Trace minerals: Iron and Copper: Videos & Practice Problems

Iron (Fe) is a vital trace mineral essential for hemoglobin and myoglobin, proteins that transport and store oxygen in the body. The recommended dietary allowance (RDA) is 8 mg for males and 18 mg for menstruating females. Copper (Cu) acts as a cofactor for enzymes, aiding in iron transport and utilization, with an RDA of 900 micrograms. Deficiencies in iron can lead to iron-deficiency anemia, characterized by fatigue and pale skin, while copper deficiency can impair hemoglobin synthesis. Foods rich in heme iron, such as meats, enhance absorption, while vitamin C can improve non-heme iron absorption from plant sources.

Iron (Fe)

Iron, denoted by the symbol Fe from its Latin name, is a crucial trace mineral that our bodies require in amounts less than 100 milligrams per day. Despite this small quantity, iron plays a vital role as a key component of hemoglobin and myoglobin, two proteins essential for oxygen transport and storage in the body. Hemoglobin, found in red blood cells, binds oxygen in the bloodstream, while myoglobin, located in muscle tissues, stores oxygen for immediate use during physical activity. The iron atom at the center of these proteins is what allows oxygen to attach and be distributed throughout the body, highlighting the importance of adequate iron intake for overall health.

The body maintains iron reserves primarily in the liver and bone marrow, which means that deficiencies do not develop rapidly if dietary intake is sufficient. The Recommended Dietary Allowance (RDA) for iron varies by gender and age: adult males aged 19 to 50 require 8 milligrams, while females in the same age group need 18 milligrams due to menstrual blood loss. The tolerable upper intake level for iron is set at 345 milligrams, with excess iron typically resulting from supplementation rather than food sources.

Iron can be obtained from two main sources: heme iron and non-heme iron. Heme iron, found in animal products such as meat, is more readily absorbed by the body compared to non-heme iron, which is present in plant-based foods. To enhance the absorption of non-heme iron, it is beneficial to consume it alongside vitamin C or heme iron sources. This is particularly important for individuals following vegetarian or vegan diets, as they may struggle to meet their iron needs without the aid of meat-based sources.

A deficiency in iron can lead to iron deficiency anemia, characterized by a reduced number of healthy red blood cells and insufficient hemoglobin production. This condition can result in symptoms such as fatigue, lightheadedness, pale skin, and weakened immunity. Certain populations, including young children and menstruating females, are at a higher risk for iron deficiency due to increased iron requirements during growth and blood loss, respectively.

Conversely, excessive iron intake, often from supplements, can lead to digestive issues such as nausea, vomiting, diarrhea, and constipation, and in severe cases, may cause organ damage. Therefore, it is crucial for menstruating females, especially those who are vegetarian or vegan, to monitor their iron intake closely to prevent anemia and maintain optimal health.

Example 1

Vegetarian females who menstruate face a heightened risk of anemia due to several interrelated factors. One primary reason is the type of iron consumed in a vegetarian diet. While many vegetables are rich in iron, they primarily contain non-heme iron, which is less efficiently absorbed by the body compared to heme iron found in animal products like meat, fish, and poultry. Heme iron is directly sourced from hemoglobin and myoglobin, making it more bioavailable. Additionally, the presence of a "meat factor" enhances the absorption of non-heme iron, a benefit that vegetarians miss out on since they do not consume these animal sources.

Furthermore, menstruation itself contributes to the risk of anemia. During menstruation, females lose blood, which necessitates a higher intake of iron to replenish the lost blood volume. If the dietary iron intake does not meet this increased demand, it can lead to a deficiency, resulting in anemia. Therefore, the combination of relying solely on non-heme iron sources and the increased iron requirements during menstruation significantly elevates the risk of anemia in vegetarian females.

Which form of iron is the most bioavailable?

• A. Heme iron.
• B. Elemental iron.
• C. Reduced iron.
• D. Non-heme iron.

Answer: (A)

If someone is following a vegan eating pattern, what can they do to help their body absorb iron?

• A. Only eat heme iron.
• B. Add meat factor to their meals.
• C. Combine foods high in vitamin C with foods high in iron.
• D. Increase soluble fiber intake.

Answer: (C)

Copper (Cu)

Copper, denoted as Cu from its Latin name, is a vital trace mineral that plays several essential roles in the body, particularly in relation to iron metabolism and overall health. As a cofactor for numerous enzymes, copper is involved in various biochemical processes, making it challenging to pinpoint a single function. However, its key contributions include facilitating iron transport, absorption, and utilization, which are crucial for maintaining healthy blood levels and preventing anemia.

In addition to its role in iron metabolism, copper is significant for energy metabolism and the synthesis of collagen and elastin, two critical structural proteins that provide strength and elasticity to tissues. Furthermore, copper helps regulate neurotransmitters, including serotonin, which is important for mood and cognitive function.

The recommended dietary allowance (RDA) for copper in adults aged 19 to 50 is 900 micrograms. To put this into perspective, there are 1,000 micrograms in a milligram, indicating that the required amount of copper is quite small compared to major minerals, which are needed in larger quantities. Foods rich in copper include organ meats, seafood, nuts, seeds, and whole grains.

However, certain factors can inhibit copper absorption. High doses of zinc, particularly from supplements, can reduce copper absorption, as can a diet high in iron, since both minerals share similar absorption pathways in the intestines. Interestingly, while vitamin C is known to enhance iron absorption, excessive amounts can also hinder copper absorption.

Although copper deficiency is rare, it can lead to impaired hemoglobin synthesis due to inadequate iron utilization, potentially resulting in anemia. On the other hand, excess copper intake is generally not a concern, as the body can manage copper levels effectively. In summary, ensuring adequate copper intake is essential, particularly due to its close relationship with iron metabolism, while the risk of deficiency or toxicity remains low.

Which of the following has NOT been shown to limit copper absorption?

• A. Zinc.
• B. Vitamin D.
• C. Iron.
• D. Vitamin C.

Answer: (B)

Which of the following are functions of copper in the body?
I) Synthesis of collagen and elastin.
II) Stabilizing the structure of certain proteins.
III) Transport of iron in the blood.

• A. I & II.
• B. I & III.
• C. II & III.
• D. I, II,& III.

Answer: (B)

Here’s what students ask on this topic:

What is the role of iron in hemoglobin and myoglobin?

Iron is a critical component of hemoglobin and myoglobin, two proteins responsible for oxygen transport and storage in the body. Hemoglobin, found in red blood cells, binds oxygen and carries it to tissues throughout the body. Myoglobin, located in muscle cells, stores oxygen for use during physical activity. The iron atom within these proteins is the binding site for oxygen, making it essential for their function. Without sufficient iron, the body cannot produce enough hemoglobin and myoglobin, leading to reduced oxygen delivery to cells and tissues, which can result in fatigue and other symptoms of iron-deficiency anemia.

What are the best dietary sources of iron?

Iron can be obtained from two main types of dietary sources: heme iron and non-heme iron. Heme iron, found in animal products such as red meat, poultry, and fish, is the most efficiently absorbed form of iron. Non-heme iron, present in plant-based foods like spinach, lentils, beans, and fortified cereals, is less readily absorbed. To enhance the absorption of non-heme iron, consuming it with vitamin C-rich foods (e.g., citrus fruits, tomatoes) or alongside meat can be beneficial. Vegetarians and vegans should pay special attention to their iron intake and consider fortified foods or supplements if necessary.

How does copper support iron transport and utilization?

Copper plays a vital role in iron transport and utilization by acting as a cofactor for enzymes involved in these processes. It helps in the absorption of iron from the intestines and its incorporation into hemoglobin, ensuring efficient oxygen transport in the blood. Copper also aids in energy metabolism and the synthesis of structural proteins like collagen and elastin. A deficiency in copper can impair iron utilization, potentially leading to anemia. While copper deficiency is rare, maintaining a balanced diet with sources like organ meats, seafood, nuts, seeds, and whole grains can ensure adequate intake.

What are the symptoms of iron-deficiency anemia?

Iron-deficiency anemia occurs when the body lacks sufficient iron to produce healthy red blood cells. Common symptoms include fatigue, pale skin, lightheadedness, and weakened immunity. These symptoms arise because insufficient iron leads to reduced hemoglobin production, impairing oxygen delivery to tissues. Individuals at higher risk include menstruating females, vegetarians, vegans, and growing children. Addressing iron-deficiency anemia involves increasing dietary iron intake through sources like meat, fortified cereals, or supplements, and enhancing absorption with vitamin C-rich foods.

What factors affect the absorption of iron and copper?

Iron absorption is influenced by its form: heme iron from animal products is absorbed more efficiently than non-heme iron from plants. Consuming non-heme iron with vitamin C or meat can enhance absorption. Copper absorption can be reduced by high doses of zinc, iron, or vitamin C, as these nutrients compete for similar pathways in the intestines. To optimize absorption, a balanced diet with varied sources of iron and copper is recommended, avoiding excessive supplementation of competing nutrients.