Biomolecules (Vitamins)

Vitamins

Vitamins are organic compounds that are essential for normal growth and nutrition and are required in small quantities in the diet because they cannot be synthesized by the body or synthesized in sufficient quantities. They act as coenzymes or cofactors, playing vital roles in various metabolic processes.

Classification Of Vitamins

Vitamins are primarily classified into two groups based on their solubility in water or fat:

1. Fat-Soluble Vitamins:

These vitamins dissolve in fats and oils. They can be stored in the body's fatty tissues and the liver. Because they can accumulate, excessive intake can be toxic.

• Vitamin A (Retinol):
  • Functions: Essential for vision (component of rhodopsin in the retina), cell growth and differentiation, immune function, and reproduction.
  • Deficiency: Night blindness, xerophthalmia (dry eyes), impaired immunity.
  • Sources: Liver, egg yolk, dairy products, cod liver oil, yellow and orange fruits and vegetables (as beta-carotene, a precursor).
• Vitamin D (Calciferol):
  • Functions: Crucial for calcium and phosphorus absorption, bone health, immune function, and cell growth. The body can synthesize vitamin D when exposed to sunlight.
  • Deficiency: Rickets (in children), osteomalacia (in adults), osteoporosis.
  • Sources: Fatty fish, fortified milk and cereals, egg yolk, sunlight exposure.
• Vitamin E (Tocopherol):
  • Functions: Acts as an antioxidant, protecting cell membranes from oxidative damage. It also plays a role in immune function and cell signaling.
  • Deficiency: Rare, but can cause neurological problems, muscle weakness, and vision issues.
  • Sources: Vegetable oils, nuts, seeds, leafy green vegetables.
• Vitamin K (Phylloquinone and Menaquinones):
  • Functions: Essential for blood clotting (synthesis of clotting factors) and bone metabolism.
  • Deficiency: Impaired blood clotting, leading to excessive bleeding.
  • Sources: Leafy green vegetables (kale, spinach), broccoli, Brussels sprouts, vegetable oils. Gut bacteria also synthesize some vitamin K.

2. Water-Soluble Vitamins:

These vitamins dissolve in water and are not stored in the body to a significant extent. They are generally excreted in urine, so regular intake is necessary. Toxicity is less common compared to fat-soluble vitamins.

• Vitamin C (Ascorbic Acid):
  • Functions: Acts as an antioxidant, essential for collagen synthesis, wound healing, immune function, and iron absorption.
  • Deficiency: Scurvy (fatigue, bleeding gums, poor wound healing).
  • Sources: Citrus fruits, berries, tomatoes, bell peppers, green leafy vegetables.
• B Vitamins (Complex): These are a group of eight water-soluble vitamins that often work together in metabolic processes, particularly in energy production.
  • Vitamin B1 (Thiamine):
    • Functions: Crucial for carbohydrate metabolism, nerve function.
    • Deficiency: Beriberi (neurological and cardiovascular problems).
    • Sources: Whole grains, pork, legumes, nuts.
  • Vitamin B2 (Riboflavin):
    • Functions: Involved in energy metabolism, cell growth, and vision.
    • Deficiency: Ariboflavinosis (cracks at corners of mouth, sore throat).
    • Sources: Dairy products, lean meats, eggs, leafy green vegetables.
  • Vitamin B3 (Niacin):
    • Functions: Involved in energy metabolism, DNA repair, and synthesis.
    • Deficiency: Pellagra (dermatitis, diarrhea, dementia).
    • Sources: Meat, poultry, fish, peanuts, whole grains.
  • Vitamin B5 (Pantothenic Acid):
    • Functions: Essential for the synthesis of coenzyme A (CoA), involved in energy metabolism and synthesis of fatty acids and cholesterol.
    • Deficiency: Rare, but can cause fatigue, insomnia, and gastrointestinal issues.
    • Sources: Widely distributed in foods (meat, vegetables, grains, dairy).
  • Vitamin B6 (Pyridoxine):
    • Functions: Involved in amino acid metabolism, neurotransmitter synthesis, and red blood cell formation.
    • Deficiency: Anemia, neurological problems.
    • Sources: Meat, poultry, fish, whole grains, bananas, potatoes.
  • Vitamin B7 (Biotin):
    • Functions: Involved in metabolism of carbohydrates, fats, and proteins. Essential for healthy hair, skin, and nails.
    • Deficiency: Rare, but can cause hair loss, skin rash.
    • Sources: Egg yolk, liver, nuts, soybeans, cauliflower. Gut bacteria also produce biotin.
  • Vitamin B9 (Folate/Folic Acid):
    • Functions: Crucial for DNA synthesis and repair, cell division, and red blood cell formation. Essential during pregnancy for preventing neural tube defects in the fetus.
    • Deficiency: Megaloblastic anemia, neural tube defects.
    • Sources: Leafy green vegetables, legumes, liver, fortified cereals.
  • Vitamin B12 (Cobalamin):
    • Functions: Essential for DNA synthesis, red blood cell formation, and neurological function. It requires intrinsic factor for absorption in the small intestine.
    • Deficiency: Pernicious anemia, neurological damage.
    • Sources: Primarily animal products (meat, fish, poultry, dairy, eggs).