Interactive Summaries

Chapter 13: Trace Minerals


Iron is well known as a requirement for oxygen transport. It is a component of two blood proteins that help transport oxygen in the blood. delivers oxygen through the capillary beds to the tissues. in muscle facilitates the movement of oxygen into muscle cells. Iron is essential for optimal immune function; however, iron . Iron also has a role in myelinization which influences .

The primary regulator of iron levels is absorption in the GI tract. Once iron is admitted into an intestinal cell it has three fates: it can be released into the blood and carried to other tissues by transferrin, it can be stored as ferritin, or .

There are two types of iron - heme iron and non-heme iron. Non-heme iron can be found in . Heme iron than non-heme iron. As the amount of iron ingested increases, the proportion absorbed decreases. One way to facilitate the absorption of heme iron is to make sure to include in a meal with non-heme iron. competes with iron for absorption. Deficiencies of both are common so some developing countries promote enrichment of foods with balanced amounts of both.

Transferrin delivers iron from to tissues and redistributes iron from storage sites to various body compartments. Red blood cell formation and destruction is responsible for the most iron turnover.

Depletion of iron stores is the first stage of iron deficiency. Some blood values used to detect the second stage of iron deficiency are protoporphyrin and saturation. Anemia is characterized by insufficient and/or defective blood cells. Iron deficiency anemia is also called , which also can be caused by inadequate vitamin B6 intake.


The World Health Organization has been at the forefront of a worldwide public health drive to eliminate iodine deficiency by encouraging universal salt iodization Iodine is an essential component of the two thyroid hormones triiodothyronine and thyroxine. The intestine absorbs of the iodide consumed. Seventy to eighty percent of the iodide in the body is stored in the . After salt, supply most of our dietary iodide. Severe iodine deficiency during early pregnancy may result in . Most of these children will suffer from stunted growth and are deaf, mute, and mentally retarded. Goitrogens are compounds that block the body's absorption and use of iodine. They are contained in foods such as . Goitrogens are inactivated with . Goiter is caused by . A goiter forms when the body senses a shortage of iodine and produces more and more . When T4 is converted to T3, the enzymes involved are dependent. A deficiency of this trace mineral can lead to a deficiency of iodine.


Simple dietary copper deficiency is not a significant public health concern, but excessive supplementation of other trace minerals can cause a secondary copper deficiency. Copper containing enzymes have many functions. Perhaps the most important function of copper is as a component of , which is the enzyme that catalyzes the oxidation of ferrous and ferric iron. Depending on dietary factors, the intestine usually absorbs approximately of dietary copper. A number of minerals, but most notably , may interfere with copper absorption. transports copper from the intestinal cells to the . Some of the richest food sources for copper include .

Copper defiency occurs most often in . is an extremely rare genetic copper disorder in which there is a failure to absorb copper into the bloodstream. Copper accumulates in the intestinal mucosal cells and in the muscles, spleen, and kidneys. A rare genetic disorder that results in copper toxicity is . Copper toxicity may be treated either by chelation therapy to bind and remove copper or with zinc supplementation to decrease copper absorption.

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