Chapter 11- Minor Minerals (Ver 2.0)

Chapter Overview

Title: Minor or Trace Minerals

Edition: 2020

Institution: University of Hawai'i at Mānoa

Trace Minerals

Definition: Trace minerals, also known as microminerals, are essential nutrients that are required by the human body in amounts less than 100 mg daily. They play crucial roles in numerous biochemical processes and overall health.

Properties:

• Circulate freely in the blood allowing for distribution to various tissues.

• Found in a variety of foods, including both plant and animal sources, each providing unique trace minerals that contribute to dietary diversity.

• Serve as co-factors for enzymes, meaning they are essential for the proper function of many enzymes which catalyze biological reactions.

• Require minimal digestion and are primarily absorbed in the small intestine, making their bioavailability critical for nutritional adequacy.

Bioavailability of Trace Minerals

Definition: Bioavailability refers to the extent to which a mineral can be absorbed and utilized by the body.

Influencing Factors:

• The form of the food (heme iron from animal products is more bioavailable compared to non-heme iron from plants).

• Individual nutritional status and overall diet, as deficiencies in other nutrients can affect absorption.

• Age and physiological conditions such as pregnancy, where the need for certain trace minerals is increased.

Range of intake: The intake of trace minerals is typically narrow; however, a well-balanced diet can effectively meet daily requirements.

Risks of excessive intake: Consuming supplements may lead to excessive intake, posing risks that can surpass established Upper Limits for certain trace minerals, leading to toxicity.

Iron (Fe)

Description: Iron is the most abundant trace mineral in the human body, pivotal for several vital functions.

Functions:

• Facilitates oxygen transport in red blood cells via hemoglobin, which binds oxygen for delivery throughout the body.

• Supports muscle oxygen storage through myoglobin, a protein that stores oxygen in muscle tissues.

• Acts as a component of various metabolic enzymes involved in ATP (adenosine triphosphate) synthesis, crucial for energy production.

• Plays a significant role in liver metabolism and detoxification processes, aiding in the breakdown of substances.

• Essential for DNA synthesis, where it participates in the formation and function of nucleic acids.

• Most body iron is recycled from the breakdown of red blood cells, illustrating the efficiency of iron metabolism.

Structure of Hemoglobin

Components: Hemoglobin consists of peptides that form a complex structure with heme groups, each containing iron, which is vital for binding oxygen.

Iron Recycling: Iron is efficiently absorbed from the small intestine, particularly during states of low dietary intake; however, chronic blood loss can lead to continual loss of iron reserves.

Storage: Iron is primarily stored in the bone marrow, liver, spleen, and skeletal muscle, where it can be mobilized as needed.

Bioavailability of Iron

Types of Iron:

• Heme Iron: Found predominantly in animal products; it is more absorbable by the body.

• Non-Heme Iron: Found in plant foods; its absorption can be inhibited by dietary components such as phytates and tannins, which are prevalent in grains and legumes.

Absorption Influencers:

• Consuming vitamin C-rich foods (such as citrus fruits, strawberries, and bell peppers) alongside iron sources enhances non-heme iron absorption.

• Individuals following vegan diets can be at a higher risk for iron deficiency; thus, careful meal planning and incorporation of multiple iron sources is essential to meet dietary needs.

Deficiency Statistics

• Iron deficiency is a significant global health issue, with estimates suggesting that up to 80% of certain populations may be affected, particularly in developing regions due to dietary insufficiency exacerbated by infections that further hinder nutrient absorption.

Iron in the Diet

Sources of Iron:

• Heme Iron: Rich sources include red meat, poultry, and fish.

• Non-Heme Iron: Found in plant foods such as lentils, beans, spinach, and fortified cereals; can also leach from cast iron cookware during cooking.

Absorption Enhancers and Inhibitors:

• Enhancers: Consumption of meat, poultry, fish, and stomach acid can enhance non-heme iron assimilation.

• Inhibitors: Calcium, caffeine-containing beverages (like tea and coffee), bran, phytates found in whole grains, oxalates, and polyphenols can decrease iron absorption.

Iron Deficiency and Anemia

Condition: Anemia occurs when iron deficiency leads to the production of smaller red blood cells that contain decreased hemoglobin levels.

Symptoms: Common symptoms of iron deficiency anemia include fatigue, weakness, pallor, shortness of breath, and dizziness—signifying inadequate oxygen delivery to tissues.

At-Risk Groups: Particularly vulnerable populations include infants, young children, women of reproductive age, pregnant women, and athletes requiring enhanced iron intake for performance.

Toxicity of Iron

Types: Iron toxicity can be classified as acute (resulting from a single large dose) or chronic (from long-term overload due to excessive supplementation).

Sources: Conditions such as hemochromatosis, a hereditary disorder, can lead to excessive iron accumulation in the body, necessitating careful monitoring of iron intake.

Health Risks: Potential health risks associated with iron overload include fatigue, arthritis, liver damage, diabetes, organ failure, and in extreme cases, death.

Summary of Trace Minerals

Comprehensive understanding involves recommended intakes, dietary sources, primary functions, potential deficiency risks, and toxicity associated with key trace minerals such as Copper, Zinc, Selenium, and Iodine.

• Copper: Major sources include organ meats and whole grains; crucial for energy production with a recommended intake of 900 mcg/day.

• Zinc: Found in meat and dairy, plays a vital role in immune function, with recommended intake ranging between 8-11 mg/day.

• Selenium: Rich sources include meats and seafood; essential for thyroid hormone activity, with a recommended intake of 55 mcg/day.

• Iodine: Critical for thyroid hormone production, commonly found in iodized salt and seaweed, with a recommended intake of 150 mcg/day.

Important Concepts

• Contaminant Minerals: Various harmful minerals, including lead, cadmium, mercury, and arsenic, can be found in environmental sources and some foods and represent potential health risks.

• Mineral Supplements: Generally unnecessary for those with balanced diets; however, they may be essential for specific vulnerable populations such as vegans and pregnant women who may struggle to meet their needs through diet alone.

• Megadoses: Excessive intake of mineral supplements may lead to toxicity, highlighting the importance of adhering to recommended dietary allowances for optimal health.