Mineral chelates, salts and colloids
There are several categories of what I’ll call ‘artificial mineral transporters’ – that is, substances that are employed to enhance the passage of minerals through the intestinal wall into the blood, from the blood into the tissues, or through cell membranes into cells. (See the article Mineral transport.) Among these transporters are: colloids, amino acid chelates, carbohydrate chelates, plant chelates, and organic salts. In addition, I’ll discuss a category called ‘inorganic salts’ which are neither artificial nor transporters, but are simply a form in which minerals often occur in foods. We’ll take a brief look at each of these types.
These are simple mineral compounds such as magnesium sulfate or potassium chloride. (Carbonates, such as lithium carbonate, are usually classified as inorganic salts, although it would be more logical to consider them organic.) The body is accustomed to dealing with minerals in this form, but doesn’t always do a good job of controlling absorption. Although mineral absorption increases when there is a mineral shortage, and decreases when mineral levels are high, the body’s mineral transport system often misregulates minerals that share the same transport channels. For example, when copper and zinc salts are consumed together, they compete with each other for transport into the body. An excess of zinc can therefore cause a deficiency of copper.
If one’s purpose in using mineral supplements is to force the body to use more minerals than it normally would, the inorganic salts would be a poor choice.
Colloids are materials made up of solid particles of such small size that when dispersed in water they remain in suspension rather than sinking. “Colloidal mineral” supplements consist of mineral salts or other mineral compounds converted into colloidal form, either by grinding or by rapid crystallization.
Most colloidal substances are poorly bioavailable, since the colloidal particles, small as they are, are nevertheless far too large to be intestinally absorbed whole, and nearly all of the active ingredients are trapped in the interior of the particles, where they cannot come into contact with the transport channels in the cells of the gut. However, if a colloidal substance can dissolve into the coating of the gut, it would then release all of its mineral material for potential absorption. At this point, the material would no longer be a colloid and its absorption characteristics would become those of its components – i.e., inorganic salts, chelates, or whatever.
The word ‘chelator’ refers to a substance consisting of molecules that bind tightly to metal atoms, thus forcing the metal atoms to go wherever the chelator goes. The bound pair – chelator plus metal atom – is called a ‘chelate’. Chelators of nutritional interest include amino acids, organic acids, proteins, and occasionally more complicated chemicals found in plants.
One particular chelator that we specifically want to exclude from this discussion is EDTA (EthyleneDiamineTetraacetic Acid), which is used in a controversial treatment called “Chelation Therapy”. It involves injections of EDTA into the blood to remove (often imaginary) metallic “toxins”.
We are interested here in chelators that are intended to carry mineral atoms into the body, or into the cells themselves, in larger amounts than the body would normally allow. It is proposed that the chelators are treated as desirable molecules by the recognition systems in cell walls, and are therefore given entry into the cells, along with their baggage of mineral-atoms. When this process occurs in the cells lining the digestive tract, the minerals gain entry to the bloodstream; when it occurs in the cells lining the blood vessels, the minerals gain entry to other body tissues.
Amino acid chelates
Amino acids have three basic parts: the amino ‘group’ (i.e., group of atoms), the acid group, and the R-group. It is the R-group that determines the name and specific character of an amino acid – determining, for example, whether the amino acid is aspartic acid or lysine or tryptophan.
Amino acids can act as chelators when they react with positively charged metal atoms, forming a strong chemical bond. The metal atoms of interest here are those that serve as dietary minerals. (These are listed in the article List of dietary minerals.) To take a specific example, a chelate can be formed between the amino acid arginine (the chelator) and zinc (the mineral).
Certain combinations of minerals and amino acids do not form good chelates because the chemical bonding is too weak. For example, if you try to use the amino acid glutamic acid as chelator and sodium as the mineral, you can get monosodium glutamate, which is considered to be merely an “organic salt”, not a chelate. Monosodium glutamate undoubtedly exhibits some small degree of chelation, but this is outweighed by its character as a salt. Generally speaking, sodium and potassium form poor chelates.
Many minerals form good chelates with amino acids. Some, like lead and cadmium, have no known function in the body and are considered purely toxic. Others can be toxic in high concentrations, but are required by the body in lesser amounts. The latter include: boron, calcium, chromium, cobalt, copper, iron, magnesium, manganese, molybdenum, nickel, tin, vanadium, and zinc.
The argument in favor of using amino-acid-chelated minerals goes like this:
The body is very efficient at absorbing amino acids. Dipeptides (two amino acids linked together via the amino group of one amino acid and the acid group of the other) are especially well absorbed thanks to a dedicated transport system found in cells of the intestinal wall. When mineral atoms are strongly bonded (i.e., chelated) to dipeptides they get dragged by the dipeptides across the intestinal lining and into the body.
Furthermore, amino-acid chelation bypasses the competitive interactions that can occur between different minerals when they are absorbed as salts. (See the “Inorganic salts” section above.) Use of chelated minerals avoids this problem since they are transported by different mechanisms.
How valid is this argument? It’s hard to say, since very little published, impartial research has been done. Albion Laboratories, Inc. – the leading producer of amino-acid chelates – has sponsored many studies of its products, but these cannot be considered impartial. However, the case for amino-acid chelators of iron is a good one and is supported by a number of independent studies. The situation is less clear for other minerals. On the other hand, Albion’s products are widely used for animal and plant nutrition, and that says a lot for these substances, since farmers tend to be pragmatic and are not easily fooled about the health of their crops and animals. It seems likely, therefore, that amino-acid chelates can effectively override the normal mineral regulatory mechanisms both in plants and animals, including humans. (Albion, incidentally, has an excellent collection of research newsletters that focus on medical, veterinary and agricultural usage of minerals.)
This category of chelates is based on a large number of chelators which are called ‘organic acids’. A partial list of the organic acid chelators of interest in nutrition would include: gluconate, lactate, citrate, erythorbate, oxalate, saccharate, succinate, fumarate, 2-aminoethylphosphonate (AEP), picolinate, and orotate. (Grammatical note: chemical names ending in ‘-ate’ can equally well be expressed as ‘-ic acid salt’. For example, ‘zinc lactate’ is the same thing as ‘lactic acid salt of zinc’ or ‘zinc salt of lactic acid’.)
These chelators are called ‘organic acids’ because they are substances found in living organisms and they contain carbon atoms. The bond that forms between organic acids and mineral atoms is a relatively weak one, and is called a ‘salt bond’ or ‘electrostatic bond’. This means that the mineral atom can easily be pulled from the chelator by another molecule (such as a water molecule), or they can be separated by random jostling. Since the purpose of mineral chelation is to cause the mineral atoms to accompany the chelators through cell membranes (i.e., through the walls of the intestines, blood vessels, or other tissues), the organic acids perform only moderately well as chelators.
Gluconate is the most widely used of the organic acid chelators, and has a decades-long record of effectiveness and safety. It is frequently used to correct mineral deficiencies, to treat inflammatory acne, to regulate CD8 T-cells, and for anorexia. Zinc gluconate can also suppress hepatitis symptoms in dogs. There is, however, no reason to think that the gluconate is a highly efficient chelator.
A number of minerals are available as picolinate supplements: boron, chromium, copper, magnesium, manganese, molybdenum, selenium, vanadium, and zinc. Chromium picolinate is widely used to enhance athletic performance, and has been well studied. Vanadyl picolinate shows great promise as a glucose regulator in diabetes. The other picolinates have received very little attention from researchers. It is known that the bioavailability of zinc, copper and magnesium increases significantly when it is combined with picolinic acid in the diet, and that zinc picolinate is superior as a chelate to zinc gluconate and zinc citrate. This scanty information suggests that the picolinates are relatively effective chelators and mineral transporters.
We have a bit more information about the orotates. Magnesium orotate showed good results in studies of athletic performance, both in healthy men and cardiac patients; it improves blood lipid profiles and inhibits arterial plaque formation. Lithium orotate (a freely available nutritional supplement), is at least as good a source of lithium as lithium carbonate (a prescription drug) which is used for treating mental conditions such as manic-depression (bipolar disorder), autism, obsessive-compulsive disorder. Lithium carbonate has also shown benefit in treating the effects of alcoholism. The other orotates have received little research attention except from their developer, Hans Nieper, whose scientific methods left a lot to be desired. The orotates do, however, have a many users and a correspondingly large amount of anecdotal information. For example, calcium orotate is regarded as a good appetite suppressant and cognitive stimulator.
Comparison of chelators
A few researchers have tried to answer the question of which types of chelators produce the highest bioavailabilities of minerals. Theirs were veterinary studies and, unfortunately, they used animals that had first been rendered mineral-deficient by being fed special mineral-deficient diets. This method does not provide information about relative bioavailabilities for the condition we are interested in here, namely: the condition of being a non-mineral-deficient human. We are interested in increasing our intracellular mineral concentrations beyond the levels allowed by ordinary nutrition and by the body’s normal regulatory processes. (See the article Mineral transport.)
The general impression one gets from looking at the published research on this subject is that inorganic salts are adequate mineral sources for correcting dietary mineral deficiencies in healthy people, but that more specialized sources are needed for correcting deficiencies due to disease, or for by-passing the body’s mineral regulators in order to achieve higher-than-normal mineral levels. For these purposes organic salts appear to be better than inorganic salts, and amino-acid chelates appear to be better than the organic salts. Among the organic salts, the picolinates and orotates appear to offer advantages over other available forms.
Future research may paint a rather different picture of the relative values of different mineral transporters than the one painted here. For example, the apparent superiority of the picolinates and orotates is based on indirect evidence, since there is hardly any published research directly comparing the efficacy of these forms with other mineral forms. The orotates remain largely neglected by researchers, and so have the picolinates – with the one exception of Chromium Picolinate. The relative value of different chelators and other transporters may turn out to depend strongly on which mineral one is dealing with, and upon various other factors. For now, our decisions about which mineral supplements to use will have to be guided by the smattering of knowledge available and by our own willingness to experiment with them.