Study Notes on Micronutrient Iron by Dr. Leah Cub

Speaker: Dr. Leah Cub
Focus: Discussion on the micronutrient iron, its importance, types, physiological roles, intake guidelines, food sources, and medical nutrition therapy considerations throughout the life cycle.

Overview of Nutrient Classes
- Micronutrients are divided into two categories: major minerals and trace minerals.
Major and Trace Minerals
- Major Minerals: Required in amounts greater than 100 mg per day.
- Examples: Sodium, Chloride, Potassium, Calcium, Phosphorus, Magnesium, Sulfur.
- Trace Minerals: Required in amounts less than 100 mg per day.
- Examples: Iron, Zinc, Iodine, Selenium, Copper, Manganese, Fluoride, Chromium, Molybdenum.

Trace Mineral Significance: Iron is one of the trace minerals that will receive detailed focus in today's discussion.

Ferritin: Iron storage protein responsible for storing iron in the body.
Transferrin: Iron transport protein that carries iron in the bloodstream.
Hemoglobin: Protein in red blood cells that helps in oxygen transport.
Hematocrit: The ratio of the volume of red blood cells to the total volume of blood.
Iron Deficiency Anemia: A condition characterized by a deficiency of iron leading to decreased red blood cell production.
Erythropoiesis: The process of producing red blood cells.
Microcytic Anemia: Type of anemia involving fewer and smaller red blood cells, typically resulting from iron deficiency.

Co-factor Functions: Iron serves as a co-factor in various enzymatic reactions involved in:
- Amino acid synthesis.
- Collagen production (providing structural support to connective tissues).
- Hormone synthesis.
- Neurotransmitter synthesis (chemical messengers for nervous system functions).
Role in Oxygen Transport: Iron is integral in:
- Hemoglobin: Carries oxygen in red blood cells.
- Myoglobin: Present in muscle cells, facilitating oxygen storage.
Energy Production: Oxygen is vital in tissues for utilizing macronutrients to generate ATP (adenosine triphosphate).

RDA Definition: Established based on life cycle stages; highlights differences between genders.
Iron Needs:
- Males: 8 mg/day.
- Females: 18 mg/day (higher due to menstruation and associated blood loss).

Types of Iron in Foods: Two forms of dietary iron:
- Heme Iron:
- Found in animal-derived foods (e.g., red meat, poultry, fish).
- Higher bioavailability compared to non-heme iron.
- Non-Heme Iron:
- Present in plant and animal foods.
- Lower bioavailability; lacking in plant-based sources.

Facilitators of Non-Heme Iron Absorption:
- Vitamin C and citric acid enhance absorption.
- MFP factor (meat, fish, poultry) aids absorption of non-heme iron.
Inhibitors of Non-Heme Iron Absorption:
- Calcium, oxalic acid, tannic acid, and phytic acid.
- High oxalic acid found in certain plant foods; phytic acid in legumes and grains; soaking reduces phytic acid content.
- Foods high in tannic acid include black tea, coffee, and red wine.
Recommendations: Consume foods high in iron with vitamin C and separate from inhibitors for optimal absorption.

Stages of Iron Deficiency: Defined by the National Institutes of Health.
- Stage One: Mild deficiency/storage iron depletion.
- Decreased serum ferritin and iron levels in bone marrow.
- Stage Two: Marginal deficiency or iron deficient erythropoiesis.
- Depleted iron stores, declining transference saturation, normal hemoglobin levels.
- Stage Three: Iron Deficiency Anemia (IDA).
- Exhausted iron stores, low hematocrit and hemoglobin levels, resulting in small red blood cells (microcytic hypochromic anemia).

Life Stages with Increased Risk:
- Women in reproductive years due to menstruation.
- Pregnant women require additional iron due to increased blood volume and fetal development.
- Infants and young children need higher iron due to rapid growth, often consuming milk which limits absorption due to calcium.
Disease States and Dietary Behaviors:
- Conditions causing blood loss (e.g., ulcers, gastrointestinal infections, inflammatory bowel disease).
- Vegetarians need approximately 1.8 times more iron than omnivores because of the lower bioavailability of plant-derived iron.

General Impact on Health: Due to involvement in red blood cell production, deficiency leads to:
- Smaller, fewer red blood cells (microcytic anemia).
Symptoms of Iron Deficiency Anemia:
- Fatigue, weakness, headaches, pale appearance, poor exercise tolerance.
Behavioral Changes: Iron's role in neurotransmitter synthesis can affect mood and energy metabolism, potentially leading to apathy and lack of motivation.
Public Health Concern: Iron deficiency is a prevalent condition:
- Classified as one of the leading nutrient deficiencies globally.
- CDC estimates 38.6% prevalence among non-pregnant American females aged 12 to 21 years.

Occurrence: Generally rare, but can result from genetic disorders, repeated blood transfusions, and excessive supplemental iron intake.
Symptoms of Toxicity: Apathy, lethargy, and fatigue.
Tolerable Upper Intake Levels (UL): Established limits to prevent iron overdose.

Physiological Roles Recap: Essential in oxygen transport and synthesis of neurotransmitters, hormones, amino acids, and collagen.
Health Risks: Iron deficiency anemia is a major public health issue both nationally and globally.