Minerals Overview and Absorption

Minerals Overview

• Minerals are individual chemical elements that cannot be broken down further
• They are essential when dietary inadequacy causes physiological or structural abnormality.
• Dietary minerals are classified by the amount needed in the diet each day:
  • Major minerals: need 100mg or more per day
  • Trace minerals: need less than 100mg per day
  • Ultratrace minerals: trace amounts in the diet, not essential to human health
• Minerals are not energy-yielding, but they are essential for human health

Mineral Absorption and Storage

• Bioavailability of minerals is affected by age, gender, genetic variables, nutritional status, diet, prescription drugs, and fiber content of the diet.
• Most minerals are absorbed in the small intestine.
• Fiber, phytic acid, and oxalic acid can decrease mineral absorption.
• Higher fiber diets can lower the absorption of iron and zinc.
• Vitamin C intake increases iron absorption.
• Vitamin D intake increases calcium absorption.
• Excess intake of one mineral can decrease the absorption of another
  • Higher zinc intake can lower copper absorption
• Minerals are stored in various tissues, some remain in the bloodstream.
  • Calcium, phosphorus, magnesium, and fluoride are stored in bone.
  • Iron, copper, zinc, and some trace minerals are stored in the liver.
  • Other minerals are stored in muscle tissue, organs, and glands.

Mineral Toxicities

• Supplements pose the biggest risk for toxicity.
• Avoid intakes above 100% of Daily Values on supplement labels.
• Harmful interactions with other nutrients can occur.

Major Minerals

• Calcium, Phosphorus, Magnesium, Sodium, Potassium, Chloride, Sulfur.

Calcium

• Functions:
  • Bone and teeth:
    • Main structural component
    • Reservoir of calcium supply for the blood
  • In the blood/fluids:
    • Disease prevention: May protect against hypertension, high blood cholesterol, diabetes, and colon cancer.
    • Blood clotting
    • Muscle contraction (including heartbeat)
    • Nerve function
• 99% of calcium in the body is found in bones
• 1% of calcium is in fluids and cells
• Blood calcium is regulated by a complex hormone system:
  • When blood calcium is high, bone stores calcium, kidneys excrete more calcium, and intestine absorption is limited.
  • When blood calcium is low, bone releases calcium, kidney excretion decreases, and vitamin D enhances intestine absorption.
• Sources:
  • Milk and milk products:
    • Powdered fat-free milk can be added to mixed dishes to increase calcium intake.
  • Tofu, corn tortillas, some nuts/seeds, broccoli, sardines with bones.
  • Calcium-fortified soy milk, almond milk, rice milk.
• Absorption:
  • The body absorbs more calcium when needed.
    • Pregnant women absorb 50%.
    • Children/teens absorb 50-60%.
    • Adults absorb 25%.
  • Factors that enhance calcium absorption:
    • Stomach acid.
    • Vitamin D.
    • Growing stage.
    • Calcium deficiency.
  • Factors that inhibit calcium absorption:
    • Lack of stomach acid.
    • Vitamin D deficiency.
    • High phosphorus intake.
    • Anti-nutritional factors.

Bone Loss

• Osteoporosis: When calcium storage in bones is not adequate.
• In adulthood, bone mass decreases, resulting in weak bones and a risk of fractures.

Phosphorus

• The second most abundant mineral in the body.
• Functions:
  • Bone and teeth: 85% found combined with calcium for structure
  • Other functions:
    • Buffer system
    • DNA/RNA
    • Assists with energy metabolism
    • Phospholipids crucial to cell membranes
• Sources: Foods rich in protein are the best sources.
• Easily satisfy our needs.

Water

• The main constituent of the body
• Functions:
  • Carries nutrients and waste products
  • Maintains the structure of large molecules
  • Participates in metabolic reactions
  • Solvent for minerals, vitamins, amino acids, glucose and others
  • Lubricant and cushion around joints, inside the eyes, the spinal cord, and in amniotic fluid during pregnancy
  • Regulation of body temperature
  • Maintains blood volume

Water Balance

• Water balance refers to the balance between water intake and water excretion.
• It keeps the body's water content constant.
• Dehydration occurs when water intake is less than water loss
• Intoxication occurs with excessive water intake

Body Fluids and Minerals

• The movement of water is freely across cell membranes.
• The body cannot directly control water movement.
• Water follows salt; therefore, if the body controls salt movement it can also control water movement.
• Salt (sodium chloride) is a compound with positive and negative ions.
• When salt is dissolved in water, it gets separated into ions:
  • Positively charged particle = Cation
  • Negatively charged particle = Anion
• Ions carry an electrical charge, which is why they are called electrolytes.

Electrolyte Balance

• Cell membranes are selectively permeable, which means they allow the passage of some molecules but restrict the passage of others.
• Some electrolytes mostly remain outside the cell (sodium, chloride).
• Some electrolytes mostly remain inside the cell (potassium, magnesium, phosphate).
• Ion concentration controls the amount of water inside and outside the cells.
• The balance of electrolytes is crucial to regulating body fluids.