Vitamin A and D Deficiencies Quiz

Vitamins

• Vitamins are essential, non-caloric organic nutrients, required in small amounts.
• They do not supply energy.
• They cannot be synthesized by the body and must be obtained from outside sources, such as diet, rumen bacteria, and sunlight.
• Unlike carbohydrates, proteins, and fats, vitamins are individual units and are not linked together.
• They are required for growth, maintenance, reproduction, and lactation.

Learning Objectives

• Identify the meaning of vitamins.
• Compare fat-soluble vitamins with water-soluble vitamins.
• Discuss the roles, food sources, function, and consequences of deficiency and toxicity of fat-soluble vitamins.
• Discuss the roles, food sources, function, and consequences of deficiency and toxicity of water-soluble vitamins.

Classification of Vitamins

• Fat-soluble vitamins: A, D, E, and K.
• Water-soluble vitamins: C and the B complex (Thiamin, Riboflavin, Niacin, Biotin, Pantothenic acid, Vitamin B6, Folate, and Vitamin B12).

Absorption, Transport, Storage, and Excretion of Vitamins

• Fat-soluble vitamins: Absorbed into lymph and then into the blood, transported with protein carriers, and stored in the liver or fatty tissues. Not readily excreted.
• Water-soluble vitamins: Absorbed directly into the blood, travel freely in watery fluids, and are not typically stored in the body. Readily excreted in the urine.

Fat-Soluble Vitamins (A, D, E, and K)

• Vitamin A: Plays a role in vision, cell growth and division, and immune cell development. Three forms: retinol, retinal, and retinoic acid.

  • Sources: Animal foods (stored in liver), and plant-derived carotenoids (e.g., beta-carotene). The human body converts carotenoids to retinol.
  • Function: Vision (retinol), regulation of gene expression (retinoic acid), protective role against destructive oxidative reactions (vitamin E). Important for blood clotting and bone health (vitamin K).
  • Recommended Intake: For men: 900 mcg; for women: 700 mcg. Higher during lactation.

• Vitamin D: Synthesized in the body when exposed to sunlight. Essential for calcium and phosphorus utilization for healthy bones. Plays a role in muscle function and the immune system. May help prevent certain cancers, and treat heart disease, certain types of diabetes, and multiple sclerosis.

  • Sources: Sunlight, fortified milk, margarine, butter, cereals, egg yolks, liver, fatty fish.
  • Recommendation: Ages 1-70: 15 mcg/day; ages 71 and older: 20 mcg/day.
  • Toxicity: Increase in blood calcium leading to calcification of soft tissues (blood vessels, kidneys, heart, lungs, tissues around joints). Loss of appetite, nausea, vomiting, and frequent urination, fatigue, back pain.

• Vitamin E: Antioxidant, protects cells from damage. Necessary for normal nerve development, growth, and development, and wound healing. Plays a role in boosting the immune system.

  • Sources: Wheat germ oil, vegetable oils, nuts and seeds, whole grains, egg yolk, leafy green vegetables.
  • Recommendation: 15 milligrams/day for adults
  • Toxicity: Rare, but potentially problematic in high doses. Augments the effects of anti-clotting medications in high doses.

• Vitamin K: Produced by bacteria in the large intestine. Promotes blood clotting, bone formation.

  • Sources: Bacterial synthesis in large intestine, Milk, Leafy green vegetables, cabbage-type vegetables.
  • Recommendation: Men: 120 mcg/day; Women: 90 mcg/day.
  • Toxicity: None known (in doses under 1000mg).

Water-Soluble Vitamins (C and B Complex)

• Vitamin C (Ascorbic Acid): Antioxidant, helps form connective tissue, aids in wound healing, iron absorption, immune system function, and heart disease prevention.

  • Sources: Citrus fruits, cabbage-type vegetables, dark green vegetables, strawberries, and other berries, cantaloupe, melons, papayas, mangoes, potatoes, tomatoes, guava.
  • Recommendation: Men: 90 mg/day; Women: 75 mg/day; Smokers: +35 mg/day.
  • Toxicity: Nausea, abdominal cramps, diarrhea, and headache (above 1000 mg). Rashes, urinary tract problems, kidney stones.

• B-Complex Vitamins: (Thiamin, Riboflavin, Niacin, Biotin, Pantothenic acid, Vitamin B6, Folate, Vitamin B12): Critical for energy metabolism, nerve function, and a variety of other bodily functions.

  • Detailed information on specific B vitamins will follow below

Vitamin B (Individual):

• Thiamin (B1): Crucial for glucose metabolism, energy production, synthesis of neurotransmitters, necessary for RNA, DNA, and ATP synthesis.

  • Sources: Whole-grain, fortified, or enriched grain products; moderate amounts in other nutritious foods.
  • Deficiency: Beriberi (wet & dry forms). Fatigue, confusion, movement impairment, lower extremity pain, and swelling, heart failure. Wernicke-Korsakoff syndrome.

• Riboflavin (B2): Important component of flavoproteins, necessary for many metabolic pathways, including carbohydrate, lipid, and protein metabolism. Essential for growth, tissue maintenance, and cell function.

  • Sources: Milk and dairy products (yogurt, cheese), enriched or whole grains, and liver.
  • Deficiency: Cracks and redness at the corners of the mouth, sore throat, hypersensitivity to light, itching and burning eyes, dry, and scaly skin.

• Niacin (B3) / Vitamin B3: Participates in energy metabolism. Important for the proper functioning of cells.

  • Sources: Plants (especially mature grains), amino acid tryptophan which is converted into niacin in the body
  • Deficiency: Pellagra (four "Ds": Diarrhea, Dermatitis, Dementia, Death).

• Vitamin B6 (Pyridoxine): Involved in a variety of functions, including amino acid and fatty acid metabolism, conversion of tryptophan to niacin and serotonin, hemoglobin synthesis, and release of stored glucose from glycogen. Critical for nervous system development.

  • Sources: Meat, fish, poultry (protein-rich foods), starchy vegetables, and fruits, potatoes, and leafy green vegetables.
  • Deficiency: Weakness, depression, confusion, irritability, convulsions, insomnia, greasy dermatitis.

• Folate (B9) / Folic Acid: Essential for RNA and DNA synthesis, hemoglobin formation in red blood cells; Important during pregnancy for preventing neural tube defects.

  • Sources: Fortified grains, Leafy green vegetables, legumes, seeds, and liver.
  • Recommendation: 400 micrograms/day.
  • Deficiency: Anemia (large-cell type), Smooth, red tongue, mental confusion, weakness, fatigue, irritability, and headache.

• Vitamin B12 (Cobalamin): Contains cobalt, essential in order for the human body to absorb it. Used in new cell formation, maintains nerve cells, metabolizes fatty acids and amino acids, and essential for hemoglobin synthesis.

  • Sources: Animal products (meat, poultry, fish, shellfish, milk, cheese, eggs), and fortified cereals.

Test your knowledge on vitamin A and D deficiencies, particularly in children. This quiz covers symptoms, associated conditions, and recommended intakes. Perfect for students or anyone wanting to understand micronutrient deficiencies better.