Importance of Cobalt to the human system, its absorption, transportation and storage, its recommended dietary allowance, deficiency symptoms and toxicity

1. COBALT(Co)
PRESENTED BY
BIMELA CHRYSANTUS NJOBINKIR
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UNIVERSITY OF BUEA REPUBLIC OF CAMEROON
PEACE – WORK – FATHERLAND
Coordinated
By
Prof. Achidi Aduni and Dr. Tiencheu Bernard
Senior Lecturers of Biochemistry and Molecular Biology, Faculty of Science

2. Introduction
 Cobalt is a trace element, present in the body in small amounts (about 1 milligram).
 It is the active center of coenzymes called cobalamins, an essential trace dietary mineral for all animals and an
active nutrient for bacteria, algae and fungi.
 Cobalt also participates in the biotin-dependent Krebs-cycle, the process that the body uses to break down
sugars into energy.
 It is not considered essential as a separate nutrient, since it is needed above all as part of B12, which is itself
essential.
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3. Sources
 Food sources of cobalt are meat, liver, kidneys, milk, oysters, mussels, fish, shellfish. Smaller amounts of cobalt
are found in mushrooms (especially shitake). In fruits and vegetables, usually there are no cobalt This explains
why vegetarians often have a deficiency of this mineral.
 However, some small amounts of cobalt are also available in certain vegetables such as lettuce, cabbage,
spinach, figs and legumes, turnips, figs.
 Foods rich in vitamin B-12 are the only source of cobalt actively used by the body.
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5. Absorption, transport and storage
 Cobalt is unique among the essential trace elements, in that the requirement in humans is not for an ionic form
of the metal but for a preformed metallovitamin that cannot be synthesized from dietary metal.
 Meats, including the organ meats, as well as green leafy vegetables, contain and provide cobalt as a component
of vitamin B12.
 Therefore, it is the vitamin B12 content of foods and diet, rather than the ionic cobalt present, that is important
in human nutrition.
 Of the free cobalt found in these foods, very little is used although it is absorbed by the enterocytes.
 The results of tracer studies have shown that almost 100% of ingested cobalt appears in the urine. Very little
appears in the feces and very little is retained in the tissues. In small doses, the cobalt is almost completely
absorbed, while in larger doses it is poorly absorbed.
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6. Absorption, transport and storage
 The absorption of vitamin B12 (and its cobalt component) is dependent on the presence of an intrinsic factor in
the stomach. Whereas in ruminants the consumption of cobalt cures the wasting disease (pernicious anemia) it
does this not because the ruminant can absorb and then use this metal, but because the rumen flora can
synthesize vitamin B12 which in turn is absorbed.
 This then is the basis for understanding why vegetarians consuming large amounts of cobalt-rich green leafy
vegetables are at risk for developing pernicious anemia. While they obtain sufficient cobalt they can not
synthesize vitamin B12. Cobalt has no major known function aside from its central action in vitamin B12
function.
 There have been reports regarding the dependency of certain enzymes on cobalt as an activator or on the
metal’s ability to substitute for other metal ion activators.
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7. FUNCTIONS OF COBALT
 Cobalt is an integral part of vitamin B12 and therefore essential for the function of cells.
 Cobalt is also involved in the production of red blood cells and the production of antibacterial and antiviral
compounds that prevent infections.
 It also plays a key role in the metabolism of fats and carbohydrates as well as the synthesis of proteins and
conversion of folate in their active form.
 In the nervous system, cobalt is responsible for preventing demyelination, which is a condition that results in
damage to the membrane that covers the nerve fibers in the brain and spinal cord. Such prevention ensures
continuance of efficient transmission of nerve impulses.
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8. Recommended Dietary Allowance(RDA)
 Because cobalt serves no other function than as a constituent of vitamin B12. If the vitamin B12 requirement is
met, then the cobalt need is met.
 Typically, the recommended daily intake for an adult is between 5 and 8 mg of cobalt per day. If needed, cobalt
supplements are best taken in the form of vitamin B-12.
 Women who are pregnant or breastfeeding should always consult with a doctor before taking any mineral
supplements in order to prevent harm to themselves and their infants.
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9. DEFICIENCY
 A shortage of cobalt is associated with that of a deficiency in vitamin B12.
 One of the most obvious consequences is pernicious anemia, which is a disorder, characterized by symptoms such
as fatigue, weakness, numbness and tingling in the arms and legs, nausea, weight loss, confusion, and
headaches.
 Also if symptoms persist for a longer period of time, cobalt deficiency can cause neurological disorders, nerve
damage, loss of memory, mood changes and psychosis. In the worst case scenario, it can be fatal.
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10. TOXICITY
 Although cobalt is readily absorbed by the enterocyte, it is just as readily excreted by the kidney.
 Thus, toxicity in the usual sense is not a significant problem with respect to environmental exposures.
 Excess cobalt can be tolerated by a variety of species with little ill effect.
 However, cobalt does interfere with the absorption of iron and in fact can completely block iron uptake.
 Excessive cobalt intake can cause heart problems, including congestive heart failure.
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11. TOXICITY
 It can also lead to excessive production of red blood cells (polycythemia), with increased risk of blood clot
formations and stroke.
 High levels of cobalt may produce a goiter (enlargement of the thyroid gland) and reduce the overall function of
the thyroid.
 It can also cause hyperglycemia, which is a condition that involves increased blood sugar levels.
 Congestive heart failure have been observed when excess cobalt was consumed accidentally as a contaminant of
beer. Cobalt salts were once used in the production of beer as a foaming agent.
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12. REFERENCES
 Advanced nutrition and human metabolism
 Advanced nutrition micronutrients
 P. N. Ranganathan, Y. Lu, L. Jiang, C. Kim, and J. F. Collins, “Serum ceruloplasmin protein expression and
activity increases in Iron-deficient rats and is further enhanced by higher dietary copper intake,” Blood, vol.
118, no. 11, pp. 3146–3153, 2011
 . A. Hegazy, M. M. Zaher, M. A. Abd El-Hafez, A. A. Morsy, and R. A. Saleh, “Relation between anemia and blood
levels of Lead, Copper, Zinc, Iron and Cobalt among children,” BMC Research Notes, vol. 3, article 133, 2010.
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