Biochemistry 1 (PHB231) - Vitamins

Biochemistry 1 (PHB231) - Vitamins

• Vitamins are a group of essential nutrients, categorized as either fat-soluble or water-soluble.

• Macronutrients are needed in larger quantities and are a source of energy. Micronutrients, including vitamins and minerals, are equally important but are consumed in smaller amounts and are not a source of energy.

Classifications of Vitamins

• Fat-soluble vitamins include Vitamins A, D, E, and K.
• Water-soluble vitamins include Vitamins B and C.

Fat-Soluble Vitamins

Vitamin A

• Vitamin A is grouped as unsaturated nutritional organic compounds, including retinol, retinal, retinoic acid, and carotenoids (beta carotene).
• Functions: Retinol supports reproduction; retinal is involved in vision; retinoic acid supports growth; beta-carotene acts as an antioxidant.
• Deficiency: Xerophthalmia (dry eyes), keratinization, decreased mucosal immunity.

Vitamin D

• Obtained by irradiating provitamin D with ultraviolet light.
• Responsible for intestinal absorption of calcium, iron, and magnesium.
• Available in two forms: Vitamin D3 (cholecalciferol) and Vitamin D2 (ergocalciferol).
• Mechanism: Carried to the liver, converted into calcidiol (prohormone); in kidneys, calcidiol is converted to calcitriol (biologically active form); released into circulation; transported to body organs through binding with Vitamin D-binding protein. -Functions: A steroid hormone; facilitates calcium absorption from the intestine; maintains calcium homeostasis.
• Deficiency: Rickets (bones fail to calcify normally, causing growth retardation and skeletal abnormalities); Osteoporosis (lack of calcium resulting in porous and brittle bones).

Vitamin E

• A naturally occurring antioxidant, also known as tocopherols.
• Known for its anti-aging properties.
• Mechanism: Free radicals (superoxide, hydroxyl ions, nitric oxide) contain unpaired electrons; antioxidants (like Vitamin E) bind with free radicals, neutralizing unpaired electrons; Vitamin E binds to O2⁻ to form tocopherylquinone.
• Functions: Antioxidant; protects cell membrane from reactive oxygen species (ROS) and other polyunsaturated fatty acids like Vitamin A.
• Deficiency: Can lead to reproductive dysfunction, hemolytic anemia, and nerve damage.

Vitamin K

• Also known as anti-hemorrhagic vitamin.
• Naturally produced by bacteria in the intestine.
• Essential for producing a type of protein (prothrombin) vital for blood clotting.
• Forms: Phylloquinone and Menaquinones (MK-n).
• Functions: Necessary for formation of several blood-clotting factors in the liver; deficiency leads to bleeding disorders.
• Deficiency: May be caused by antibiotics; hemorrhaging; malabsorption.

Water-Soluble Vitamins

Vitamin B Complex

• Group of B vitamins include B1 (thiamine), B2( Riboflavin), B3 (niacin), B6, B9 (folic acid), and B12.
• Various functions in the body related to nerve and muscle function, carbohydrate, protein, and fat metabolism, DNA & RNA synthesis, RBCs and WBCs formation.
• Specific deficiencies lead to specific symptoms for each vitamin.

Vitamin C

• Ascorbic acid.
• Functions as a cofactor, enzyme complement and a powerful antioxidant.
• Stabilizes vitamin E and folic acid, and enhances iron absorption.
• Mechanism: Scavenges free radicals and reactive oxygen molecules; prevents the formation of carcinogens from precursor compounds.
• Functions: Coenzyme for collagen formation; involved in carnitine's role in fatty acid oxidation; necessary for conversions of amino acids to neurotransmitters; assists in hormone production; antihistaminic properties for congestion relief.
• Deficiency: Scurvy (bleeding gums, loosened teeth, pinpoint hemorrhages, bone fragility, poor wound healing, frequent infections).

Explore the essential nutrients known as vitamins in this quiz from Biochemistry 1. Discover the differences between fat-soluble and water-soluble vitamins and their classifications. Learn about the functions, sources, and deficiencies related to key vitamins.