Mineral Absorption and Bioavailability
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Questions and Answers

What is a potential consequence of excessive phosphorus intake?

  • Bone gain
  • Magnesium toxicity
  • Bone loss (correct)
  • Increased calcium levels
  • What is the primary function of magnesium in the body?

  • To regulate blood pressure
  • To regulate body temperature
  • To act as an enzyme cofactor (correct)
  • To store energy in the muscles
  • What is a characteristic of magnesium deficiency?

  • It is very common in adults
  • It only affects the bones
  • It always leads to toxicity
  • It is rare in healthy individuals (correct)
  • What is the primary function of sodium in the body?

    <p>To regulate plasma volume and body water content</p> Signup and view all the answers

    What is a common source of sodium in the diet?

    <p>Table salt</p> Signup and view all the answers

    What is a potential consequence of sodium deficiency?

    <p>Fatigue</p> Signup and view all the answers

    What is a characteristic of phosphorus toxicity?

    <p>It stimulates secondary hyperparathyroidism</p> Signup and view all the answers

    What is a characteristic of magnesium toxicity?

    <p>It causes depressed deep tendon reflexes</p> Signup and view all the answers

    What affects the absorption of minerals?

    <p>Other nutrients and compounds in the diet</p> Signup and view all the answers

    What is the effect of excess iron on zinc absorption?

    <p>It reduces zinc absorption</p> Signup and view all the answers

    What is the role of selenium, manganese, and zinc in the body?

    <p>They form part of the body's defenses against free-radicals</p> Signup and view all the answers

    What is the concern with excess intake of minerals?

    <p>It may cause mineral imbalances or have other side-effects</p> Signup and view all the answers

    What is the classification of calcium, phosphorus, and magnesium?

    <p>Macrominerals</p> Signup and view all the answers

    Why are patients with biliary stones advised not to eat tomatoes?

    <p>Because tomatoes are high in oxalate</p> Signup and view all the answers

    What is the effect of malabsorption of lipids on calcium absorption?

    <p>It reduces calcium absorption</p> Signup and view all the answers

    What is the common problem often affecting women and young children throughout the world?

    <p>Iron deficiency anaemia</p> Signup and view all the answers

    What is a risk factor for heart disease and stroke associated with excessive sodium intake in the diet?

    <p>Raised blood pressure</p> Signup and view all the answers

    What is the main function of potassium in the body?

    <p>Maintenance of water and electrolyte balance</p> Signup and view all the answers

    Which of the following foods is a rich source of potassium?

    <p>Dried fruits</p> Signup and view all the answers

    What is a potential consequence of potassium deficiency?

    <p>Muscular weakness</p> Signup and view all the answers

    What is the main function of chloride in the body?

    <p>Formation of gastric fluid</p> Signup and view all the answers

    What is the role of the chloride-bicarbonate exchanger in the body?

    <p>Increases the permeability of the erythrocyte membrane to HCO3-</p> Signup and view all the answers

    What is the role of chloride in CO2 transport to the lungs?

    <p>Facilitating the transport of CO2 from tissues to the lungs</p> Signup and view all the answers

    What is a potential consequence of excessive potassium intake?

    <p>Cardiac arrest</p> Signup and view all the answers

    What is the primary function of calcium in the body?

    <p>To form bones and teeth</p> Signup and view all the answers

    What is the normal range of serum calcium levels?

    <p>8.5-10.5 mg/dL</p> Signup and view all the answers

    What is the role of parathyroid hormone in calcium regulation?

    <p>It increases calcium levels in the blood</p> Signup and view all the answers

    What is the consequence of long-term dietary calcium insufficiency?

    <p>Net loss of calcium from bones</p> Signup and view all the answers

    What is the condition caused by vitamin D deficiency in adults?

    <p>Osteomalacia</p> Signup and view all the answers

    What is the role of calcium-binding proteins in calcium absorption?

    <p>They increase calcium absorption</p> Signup and view all the answers

    Why is adequate calcium intake important during lactation?

    <p>It supports the growth of the infant</p> Signup and view all the answers

    What is the term for minerals required in smaller quantities (less than 100 mg/day)?

    <p>Microminerals</p> Signup and view all the answers

    What happens to HCO3- in the lungs?

    <p>It is converted to CO2 and exhaled</p> Signup and view all the answers

    What is the role of the chloride-bicarbonate exchanger?

    <p>To facilitate the movement of HCO3 across the erythrocyte membrane</p> Signup and view all the answers

    What is the result of a chloride deficiency?

    <p>Hypochloremic alkalosis</p> Signup and view all the answers

    What is sulfur a part of?

    <p>Many proteins and sulfolipids</p> Signup and view all the answers

    What is a major source of sulfur in the diet?

    <p>Protein sources containing sulfur amino acids</p> Signup and view all the answers

    What is a function of sulfur in the body?

    <p>Part of many proteins and coenzymes</p> Signup and view all the answers

    What is the function of the chloride-bicarbonate exchanger in the erythrocyte?

    <p>To facilitate the movement of HCO3 across the erythrocyte membrane</p> Signup and view all the answers

    What is the consequence of a lack of chloride in the transport of HCO3?

    <p>HCO3 transport stops</p> Signup and view all the answers

    Study Notes

    Factors Affecting Mineral Bioavailability and Absorption

    • Absorption of minerals is influenced by various factors, including other nutrients and compounds in the diet.
    • Oxalate and phytate, found in some foods, chelate divalent cations, reducing the absorption of minerals like calcium, iron, and zinc.
    • Phytate is commonly found in cereals, especially wheat, while oxalate is found in vegetables, particularly tomatoes.
    • Patients with biliary stones (calcium oxalate) are advised to avoid eating tomatoes.
    • Malabsorption of lipids can lead to malabsorption of calcium (Ca-palmitate, Ca-stearate).

    Mineral Interactions and Deficiencies

    • Excess intake of one mineral can block the absorption of another, e.g., excess iron reduces zinc absorption.
    • Vitamin C increases iron absorption when consumed during the same meal.
    • Iron deficiency anemia is a common problem, particularly affecting women and young children worldwide.
    • Deficiencies of other minerals are rare in Western societies, but excess intakes can be a concern (e.g., sodium).
    • Selenium, manganese, and zinc may help protect against free radicals and diseases like cancer and heart disease.

    Classification of Minerals

    • Minerals are classified into macrominerals (needed in larger amounts, >100mg/d) and microminerals (needed in smaller amounts, <100mg/d).
    • Macrominerals include calcium, phosphorus, magnesium, sodium, potassium, and chloride.
    • Microminerals, also known as trace minerals, include iron, zinc, iodine, fluoride, selenium, and copper.

    Calcium (Ca)

    • Calcium is the most abundant mineral in the body, with most of it found in bones.
    • Calcium plays a crucial role in essential processes, including nerve and muscle function, blood clotting, and intracellular signaling.
    • Calcium absorption requires calcium-binding protein, and its level in the blood is regulated by parathyroid hormone and vitamin D.
    • Low calcium intake can lead to osteomalacia (softening of bones) and rickets in children.

    Phosphorus (P)

    • Phosphorus is essential for bone and tooth structure, energy metabolism, and electrolyte balance.
    • Phosphorus deficiency is rare, but an excessive intake can lead to calcium being pulled from bones, causing bone loss.

    Magnesium (Mg)

    • Magnesium is present in all tissues, including bone, and is required for enzyme cofactors, bone and tooth structure, and normal energy metabolism.
    • Magnesium deficiency can lead to muscle weakness, electrolyte imbalance, and bone loss.

    Sodium (Na)

    • Sodium is the principal cation in extracellular fluid and helps regulate plasma volume, electrolyte balance, nerve function, and energy utilization.
    • Excessive sodium intake is associated with an increased risk of hypertension and heart disease.

    Potassium (K)

    • Potassium is the principal cation in intracellular fluid and is essential for water and electrolyte balance, nerve function, and cell signaling.
    • Potassium has a beneficial blood pressure-lowering effect in people with hypertension.
    • Potassium deficiency can lead to muscular weakness, mental confusion, and paralysis.

    Chloride (Cl)

    • Chloride is an anion closely connected with sodium in food, body tissues, and body fluids.
    • Chloride is essential for the formation of gastric fluid, fluid and electrolyte balance, and acid-base balance.
    • Chloride is involved in CO2 transport to the lungs from tissues and is essential for the chloride-bicarbonate exchanger system.

    Sulfur

    • Sulfur is part of many proteins, sulfolipids, conjugated bile acids, and coenzyme A.
    • Sulfur is also present in thiamine, biotin, and insulin.
    • Most sulfur in the diet comes from protein sources containing sulfur amino acids like cysteine, cystine, and methionine.

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    Description

    This quiz explores the factors that affect the absorption and bioavailability of minerals, including the impact of oxalate and phytate on calcium, iron, and zinc absorption.

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