Nutrition and Vitamins Quiz

Vitamins

• Vitamins are organic compounds crucial for health and growth.
• They are not synthesized in the human body, so they must be consumed through diet.
• Deficiency in vitamins can lead to various diseases.
• Vitamins do not become part of tissues and are not oxidized by tissues.
• Vitamins are needed in small amounts.

Overview of Vitamins

• Understanding the difference between vitamins and coenzymes is important.
• Knowing the pathologies associated with water-soluble vitamins is essential.
• Defining vitamins and classifying them according to solubility is key.

Definition

• Vitamins are historically classified as either water-soluble or lipid-soluble.
• Water-soluble vitamins act as precursors for coenzymes, relevant to specific body reactions.

Vitamin C

• Vitamin C is L-Ascorbic Acid (antiscorbutic vitamin).
• Sources include fruits (citrus, melon, strawberries, guava) and vegetables (green leafy, tomatoes, potatoes). Animal sources include liver and adrenal glands.
• Functions:
  • Essential for collagen production. Procollagen (a protein containing proline and lysine) is converted into collagen by ascorbic acid.
  • Hydroxylation of proline and lysine in procollagen are aided by vitamin C
  • Acts as a reducing agent for hydroxylase enzyme.
  • Plays a role in oxidation-reduction reactions, acting as a hydrogen transport agent.
• Anti-cancer properties: High doses may inhibit carcinogenic N-nitroso compounds formed during cooking and digestion.

Deficiency (Scurvy)

• A deficiency of vitamin C can result in scurvy.
• Scurvy is characterized by:
  • Behavioral and emotional disturbances.
  • General weakness resulting from decreased carnitine and fatty acid oxidation.
  • Manifestations: bleeding into gums, muscles, joints, kidneys, and gastrointestinal tract; bone lesions, gum necrosis, delayed wound healing, and easy bruising due to increased capillary fragility.

Vitamin B-Complex

• Several chemical molecules are grouped together as vitamin B.
• Key members include: Thiamin (B1), Riboflavin (B2), Niacin (PPF), Pyridoxine (B6), Pantothenic acid, Biotin (H), and Vitamin B12.

Thiamin (Vitamin B1)

• Sources: Seeds (peas, beans) and animal products (liver, eggs, milk).
• Active form: Thiamin pyrophosphate (TPP)
• Functions of TPP : Essential coenzyme affecting pyruvate dehydrogenase, α-ketoglutarate dehydrogenase, and transketolase enzymes. Important for optimal growth in infants and children and nerve conduction and nerve membrane structure.
• Deficiency (Beriberi):
  • Biochemical changes: Accumulation of pyruvic acid and lactic acid in the blood, accumulation of pentose sugars in red blood cells.
  • Manifestations (Wet): Extensive edema, congestive heart failure.
  • Manifestations (Dry): Polyneuritis, hyperesthesia, muscle wasting, and loss of weight. Severe thiamine deficiency can lead to Wernicke's disease (neurological degeneration, ocular disturbances (ataxia), and Korsakoff's syndrome (memory issues, psychosis).

Riboflavin (Vitamin B2)

• Sources: Abundant in liver, yeast, whole grains, and milk.
• Active forms: Flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN)
• Functions: Affecting only dehydrogenase enzyme.
• Deficiency: Ocular disturbances (photophobia, corneal vascularization), mouth (red lips, angular stomatitis, glossitis, cheilosis), and skin conditions (seborrheic dermatitis).

Niacin (Vitamin B3)

• Sources: Whole grains, cereals, yeast, milk, and leafy green vegetables, meat. (Corn contains little niacin and tryptophan).
• Conversion from Tryptophan: Niacin can be made from tryptophan (an amino acid); 60 mg tryptophan can be converted to 1 mg niacin. The coenzyme required is pyridoxine (B6).
• Functions: Essential for forming coenzymes NAD+, NADP+, and NMN, crucial for oxidation-reduction reactions needing dehydrogenase enzymes.
• Deficiency (Pellagra): Manifestations include dermatitis (dry, rough, scaly skin), diarrhea (often severe), dementia (cognitive impairment), and even death in severe cases.

Pyridoxine (Vitamin B6)

• Sources: Yeast, rice polishing, germinal portion of various seeds, animal products (egg yolks), royal jelly.
• Functions: Affecting aminotransferase AST, ALT, and gamma-aminolevulinic acid synthase enzymes
• Deficiency: Stomatitis (cracking or scaling lips around mouth), growth retardation, convulsions, demyelination of peripheral nerves, and microcytic hypochromic anemia.

Pantothenic Acid (Vitamin B5)

• Sources: Abundant in animal products (meat, liver, kidney), and plant products (legumes, wheat, rice), royal jelly is the richest source.
• Functions: Affecting fatty acid synthase, fatty acyl CoA synthase, pyruvate dehydrogenase, and α-ketoglutarate dehydrogenase enzymes.
• Important for the synthesis of coenzyme A. An active participant in the extramitochondrial pathway synthesis of fatty acids.
• Deficiency may cause headaches, fatigue, irritability, intestinal disturbances, vomiting, insomnia, burning feet syndrome, stomach pains, and numbness in hands and feet.

Biotin (Vitamin H or Coenzyme R)

• Sources: Synthesized by intestinal bacteria, found in egg yolks, animal tissues, tomatoes, and yeast.
• Functions: A coenzyme for carboxylase enzymes that catalyze carboxylation reactions, such as pyruvate carboxylase, acetyl-CoA carboxylase, and propionyl-CoA carboxylase.
• Deficiency: Can result in dermatitis, muscle pain, loss of muscular control, pallor, alopecia, hallucinations, depression, immune deficiency disease, and growth retardation.

Vitamin B12 (Cyanocobalamin)

• Sources: Meat, eggs, milk, and milk products (absent in vegetables).

• Affecting enzymes: Homocysteine methyltransferase and methylmalonyl-CoA mutase.

• Absorption: Absorbed in the ileum after combining with intrinsic factor (IF).

• Deficiency: Caused by decreased intake (vegetarians), atrophy of gastric mucosa (leading to pernicious anemia), and antibodies to gastric parietal cells.

• Causes: Decreased intake (vegetarians), atrophy of gastric mucosa (pernicious anemia), presence of antibodies and impaired absorption.

• Manifestations: Megaloblastic anemia (macrocytic and hyperchromic, due to abnormal DNA replication), neurological manifestations (subacute combined degeneration of the spinal cord, peripheral neuritis), and increased methylmalonic acid excretion in urine.

Folic Acid (Vitamin B9)

• Sources: Leafy vegetables, liver, kidney, and yeast.
• Physiological Functions: Tetrahydrofolic acid (H4 folate). Involved in carbon group transfers.
• Deficiency:
  • Pancytopenia (all blood cell types affected): megaloblastic anemia resulting from folate deficiency and B12 deficiency.
  • Impaired growth during deficiency.