Unit 11
Trace Minerals

Although present in only minute amounts in the body (less than 0.01% of body weight), trace minerals are essential for many vital functions. The essentiality of such small quantities is often difficult to determine; however, the development of highly sensitive instruments has enabled investigators to analyze food and tissue samples for extremely low concentrations, and has allowed for a clearer understanding of the role of trace minerals.

The trace minerals known to be essential for humans are iron, zinc, iodine, selenium, copper, manganese, fluorine, chromium, molybdenum, and cobalt. Others that may also be essential are arsenic, silicon, nickel, boron, tin, and vanadium. The list grows as we learn more about minerals.

Instead of providing detailed information on each trace mineral, we will look at their general characteristics, such as functions, absorption, transport, and excretion; we will also examine their dietary sources. We cover iron and zinc in greater detail than other minerals. Finally, we will discuss the need for vitamin and mineral supplements.

This unit consists of four sections:

11.1—General Characteristics of Trace Minerals
11.2—Iron
11.2—Zinc
11.3—The Need for Vitamin and Mineral Supplements

Objectives

After completing this unit you should be able to

  1. classify the general functions of trace minerals in the body.
  2. briefly describe the absorption, transport, and excretion of trace minerals, and identify their general sources for dietary intake.
  3. describe the distribution and functions of iron in the body.
  4. briefly describe how iron is absorbed, transported, stored, and recycled in the body, and explain how the body maintains iron balance.
  5. describe the symptoms of iron deficiency; distinguish between iron deficiency and iron deficiency anemia; and identify the biochemical tests used to determine iron deficiencies and anemia.
  6. describe the causes and effects of iron overload.
  7. describe the forms of dietary iron and their sources, and identify the dietary factors that enhance and inhibit iron absorption.
  8. identify the major functions of zinc in the body; describe the causes and effects of zinc deficiency and zinc toxicity; and list some major dietary and non-dietary sources of zinc.
  9. discuss the need for vitamin and mineral supplements.