Marine animals contain cobalt at 0.5 to5.0 ppm; land animals 0.03 ppm with greatest concentrations in the bone and liver.

Essential for blue green algae, some bacteria and fungi, some plants, insects, birds, reptiles, amphibians and mammals including man. Cobalt functions as a cofactor and activator for enzymes, fixes nitrogen during amino acid production; a single cobalt atom is the central metal component of vitamin B₁₂ which itself is a co-factor and activator (cobamide coenzymes) for several essential enzymes.

B₁₂/Cobalt is chelated in a large terapyrrole ring similar to the phorphyrin ring found in hemoglobin and chlorophyll. The original B₁₂ molecule isolated in the laboratory contained a cyanide group, thus the name cyanocobalamin; there are several different cobalamine compounds that have vitamin B₁₂, activity, with cyanocobalamin and hydroxycobalamin the most active.

Vitamin B₁₂ is a red crystalline substance that is water-soluble; the red color is due to the cobalt in the molecule. Vitamin B₁₂ is slowly deactivated by acid, alkali, light and oxidizing or reducing substances; about 30 percent of B₁₂ activity is lost during cooking (electric, gas or microwave).

In 1948, B₁₂ was isolated from liver extract and demonstrated anti pernicious anemia activity.

The essentiality of cobalt is unusual in that the requirement is for a cobalt complex known as cyanocobalamin or vitamin B₁₂. A pure cobalt requirement is only found in some bacteria and algae and the need for B₁₂/cobalt is thought by some to represent a symbiotic relationship between microbes which generate and manufacture B₁₂ from elemental cobalt and vertebrates that require B₁₂.

Ruminants (i.e.-cows, sheep, goats, deer, antelopes, giraffe, etc.) can use elemental cobalt, however, the microbes fermenting and digesting plant material in their first stomach (rumen) convert elemental cobalt into vitamin B₁₂ which the animal can use.

Carnivores can get their B₁₂ from the ruminant by consuming stomach contents, liver, bone and muscle from their kills.

Poultry, lagomorphs (rabbits and hares), and rodents actively eat feces during the night (coprophagy) and in the process obtain B₁₂ manufactured by intestinal microorganisms.

Metallic cobalt is absorbed at the rate of 20 to 26.2 percent in mice and humans if intrinsic factor is present in the stomach and the stomach pH is 2.0 or less. Intrinsic factor is a mucoprotein enzyme known as Castle's intrinsic factor and is part of normal stomach secretions.

If a person has hypochlorhydria (low stomach acid - usually a NaCl deficiency) the intrinsic factor will not work and B₁₂/cobalt is not absorbed - this is why doctors frequently give B₁₂ shots to older people on salt restricted diets. Sublingual (under the tongue) and oral spray B₁₂ is available; plant derived cobalt is very bioavailable, however, because of low salt diets and cobalt depleted soils, vegetarians frequently have B₁₂ deficiencies.

The B₁₂ intrinsic factor complex is primarily absorbed in the terminal small intestine or ileum; calcium is required for the B₁₂ to cross from the intestine into the bloodstream as well as an active participation by intestinal cells. Simple diffusion can account for one to three percent of the vitamin’s absorption.

There is an enterohepatic (Intestine direct to the liver) circulation of B₁₂ that recycles B₁₂ from bile and other intestinal secretions which explains why B₁₂ deficiency in vegans may not appear for five to ten years.

The maximum storage level of B₁₂ is 2 mg, which is slowly released to the bone marrow as needed. Excess intake of B₁₂ is shed in the urine i.e. contributing the notion of "expensive urine".

Vitamin B₁₂/Cobalt joins with folic acid, choline and the amino acid methionine to transfer single carbon groups (methyl groups) in the synthesis of the raw materials to make RNA and the synthesis of DNA from RNA (directly involved in gene function - remember preconception nutrition to prevent birth defects!). Growth, myelin formation (converts cholesterol to the insulating material myelin found around nerves in the brain and large nerve trunks) and RBC synthesis are dependant on B₁₂.

The discovery of the essentiality of cobalt came from observing a fatal disease ("bush sickness") in cattle and sheep from Australia and New Zealand; it was observed that "bush sickness" could be successfully treated and prevented by cobalt supplements.

Bush sickness was characterized by emaciation (unsupplemented vegans), dull stare, listless, starved look, pale mucus membranes, anorexia (loss of appetite), anemia microcytic/hypochromic) and general unthriftiness.

In humans, a failure to absorb B₁₂/Cobalt results in deficiency disease. This can result from a surgical removal of parts of the stomach (eliminates areas of intrinsic factor production), or surgical removal of the ileum portion of the small bowel, small intestinal diverticula, parasites (tapeworm), celiac disease (allergies to wheat gluten and cows milk albumen) and other malabsorption diseases. Pernicious anemia and demyelination of the spinal cord and large nerve trunks are classic for B₁₂/Cobalt deficiency.

Less than 0.07 ppm cobalt in the soil results in cobalt deficiency in animals and people who eat crops grown from those soils; 0.11 ppm cobalt in the soil prevents and cures Cobalt deficiency.

The RDA for B₁₂/Cobalt is 3 to 4 mcg per day. We prefer expensive urine and like 250 to 400 mcg per day, especially while preparing for pregnancy and nursing (remember a baby being nursed by a deficient mother has their deficiency extended over a long period of time and may result in serious permanent nerve damage).

Cobalt excess in man (20 to 30 mg/day) may create erythropoiesis (increase in RBC production) with increased production of the hormone erythropoieten from the kidney. Cobalt is also a necessary co-factor for the production of thyroid hormone.

Cobalt is a trace mineral nutrient for bacteria. Its only established role in animals is as a component of vitamin B₁₂. Animals like ruminants (cows) that depend on bacteria for vitamin B₁₂ require inorganic cobalt as a nutrient. Only microorganisms are capable of incorporating cobalt into vitamin B₁₂.

The body cannot use unattached cobalt and cobalt supplements are therefore ineffective. Though cobalt has a low order of toxicity, overdosing with cobalt could lead to goiter and over-production of red blood cells in susceptible individuals.

Low concentrations of cobalt salts were once added to beer as an antifoaming agent. However, cobalt was incriminated in several epidemics of cardiac failure among beer drinkers. The typical American diet provides low levels of cobalt. Green leafy vegetables are the richest source, while dairy products and refined grain products are among the lowest. For example, spinach provides 0.4 to 0.6 mcg per gram, and white flour contains 0.003 mcg per gram. The oral intake of cobalt necessary to produce toxicity is many times greater than can be obtained by normal consumption of foods and beverages.

Cobalt Physiology

The only known function of Co is its participation in metabolism as a component of vitamin B₁₂; thus the signs of Co deficiency are in reality signs of a shortage of the vitamin. Vitamin B₁₂ is an essential part of several enzyme systems that perform very basic metabolic functions. Most of the cobalamins occur as two coenzymatically active forms, adenosylcobalarnin and methylcobalamin. Cyanocobalamin is converted within cells to methylcobalamin, a coenzyme for methyltransferase, or adenosylcobalamin, the coenzyme for mutase.

Most reactions of vitamin B₁₂ enzymes involve transfer or synthesis of one-carbon units, for instance, methyl groups. Though the most important tasks of vitamin B₁₂ concern metabolism of nucleic acids and proteins, it also functions in (1) purine and pyrimidine synthesis; (2) transfer of methyl groups; (3) formation of proteins from amino acids; and (4) carbohydrate and fat metabolism (McDowell, 1989). Vitamin B₁₂ promotes red blood cell synthesis and maintains nervous system integrity, which are functions noticeably affected in a deficiency.

Vitamin B₁₂ is metabolically related to other essential nutrients, such as choline, methionine, and folacin, and functions in transmethylation and biosynthesis of labile methyl groups (McDowell, 1989). The purine bases (adenine and guanine) as well as thymine are constituents of nucleic acids; with a folacin deficiency, there is a reduction in biosynthesis of nucleic acids essential for cell formation and function. Deficiency of B₁₂ induces a folacin deficiency by blocking utilization of folacin derivatives. A vitamin B₁₂-containing enzyme removes the methyl group from methylfolate, thereby regenerating tetrahydrofolate (THF), from which is made the 5,20-methylene THF required for thymidylate synthesis.

Metabolism of labile methyl groups plays a significant part in biosynthesis of methionine from homocysteine. A vitamin B₁₂-requiring enzyme, 5-methyltetrahydrofolate-homocysteine methyltransferase, catalyses reformation of methionine from homocysteine. Activity of this enzyme is depressed in liver of vitamin B₁₂-deficient sheep (MacPherson, 1982). This defect could lead to a deficiency of available methionine, which may account for impairment of nitrogen metabolism in vitamin B₁₂-deficient sheep.

Overall synthesis of protein is impaired in vitamin B₁₂-deficient animals. Wagle et al. (1958) demonstrated that rats and baby pigs deprived of vitamin B₁₂ were less able to incorporate serine, methionine, phenylalanine, and glucose into liver proteins. Impairment of protein synthesis may be the principal reason for the growth depression frequently observed in these animals (Friesecke, 1980).

In animal metabolism, propionate of dietary or metabolic origin is converted into succinate, which then enters the tricarboxylic acid (Krebs) cycle. Propionate is a three-carbon, and succinate, a four-carbon compound; therefore, this process requires the introduction of a one-carbon unit. Methylmalonyl CoA isomerase (mutase) is a vitamin B₁₂-requiring enzyme (5' deoxyadenosyl cobalamin), which catalyzes the conversion of methylmalonyl-CoA to succinyl-CoA.

Metabolism of propionic acid is of special interest in ruminant nutrition because of the large quantities produced during carbohydrate fermentation in the rumen. The main source of energy to ruminants is not glucose but primarily acetic and propionic acids. In Co or vitamin B-deficiency, the rate of propionate clearance from blood is depressed, and methylmalonyl-CoA accumulates. This results in an increased urinary excretion of methylmalonic acid and also loss of appetite because impaired propionate metabolism leads to higher blood propionate levels inversely correlated to voluntary feed intake (MacPherson, 1982).