy and luck. The need for redundancy gives rise to organisms that resemble Rube Goldberg machines – a mish-mash of subsystems interacting in ways that any sane designer would take to be a joke.
Consequently, the mineral transport systems we find in nature seldom break down completely, but they never work in an optimum fashion. And they do not lend themselves to simple fixes or enhancements.
The complexity of this system of natural mineral transporters is unfortunate from our standpoint. Although its multiplicity of parts with overlapping functions makes it less likely to fail completely when some of the parts are defective (as they always are), this multiplicity also makes the transport system resistant to improvement. An elegant and well-designed mineral transport system would be one with a relatively small number of different transporters, each completely specialized with respect to minerals, the direction of transport, and the range of conditions under which it operates. Such a system would be relatively easy to enhance: for example, if one wished to enhance a particular type of vanadium transport, one might develop an inhibitor for the old vanadium transporter and develop an artificial vanadium transporter with desired properties, and supply the two together to the body as a combination treatment. But the natural mineral transport system would foil such an intervention: any inhibitor we might develop for one transporter would quite likely affect other transporters as well, since there is so much overlap in their functionality. And the effects of the artificial vanadium transporter would be partially nullified by regulatory responses of the natural transporter system.
Nevertheless, attempts have been made to develop artificial transporters that override the natural ones. No attempt is made to inhibit any of the natural transporters – instead, the intention is to overwhelm them by transporting minerals into cells faster than the natural transporters can get rid of them. This approach has led to the development of several simple artificial transporters which have been used with some success for certain kinds of biological enhancement. Three such artificial transporters are: 2-aminoethylphosphonic acid (AEP), aspartic acid, and orotic acid. They are “artificial” only in the sense that in biological organisms they ordinarily play roles other than that of mineral transporters. Specifically, orotic acid is used in the biosynthesis of DNA and RNA. Aspartic acid is an amino acid that is incorporated into proteins. As for AEP, almost nothing is known about its natural role, and very little effort has been made to find out.
These three artificial transporters have become well-known in the nutritional supplement world because of the work of Hans Nieper, M.D., who studied them clinically for many years. Of the three transporters, Nieper considered orotic acid to be the most useful. He and his collaborators developed a variety of mineral derivatives of orotic acid, of which five are currently available as nutritional supplements in some countries, including Germany and the United States. These are: calcium orotate, lithium orotate, magnesium orotate, potassium orotate, and zinc orotate.
Crude tools are better than none at all
The above survey of mineral transporters should have made it clear that our current technology for enhancing the role of minerals in our bodies is still quite primitive. We have available, as mineral supplements, a few ‘artificial’ transporters that are capable of overriding the natural transporters in some situations, but which lack any regulatory features of their own. The natural transporter system, on the other hand, while overflowing with regulatory features, lacks the basic separation of functions one would find in a rationally designed system. Natural transporters evolved without any consideration of human interests or desires – basic survival was all that counted. Both sets of transporters can therefore be considered highly flawed.
Considering the fact that natural transporters at least have a track record of seeing our ancestors through some very bad times, whereas the new artificial transporters have only their brute force capabilities to their credit, is it sensible to use these crude new tools to enhance the old ones? The answer is “yes”. It makes as much sense as using any other biomedical technology of the early 21st Century – all of it is primitive, but it’s the best we have. Despite the ridiculous statements one sometimes hears – to the effect that “the human body is Nature’s masterpiece” – the fact is that, like other living organisms, the human body is a ramshackle construction that barely works even when we’re young and healthy, and fails us completely in the long run. We should therefore seek out and utilize methods for controlling or improving the way our bodies work – with appropriate caution and attention to unintended side effects. After all, we know what happens when we rely on our unenhanced bodies: our health deteriorates, we grow decrepit, and we die. Only by making use of the tools that we discover and develop will we have any chance at all of avoiding this fate.