1.7 Micronutrients - Minerals (1)

Micronutrients - Minerals

Learning Intentions

• Identify rich sources of the following minerals and explain their functions in the body:

  • Sodium

  • Iron (haem and non-haem)

  • Calcium

  • Potassium

  • Iodine

• Explain how a deficiency in iron, calcium, and iodine can lead to health issues and why specific population groups might be at higher risk of deficiency.

• Discuss factors affecting bioavailability and absorption of minerals:

  • Haem iron vs. non-haem iron

  • Effects of caffeine and alcohol consumption.

• Describe the interrelationship of different micronutrients:

  • Vitamin C promotes the absorption of non-haem iron.

  • Calcium inhibits iron absorption.

Minerals

Definition

• Minerals are inorganic elements that must be consumed in the diet.

• They are water soluble and maintain their chemical structure until excreted.

Classification

1. Major (Macrominerals)

   • Found in the body in amounts larger than 5g

2. Trace (Microminerals)

   • Found in the body in amounts smaller than 5g

Bioavailability

• Bioavailability measures how efficiently a nutrient can be absorbed after consumption.

  • Generally low for minerals compared to vitamins.

  • Better absorbed from animal-based foods.

• Factors influencing nutrient absorption:

  • Vitamin C increases iron absorption.

  • Vitamin D is crucial for calcium absorption.

  • Inhibitors include caffeine, alcohol, and diet-related disorders (e.g., coeliac).

• Other factors: age, antioxidants, and food structure.

Sodium

Functions

• Works with potassium to regulate body fluid balance.

• Creates electrical charge for nerve impulses.

• Controls muscle contraction and relaxation.

Health Effects

• Excess sodium can increase blood volume and risk of hypertension, a cardiovascular disease risk factor.

Iron

Functions

• Vital component of haemoglobin, responsible for oxygen transport in the body.

Deficiency

• Most common nutrient deficiency globally.

• Causes reduced red blood cell production resulting in anemia, symptoms include chronic tiredness, irritability, and decreased exercise capacity.

• Populations at risk: women, vegetarians, athletes (especially in high impact sports), people with low food intake.

Forms of Iron

• Haem Iron (from animal sources): More bioavailable.

• Non-Haem Iron (from plant sources): Less bioavailable.

• Enhancers: Vitamin C-rich foods enhance absorption.

• Inhibitors: Calcium inhibits iron absorption.

Calcium

Functions

• Important for:

  • Bone and tooth formation

  • Blood clotting

  • Transmission of nerve impulses

  • Muscle contraction and relaxation

Sources

• Milk and dairy products

• Tofu, almonds, sesame seeds

• Dark leafy greens (e.g., broccoli, bok choy) and seaweed

Health Issues

• Osteoporosis: Affects over 1 million Australians, leading to fragile bones and increased fracture risk due to mineral loss exceeding replacement.

• Increased risk factors: Age, family history, low calcium and vitamin D intake, inactive lifestyle, smoking, and alcohol use.

Potassium

Functions

• Aids muscle contraction, regulates fluid and mineral balance, maintains normal blood pressure by moderating sodium effects.

Sources

• Found in leafy greens, tomatoes, eggplants, pumpkins, potatoes, carrots, beans, dairy products, meat, poultry, fish, and nuts.

Iodine

Functions

• Essential for making thyroid hormones (e.g., thyroxine) crucial for protein synthesis, enzyme activity, metabolism, and thermoregulation.

Sources

• Animal protein foods, seafood, sea vegetables, and fortified foods (e.g., iodised salt, breads, cereals, milk).

Health Risks

• Deficiency leads to hypothyroidism; excessive intake can cause hyperthyroidism.