Fat Soluble Vitamins and Their Functions
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Questions and Answers

What is a primary dietary source of Vitamin A from animal sources?

  • Citrus fruits
  • Carrots
  • Dairy (correct)
  • Spinach

    • Which vitamin functions as a gene regulator in the body?

  • Vitamin D
  • Vitamin A (correct)
  • Vitamin K
  • Vitamin C

    • What condition can result from Vitamin A deficiency?

  • Beriberi
  • Rickets
  • Night blindness (correct)
  • Scurvy

    • Which component is necessary for the absorption of fat-soluble vitamins?

    <p>Bile salts</p> Signup and view all the answers

    What role does retinol binding protein play in the body?

    <p>Carries Vitamin A in blood</p> Signup and view all the answers

    What can chronic excess intake of Vitamin A lead to?

    <p>Bone and liver damage</p> Signup and view all the answers

    Vitamin K2 is primarily produced by which component in the body?

    <p>Gut micro-flora</p> Signup and view all the answers

    Which of the following vitamins is NOT classified as fat-soluble?

    <p>Vitamin C</p> Signup and view all the answers

    What is the primary role of Vitamin D in the body?

    <p>Regulate calcium absorption and homeostasis</p> Signup and view all the answers

    Which condition is NOT associated with Vitamin D deficiency?

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

    What is the main dietary source of Vitamin K?

    <p>Green leafy vegetables</p> Signup and view all the answers

    What is the consequence of Vitamin E deficiency in infants?

    <p>Anaemia due to fragility of RBC membrane</p> Signup and view all the answers

    Which vitamin is known as the least toxic?

    <p>Vitamin E</p> Signup and view all the answers

    Which vitamin is synthesized by gut bacteria?

    <p>Vitamin K</p> Signup and view all the answers

    What effect does Vitamin K deficiency have on coagulation?

    <p>Coagulation defects leading to increased prothrombin time</p> Signup and view all the answers

    How much Vitamin D is recommended for the elderly?

    <p>5-15 μg/day</p> Signup and view all the answers

    What is the role of intrinsic factor in the absorption of vitamin B12?

    <p>It complexes with B12 to facilitate absorption in the lower ileum.</p> Signup and view all the answers

    Which condition is NOT a result of vitamin B12 deficiency?

    <p>Vitamin D deficiency</p> Signup and view all the answers

    What can cause a deficiency of vitamin B12 in the body?

    <p>Bacterial overgrowth in the intestines</p> Signup and view all the answers

    What is the recommended daily allowance (RDA) of vitamin B12 for adults?

    <p>1.4 – 2.4 μg/day</p> Signup and view all the answers

    What are common neurological effects associated with vitamin B12 deficiency?

    <p>Demyelination and nerve cell death</p> Signup and view all the answers

    What is the primary role of Pantothenate (B5) in the body?

    <p>Functional moiety of Coenzyme A</p> Signup and view all the answers

    What deficiency syndrome is caused by a lack of Niacin and Tryptophan?

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

    Which of the following B vitamins requires adequate intake during pregnancy to prevent neural tube defects?

    <p>B9 (Folic acid)</p> Signup and view all the answers

    What is the primary consequence of Biotin (B7) deficiency?

    <p>Skin rash and hair loss</p> Signup and view all the answers

    What is the recommended dietary allowance (RDA) for Pyridoxine (B6)?

    <p>1.3-2.0 mg/day</p> Signup and view all the answers

    What significant health issue is associated with a deficiency of Folic Acid (B9)?

    <p>Macrocytic anemia</p> Signup and view all the answers

    Which condition may result from excessive consumption of raw egg whites due to their avidin content?

    <p>Biotin deficiency</p> Signup and view all the answers

    What is the main source of Vitamin B12 (Cobalamin)?

    <p>Bacteria and yeast</p> Signup and view all the answers

    What is the primary nutritional deficiency associated with thiamine?

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

    Which co-enzyme is thiamine a crucial component of?

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

    Which food is most commonly associated with riboflavin deficiency symptoms?

    <p>Dairy products</p> Signup and view all the answers

    What is the role of niacin in metabolism?

    <p>Precursor for NAD and NADP</p> Signup and view all the answers

    What is a common symptom of wet beriberi?

    <p>Cardiovascular involvement</p> Signup and view all the answers

    What is the recommended daily allowance (RDA) of thiamine for adults consuming more than 2000 kcal?

    <p>0.9-1.2 mg/day</p> Signup and view all the answers

    Which vitamin deficiency is associated with angular stomatitis and glossitis?

    <p>Vitamin B2</p> Signup and view all the answers

    What happens to niacin when there is a low intake of tryptophan?

    <p>Synthesis of niacin decreases</p> Signup and view all the answers

    What is the main function of Vitamin C (Ascorbic acid)?

    <p>Serving as a reducing agent</p> Signup and view all the answers

    Which condition is primarily caused by a deficiency of Vitamin C?

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

    What absorption method is required for Cobalamin (Vitamin B12)?

    <p>Requires intrinsic factor</p> Signup and view all the answers

    What is the maximum capacity of Vitamin C absorption in the plasma?

    <p>250 mg/day</p> Signup and view all the answers

    Which of these sources is rich in Vitamin C?

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

    Which of the following is a dietary source of Vitamin A from plant sources?

    <p>Beta carotene</p> Signup and view all the answers

    What is the primary function of retinaldehyde in the body?

    <p>Light sensitivity in vision</p> Signup and view all the answers

    What is a primary consequence of Vitamin D deficiency in adults?

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

    Which component is required for the absorption of fat-soluble vitamins?

    <p>Bile salts</p> Signup and view all the answers

    What condition can arise from a deficiency of retinol binding protein (RBP)?

    <p>Night blindness</p> Signup and view all the answers

    What is a main function of Vitamin E in the body?

    <p>Antioxidant protection</p> Signup and view all the answers

    Which symptoms are associated with Vitamin K deficiency?

    <p>Increased prothrombin time</p> Signup and view all the answers

    Chronic excessive intake of Vitamin A can result in which of the following health issues?

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

    Which vitamin's deficiency can lead to xerophthalmia?

    <p>Vitamin A</p> Signup and view all the answers

    What dietary sources are considered good sources of Vitamin D?

    <p>Oily fish</p> Signup and view all the answers

    What is one potential effect of excessive Vitamin D intake?

    <p>Calcification of soft tissues</p> Signup and view all the answers

    What are the animal sources of Vitamin A?

    <p>Liver, dairy, and egg yolk</p> Signup and view all the answers

    How is Vitamin K primarily obtained in the body aside from dietary sources?

    <p>Gut bacteria synthesis</p> Signup and view all the answers

    Which of the following signifies the first vitamin discovered?

    <p>Vitamin A</p> Signup and view all the answers

    What condition is most commonly associated with Vitamin E deficiency?

    <p>Anaemia due to RBC fragility</p> Signup and view all the answers

    What is the recommended adequate intake of Vitamin K for adults?

    <p>60-120 µg/day</p> Signup and view all the answers

    What are the primary consequences of severe niacin deficiency?

    <p>Pellagra, characterized by the three D's: dermatitis, diarrhea, and dementia</p> Signup and view all the answers

    Which of the following vitamins is primarily sourced from bacterial production?

    <p>Vitamin B12 (Cobalamin)</p> Signup and view all the answers

    What is the role of pyridoxal phosphate in the body?

    <p>Serves as a coenzyme for enzymes involved in amino acid metabolism</p> Signup and view all the answers

    What could be a potential consequence of low folate levels during pregnancy?

    <p>Foetal neural tube defects and low birth weight</p> Signup and view all the answers

    Which of the following best describes the availability of pantothenate (B5) in the diet?

    <p>Widely available, as it can be found in almost all foods</p> Signup and view all the answers

    What is a common effect of biotin deficiency?

    <p>Dermatitis, alopecia, and glossitis</p> Signup and view all the answers

    What condition might result from a deficiency in both niacin and tryptophan?

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

    What is the recommended daily allowance (RDA) for folate during pregnancy?

    <p>300-400 μg/day, with an increase of 200-400 μg/day before conception</p> Signup and view all the answers

    What are the symptoms associated with dry beriberi?

    <p>Peripheral neuropathy</p> Signup and view all the answers

    Which of the following is a key role of niacin in the body?

    <p>Precursor for NAD and NADP</p> Signup and view all the answers

    What is the primary dietary source of riboflavin?

    <p>Milk and dairy products</p> Signup and view all the answers

    What condition is associated with thiamine deficiency due to chronic alcoholism?

    <p>Wernicke-Korsakoff Syndrome</p> Signup and view all the answers

    Which vitamin has a recommended daily allowance (RDA) of 0.9 - 1.2 mg for adults?

    <p>Vitamin B1 (Thiamine)</p> Signup and view all the answers

    Which nutrients play a crucial role in energy metabolism as part of coenzymes?

    <p>Riboflavin and Niacin</p> Signup and view all the answers

    Which of the following conditions results from riboflavin deficiency?

    <p>Angular stomatitis</p> Signup and view all the answers

    What is the main consequence of switching from brown rice to white rice in terms of thiamine?

    <p>Higher incidence of beriberi</p> Signup and view all the answers

    What is a key role of Vitamin C in the body?

    <p>Acting as a reducing agent</p> Signup and view all the answers

    Which of the following statements about Vitamin C absorption is correct?

    <p>It is absorbed by a specific transporter in the intestine.</p> Signup and view all the answers

    Which vitamin is primarily involved in the hydroxylation of proline and lysine in collagen?

    <p>Vitamin C</p> Signup and view all the answers

    What is the most common symptom associated with Vitamin C deficiency?

    <p>Sore spongy gums</p> Signup and view all the answers

    Which absorption method is utilized by Niacin (Vitamin B3) in the body?

    <p>Passive and facilitated diffusion</p> Signup and view all the answers

    What is a potential result of Vitamin A deficiency apart from night blindness?

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

    Which of the following does NOT play a role in the absorption of fat-soluble vitamins?

    <p>Presence of intestinal flora</p> Signup and view all the answers

    What is one of the functions of retinoic acid within the body?

    <p>Gene regulation</p> Signup and view all the answers

    What is a primary symptom associated with rickets in children?

    <p>Improper mineralization of bones</p> Signup and view all the answers

    Which of these foods is least likely to be a significant dietary source of Vitamin A?

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

    What is the primary consequence of Vitamin D toxicity?

    <p>Calcification of soft tissues</p> Signup and view all the answers

    What gastrointestinal function is essential for the emulsification of lipids, aiding in fat-soluble vitamin absorption?

    <p>Bile salt secretion</p> Signup and view all the answers

    Which feature is characteristic of Vitamin K's role in the body?

    <p>It is involved in blood coagulation</p> Signup and view all the answers

    Which factor most commonly contributes to Vitamin K deficiency?

    <p>Poor gut absorption</p> Signup and view all the answers

    Which condition can result from a chronic excess intake of Vitamin A?

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

    What role does retinol binding protein (RBP) serve in relation to Vitamin A?

    <p>Carries Vitamin A in the bloodstream</p> Signup and view all the answers

    What type of diet deficiency can lead to Vitamin E deficiencies in infants?

    <p>Low-fat diet</p> Signup and view all the answers

    Which of the following is NOT a source of Vitamin D?

    <p>Raw nuts</p> Signup and view all the answers

    Which vitamin is described as teratogenic when consumed in excess during pregnancy?

    <p>Vitamin A</p> Signup and view all the answers

    What common condition may arise in adults with Vitamin D deficiency?

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

    What is the adequate daily intake of Vitamin K for adults?

    <p>60-120 µg/day</p> Signup and view all the answers

    Which of the following conditions can result from a deficiency of Vitamin B12?

    <p>Megaloblastic anaemia</p> Signup and view all the answers

    What is required for the absorption of Vitamin B12 in the digestive system?

    <p>Intrinsic factor</p> Signup and view all the answers

    Which of the following is NOT a potential cause of Vitamin B12 deficiency?

    <p>Dietary deficiency in meat</p> Signup and view all the answers

    What is the role of transcobalamin II (TC II) in Vitamin B12 metabolism?

    <p>It transports Vitamin B12 in the bloodstream.</p> Signup and view all the answers

    What neurological effect is associated with a prolonged deficiency of Vitamin B12?

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

    Which statement accurately reflects the relationship between thiamine deficiency and beriberi symptoms?

    <p>Dry beriberi is characterized by cardiovascular issues.</p> Signup and view all the answers

    What role does niacin play in the body besides being a precursor for NAD?

    <p>Regulates cholesterol metabolism by reducing lipolysis.</p> Signup and view all the answers

    Which food source is most closely associated with riboflavin deficiency?

    <p>Polished rice</p> Signup and view all the answers

    What is the main consequence of insufficient thiamine intake while consuming high caloric diets?

    <p>Increased risk of Wernicke-Korsakoff Syndrome.</p> Signup and view all the answers

    What is a common deficiency symptom of riboflavin?

    <p>Angular stomatitis.</p> Signup and view all the answers

    Niacin can be synthesized from which amino acid, although this process is inefficient?

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

    Which vitamin deficiency has been linked to conditions that impact eye clarity, specifically the lens of the eye?

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

    The daily recommended allowance (RDA) for thiamine is adjusted based on what factor?

    <p>Caloric intake</p> Signup and view all the answers

    Study Notes

    Fat Soluble Vitamins

    • Fat soluble vitamins require dietary fat and bile salts for absorption.
    • Vitamins ADEK are collectively important for vision, calcium homoeostasis, antioxidant activity, and blood clotting.

    Vitamin A

    • A group of compounds (retinoids) including retinol, retinaldehyde, and retinoic acid
    • Animal sources: liver, dairy, eggs, fish oil
    • Plant sources: beta-carotene (pro-vitamin A)
    • Functions:
      • Retinaldehyde participates in vision as part of rhodopsin
      • Retinoic acid regulates gene expression
    • Carried by retinol binding protein (RBP) which is bound to transthyretin in blood
    • Deficiency:
      • Night blindness: inability to see in low light conditions
      • Xerophthalmia: dryness of the eyes, leads to corneal ulceration and blindness
      • Reproductive issues: impaired spermatogenesis and increased risk of fetal resorption
    • Deficiency can be caused by protein malnutrition due to lack of RBP.
    • Excess:
      • Teratogenic (causes birth defects)
      • Chronic ingestion of large amounts can lead to liver and bone damage, hair loss, headaches
    • RDA: 600-900 RAE/day (RAE - retinol activity equivalent), where 1 µg retinol = 12 µg β-carotene

    Vitamin D

    • Hormone-like functions: regulates calcium absorption and homoeostasis
    • Functions in immune system
    • Sources: oily fish, eggs, liver, fortified foods and sunlight
    • Synthesised in the skin under the action of sunlight, leading to potential deficiency in winter/northern latitudes
    • Deficiency:
      • Rickets: in children, failure of bone mineralization
      • Osteomalacia: in adults, demineralization of bone
    • Converted in the liver and kidney (stimulated by parathyroid hormone or PTH) to the active form called calcitriol
    • Excess:
      • Elevated plasma calcium, leading to blood vessel constriction and calcification of soft tissues
    • Adequate intake: 5-15 μg/day for elderly

    Vitamin E

    • Group of 8 tocopherols, with alpha-tocopherol being the most active
    • Functions primarily as an antioxidant in cell membranes to protect from radical damage.
    • Protects polyunsaturated fatty acids (PUFAs)
    • Deficiency:
      • Rare, but can occur in fat malabsorption syndromes
      • Premature infants (not easily transported across the placenta)
      • Haemolytic anaemia: fragility of RBC membrane
      • In experimental animals: testicular atrophy, skeletal and cardiac muscle damage, nervous system problems
    • Sources: nuts, soybeans, vegetable oil, spinach.
    • Least toxic of the vitamins: 300 mg/day has no reported ill effects

    Vitamin K

    • Cofactor for enzymes that carboxylate glutamate to γ-carboxyglutamate
    • Important for blood clotting: synthesis of prothrombin and factors II, VII, IX, X
    • Other proteins containing γ-carboxyglutamate: osteocalcin in bone
    • Sources: green leafy vegetables and gut bacteria
    • Deficiency:
      • Coagulation defects: increased prothrombin time
      • Osteoporosis: higher vitamin K intake correlates with greater bone density
      • Supplements may improve bone health, especially post-menopause
    • Deficiency usually caused by poor absorption in the gut, not dietary inadequacy

    Water Soluble Vitamins

    • Vitamins B complex and Vitamin C are water soluble, and have a variety of functions including energy metabolism, cell growth and repair, and immunity.

    Thiamine (B1)

    • Coenzyme for:
      • Pyruvate dehydrogenase: links glycolysis and Krebs cycle
      • α-ketoglutarate dehydrogenase: in Krebs cycle
      • Transketolase: in pentose phosphate pathway
    • Important for energy metabolism, NAD reduction, and glucose metabolism
    • Deficiency:
      • Beriberi: classified as 'wet' or 'dry'
        • Wet: cardiovascular disease, signs of cardiac involvement
        • Dry: peripheral and central neuropathy
      • Wernicke-Korsakoff syndrome: confusion, ataxia, paralysis of eye movement (Wernicke encephalopathy), amnesia, confabulation (Korsakoff psychosis). Common in alcoholics
    • Sources: brown rice, whole grains, legumes, nuts, seeds, meat, fish
    • Requirements: 0.5 mg/1000kcal for adults consuming more than 2000kcal; 0.8-1.0mg for low energy intake
    • RDA: 0.9 - 1.2 mg/day

    Riboflavin (B2)

    • Electron carriers in many redox reactions
    • Forms part of flavoenzymes
    • Involved in energy metabolism (NADH and FADH2 production) and glutathione reductase (important for red blood cell health)
    • Deficiency:
      • Angular stomatitis: cracks at the corners of the mouth
      • Glossitis: inflammation of the tongue
      • Dermatitis: skin inflammation
      • Conjunctivitis: inflammation of the conjunctiva (eye lining)
      • Opacity of the lens: clouding of the lens of the eye
    • Sources: milk, dairy products, eggs, meat, fish
    • RDA: 0.9 - 1.3 mg/day

    Niacin (B3)

    • Precursor for NAD and NADP, which are crucial for energy metabolism
    • Can be synthesised from tryptophan, but this process is inefficient
    • Inhibits lipolysis in adipose tissue, reducing LDL and VLDL cholesterol
    • High doses (100x RDA) are used to treat type IIb hyperlipoproteinemia
    • Sources: grains, milk, liver
    • RDA: 12-16 mg/day (7 mg/1000kcal)
    • Deficiency:
      • Pellagra: deficiency of niacin and tryptophan, characterized by 'the 3 D's': Dermatitis, Diarrhea, Dementia
      • Dermatitis is photosensitive
      • Dementia may be caused by tryptophan deficiency due to reduced serotonin synthesis
      • Maize is poor in niacin and tryptophan, contributes to pellagra

    Pantothenate (B5)

    • Forms the functional moiety of coenzyme A, essential for energy metabolism and fatty acid synthesis
    • Widespread in the diet, making deficiency very rare.
    • RDA: not established, adequate intake: 4-5 mg/day

    Pyridoxine (B6)

    • Group of molecules including pyridoxine, pyridoxamine, and pyridoxal. Essential for various metabolic pathways.
    • Pyridoxal phosphate: coenzyme for many enzymes, especially those involved in amino acid metabolism (e.g. aminotransferases)
    • Deficiency leading to clinical signs is rare.
    • Experimental animals show increased sensitivity to steroid hormones.
    • Some evidence links poor B6 intake to poor breast cancer prognosis
    • Sources: raw foods, especially those rich in protein, as heating can cause reactions with lysine
    • RDA: 1-1.7 mg/day

    Biotin (B7)

    • Coenzyme in carboxylation reactions:
      • Acetyl-CoA carboxylase: in fatty acid synthesis
      • Pyruvate carboxylase: in glucose metabolism
    • Deficiency is rare because it's widely available in the diet and synthesized by gut bacteria.
    • Deficiency Symptoms:
      • Dermatitis, hair loss, glossitis, nausea, loss of appetite
      • Raw egg white contains avidin which binds biotin tightly and can lead to deficiency when consumed in large amounts (>20 eggs/day)
    • RDA: not established but adequate intake is estimated to be 20-30mg/day

    Folate (B9)

    • Functions as 1-carbon carrier in the synthesis of amino acids, purines, and thymine
    • Important for DNA synthesis, cell division, and growth
    • Sources: fruits, vegetables, supplements
    • RDA: 300-400 μg/day
    • Increase intake to 200-400 μg/day before conception
    • Deficiency:
      • Macrocytic (megaloblastic) anaemia: abnormal development of blood cells due to purine deficiency affecting DNA synthesis
      • In pregnancy:
        • Foetal neural tube defects (spina bifida)
        • Low birth weight

    Vitamin B12 (Cobalamin)

    • Only produced by bacteria/yeast. Animals obtain it from their flora or other animals
    • Sources: liver, meat, milk, eggs
    • Absorption:
      • Requires intrinsic factor: glycoprotein produced by the stomach
      • Intrinsic factor complexes with B12 for absorption in the lower ileum
    • Large stores in the body (4-5 mg) - a few years supply
    • Coenzyme for:
      • Leucine aminopeptidase
      • Methylmalonyl-CoA mutase
      • Methionine synthase (connection to folate metabolism): involved in methyl group transfer
    • Deficiency:
      • Pernicious anaemia: megaloblastic anaemia and subacute combined degeneration of the spinal cord (neurological effects)
      • Other neurological effects: demyelination, nerve cell death, numbness, subacute combined degeneration of the spinal cord
    • Deficiency can be due to:
      • Dietary deficiency (rare, except in strict vegans)
      • Intestinal disease: impaired absorption in the lower ileum
      • Bacterial overgrowth: some bacteria require B12, overgrowth can interfere with absorption
      • Gastric malfunction: autoimmune diseases, malignancy, gastrectomy (leading to lack of intrinsic factor)
    • RDA: 1.4-2.4 μg/day

    Fat Soluble Vitamins

    • Dietary Sources
      • Vitamin A: Animal sources include liver, dairy, egg yolk, fish oils; Plant sources include beta carotene (pro-vitamin A).
      • Vitamin D: Oily fish, eggs, liver, fortified foods. Can be synthesised in the skin through sunlight exposure.
      • Vitamin E: Nuts, soy beans, vegetable oil, spinach.
      • Vitamin K: Green leafy vegetables, synthesized by gut bacteria.
    • Absorption
      • Requires normal pancreatic function, intestinal cells, and bile salts for lipid emulsification.
    • Functions
      • Vitamin A: Retinaldehyde acts as light-sensitive pigment in vision, retinoic acid is a gene regulator.
      • Vitamin D: Hormone-like functions, regulates calcium absorption and homeostasis, some immune functions.
      • Vitamin E: Antioxidant in cell membranes, limits radical damage from oxidation of polyunsaturated fatty acids.
      • Vitamin K: Cofactor for enzymes involved in carboxylation of glutamate to γ-carboxyglutamate. Necessary for formation of prothrombin and other clotting factors.
    • Deficiencies
      • Vitamin A: Night blindness, xeropthalmia, infertility, can result from protein malnutrition.
      • Vitamin D: Rickets in children, osteomalacia in adults.
      • Vitamin E: Rare, but can occur in fat malabsorption syndromes, can lead to anaemia due to fragile RBC membrane.
      • Vitamin K: Coagulation defects, osteoporosis.
    • Toxicity
      • Vitamin A: Teratogenic, chronic excessive intake can cause liver and bone damage, alopecia, headaches.
      • Vitamin D: Elevated plasma calcium, calcification of soft tissues.

    Water Soluble Vitamins

    • Dietary Sources
      • Vitamin C: Blackcurrants, guava, citrus fruits.
      • Vitamin B Complex: Found in a variety of foods, including grains, meat, poultry, fish, eggs, dairy products, legumes.
    • Absorption
      • Specific transporters in the intestines.
    • Functions
      • Vitamin C: Important in hydroxylation reactions, especially in collagen synthesis. Also involved in carnitine synthesis and iron absorption.
      • Thiamine (B1): Coenzyme for pyruvate dehydrogenase, α-ketoglutarate dehydrogenase, and transketolase. Essential for energy metabolism.
      • Riboflavin (B2): Electron carrier in redox reactions.
      • Niacin (B3): Precursor for NAD and NADP, essential for energy metabolism. Can be synthesized from tryptophan.
      • Pantothenate (B5): Functional moiety of Coenzyme A, involved in energy metabolism and fatty acid synthesis.
      • Pyridoxine (B6): Coenzyme for many enzymes involved in amino acid metabolism.
      • Biotin (B7): Coenzyme in carboxylation reactions, involved in fatty acid synthesis.
      • Folic acid (B9): 1-carbon carrier in the synthesis of amino acids, purines, and thymine.
      • Cobalamin (B12): Required for the synthesis of myelin and DNA, essential for the development of red blood cells.
    • Deficiencies
      • Vitamin C: Scurvy, characterized by sore gums, loose teeth, fragile blood vessels, anaemia, fatigue.
      • Thiamine (B1): Beriberi, can be wet or dry, characterized by cardiovascular involvement, peripheral and central neuropathies. Wernicke-Korsakoff Syndrome, a neurological disorder associated with alcoholism.
      • Riboflavin (B2): Angular stomatitis, glossitis, dermatitis, conjunctivitis and opacity of the lens.
      • Niacin (B3): Pellagra, characterized by the three D's: dermatitis, diarrhea, dementia.
      • Folate (B9): Macrocytic (megaloblastic) anaemia, neural tube defects during pregnancy.
      • Cobalamin (B12): Megaloblastic anaemia, neurological disorders.
    • Toxicity
      • Vitamin C: High doses can cause gastrointestinal upset, diarrhoea, and kidney stones.

    Fat Soluble Vitamins

    • Vitamin A
      • Functions:
        • Retinaldehyde functions as a light-sensitive pigment in vision, in Rhodopsin.
        • Retinoic acid functions as a gene regulator.
      • Deficiency can result from protein malnutrition due to a lack of RBP (Retinol Binding Protein).
      • Excess can cause teratogenicity, liver damage, bone damage, alopecia and headaches.
    • RDA: 600 - 900 RAE/day - RAE = 1 μg retinol, 12 μg β-carotene.
    • Vitamin D
      • Functions:
        • Hormone-like functions, including regulation of calcium absorption and homeostasis.
        • Some immune functions.
      • Deficiency:
        • Rickets in children, failure of bones to mineralize properly.
        • Osteomalacia in adults, demineralization of bone.
      • Sources are few and natural: oily fish, eggs, liver; Fortified foods also contribute to Vitamin D intake.
      • Converted in the liver and kidney by PTH (Parathyroid Hormone) to its active form, Calcitriol.
      • Toxicity: elevated plasma calcium can lead to contraction of blood vessels and calcification of soft tissues.
      • RDA: Adequate intake for the elderly is 5 - 15 μg/day
    • Vitamin E
      • Functions:
        • Antioxidant in cell membranes.
        • Limits radical damage from oxidation of PUFA (polyunsaturated fatty acids)
      • Deficiency is rare, may be seen in fat malabsorption syndromes.
        • Premature infants: not easily transported across the placenta.
      • Sources: nuts, soy beans, vegetable oil, spinach.
      • Least toxic vitamin, with no ill effects up to 300 mg/day.
    • Vitamin K
      • Functions:
        • Cofactor for enzymes involved in carboxylation of glutamate to γ-carboxyglutamate.
        • Necessary for formation of prothrombin, factors II, VII, IX, X.
        • γ-carboxyglutamate is also found in other proteins, e.g. osteocalcin in bone.
      • Warfarin is a vitamin K "antagonist", used as an anticoagulant.
      • Sources: green leafy vegetables. Also synthesized by gut bacteria.
      • Deficiency can cause coagulation defects, increased prothrombin time, osteoporosis, and potential heart disease.
      • Newborns should receive a single prophylactic injection of Vitamin K to compensate for a lack of gut bacteria, milk, and possible poor placental transfer.
      • Though an RDA has not been established, adequate intake is 60 - 120 μg/day.

    Water Soluble Vitamins

    • Function:
      • Thiamine (B1): Co-enzyme for pyruvate dehydrogenase, α-ketoglutarate dehydrogenase, and transketolase, all of which have important roles in energy metabolism.
      • Riboflavin (B2): Electron carriers in many redox reactions.
      • Niacin (B3): Precursor for NAD and NADP, coenzymes in redox reactions and central roles in energy metabolism.
      • Pantothenic acid (B5): Important in the formation of coenzyme A (CoA), which functions as a vital component of carbohydrate, fat, and protein metabolism.
      • Pyridoxine (B6): Involved in amino acid metabolism, synthesis of neurotransmitters and hemoglobin, and the conversion of glycogen to glucose.
      • Biotin (B7): Functions as a coenzyme in carboxylation reactions, essential for fatty acid and glucose metabolism.
      • Folic acid (B9): Essential for synthesis of DNA and RNA, cell division and growth, formation of red blood cells.
      • Cobalamin (B12): Necessary for the formation of myelin, a vital component of the central nervous system, and the metabolism of fatty acids and proteins. It also works with folate to produce red blood cells.
      • Vitamin C (Ascorbic Acid): Main function is as a reducing agent, co-enzyme in hydroxylation reactions, hydroxylation of proline and lysine in collagen, synthesis of carnitine.
    • Absorption of water soluble vitamins depends on a balance of transporter proteins, passive and active transport mechanisms.

    Deficiency Effects

    • Thiamine (B1): Deficiency can cause beriberi, characterized by wet or dry symptoms.
      • Wet: Signs of cardiac involvement.
      • Dry: Peripheral and central neuropathies.
        • Wernicke-Korsakoff Syndrome: Confusion, ataxia, paralysis of eye movement, amnesia and confabulation.
    • Riboflavin (B2): Deficiency can cause angular stomatitis, glossitis, dermatitis, conjunctivitis, and opacity of the lens.
    • Niacin (B3): Deficiency can cause Pellagra, characterised by dermatitis, dementia, diarrhea.
    • Vitamin B6 (Pyridoxine): Deficiency can cause seizures, anemia, and neurotoxicity.
    • Vitamin B12 (Cobalamin): Deficiency can cause megaloblastic anemia due to folate deficiency and neurological effects, including demyelination and nerve cell death. This can lead to numbness, muscle weakness, and subacute combined degeneration of the spinal cord.
    • Vitamin C (Ascorbic Acid): Deficiency can cause scurvy, characterized by sore spongy gums, loose teeth, fragile blood vessels, anemia, and fatigue. It can disrupt collagen synthesis as well.
    • Vitamin K: Deficiency is most often due to poor absorption in the gut rather than dietary inadequacy (e.g., Celiac disease, Crohn's disease, fat malabsorption syndromes), resulting in problems with blood clotting.

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