Download Zhang, Yajie. Cobalt. KNH 413 – Medical Nutrition Therapy II. Miami

Zhang, Yajie. Cobalt. KNH 413 – Medical Nutrition Therapy II. Miami University,
Oxford, Ohio, Spring 2013.
Cobalt
1. What is the nutrient?
Cobalt is another essential mineral needed in very small amounts in the
diet. It is an integral part of part of vitamin B12, cobalamin, which supports red
blood cell production and the formation of myelin nerve coverings. Some
authorities do not consider cobalt to be essential as a separate nutrient, since it
is needed primarily as part of B12, which is itself essential.
Cobalt, as part of vitamin B12, is not easily absorbed from the digestive
tract. The body level of cobalt normally measures 80-300 mcg. It is stored in
the red blood cells and the plasma, as well as in the liver, kidney, spleen, and
pancreas. (National Institutes of Health)
2. What is the RDA/DRI for the nutrient?
No specific RDA is suggested for cobalt. Our needs are low, and
vitamin B12 usually fulfills them. The average daily intake of cobalt is about 58 mcg. It is not usually given in supplements. (National Institutes of Health)
3. How is the nutrient metabolized?
Little evidence exists that cobalt plays a role in human nutrition other than
its being a part of vitamin B12 (cobalamin). Although ionic cobalt can
substitute for other metals in metalloenzyme activity in vitro, no evidence
exists that it acts in that capacity in vivo. In this respects, the metal 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 by
synthesized from dietary metal. Therefore, it is the vitamin B12 content of
foods and diet, rather than the ionic cobalt present, that is important in human
nutrition.
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. Cobalt, in the form of CoC2, for example, appears to regulate the
activity of certain phosphoprotein phosphatases, such as casein and phosvitin
phosphatases. In another study on phosphoprotein phosphatases, only Co2+ and
Mn2+ could reactivate enzymes inactivated by ATP, ADP, and PPi, with cobalt
being significantly the more potent reactivator. Cobalt, along with Mn2+ and
Ni2+, can also substitute for Zn2+ in the metalloenzymes, angiotensinconverting enzyme, carboxypeptidase, and carbonic anhydrase. (Advanced
Nutrition and Human Metabolism)
4. What are food sources of the nutrient?
Cobalt is available mainly as part of B12. There is some question as to
whether inorganic cobalt is actually usable in the human body. Meat, liver,
kidney, clams, oysters, and milk all contain some cobalt. Ocean fish and sea
vegetables have cobalt, but land vegetables have very little; some cobalt is
available in legumes, spinach, cabbage, lettuce, beet greens, and figs. (National
Institutes of Health)
5. What disease states alter the nutrients metabolism?
Since cobalt is available mainly as part of B12, absorption of vitamin B12
requires an intact and functioning stomach, exocrine pancreas, intrinsic factor,
liver, and small bowel. Therefore, if any of these factors is not working there is
a chance for a deficiency. Also there tend to be low levels during pregnancy.
6. What are the tests or procedures to assess the nutrient level in the body?
The plasma cobalt test is used to monitor industrial exposure to cobalt.
Cobalt poisoning through chronic exposure may result in pulmonary fibrosis,
cough, and dyspnea. Acute exposures are generally characterized by an
allergic dermatitis. Cobalt is employed industrially in certain grades of steel
and in tungsten carbide tools, and cobalt compounds are used as pigments in
paints. Although cobalt is found in the general environment, overexposure
typically occurs in the industrial environment, primarily through the
inhalation of cobalt dust and/or fumes. Cobalt exposure can also occur as a
result of ingesting medications such as cobaltous chloride. Blood is the
preferred specimen for measuring acute or recent exposure.
Serum B12 can be measured by assessing blood serum levels or by
using the Schillings test. In the Schillings test, B12 is injected and the
amount excreted in the urine is measured. Recent studies show that a more
useful indicator is to check for levels of homocysteine and methylmalonic
acid levels in the body.
(National Institutes of Health)
7. What are the drug-nutrient interactions?
Any type of drug that affects the GI function can have an effect on
the nutrient absorption. Medications that cause GI distress have the potential
to disrupt nutrient metabolism.
8. How is the nutrient measured?
The nutrient is measured in μg.
(National Institutes of Health)
9. What is the Upper Tolerable Limit?
There is not an established level for the upper tolerable limit because
toxicities are a very rare occurrence.
10. What are the physical signs of deficiency?
Deficiency of cobalt is not really a concern if we get enough vitamin B12.
Vegetarians need to be more concerned than others about getting enough cobalt
and B12. The soil is becoming deficient in cobalt, further reducing the already
low levels found in plant foods. As cobalt deficiency leads to decreased
availability of B12, there is an increase of many symptoms and problems related
to B12 deficiency, particularly pernicious anemia and nerve damage.
(Staying Healthy with Nutrition)
11. What are the physical signs of toxicity?
Toxicity can occur from excess inorganic cobalt found as a food contaminant.
Beer drinker's cardiomyopathy (enlarged heart) and congestive heart failure have
been traced to cobalt introduced into beer during manufacturing. Increased intake
may affect the thyroid or cause overproduction of red blood cells, thickened blood,
and increased activity in the bone marrow.
(Staying Healthy with Nutrition)