Vitamins

Vitamins are organic substances found in small amounts in food, essential for growth, metabolic functions, and preventing deficiency diseases. They do not provide calories but aid in releasing energy from carbohydrates, fats, and proteins.

Classification of Vitamins

1. Fat-Soluble Vitamins: A, D, E, and K (require fat for absorption and can be stored in the body).
2. Water-Soluble Vitamins: B-group and Vitamin C (not stored in the body, require regular intake).

Fat-Soluble Vitamins

Vitamin A (Retinol / Carotenoids)

• Forms: Retinol, Retinal, Retinoic acid (retinoids).
• Sources: Animal foods (liver, egg yolk, butter, milk, cheese) and carotenoids in plant foods (carrots, spinach, broccoli, pumpkin, mangoes).
• Functions: Supports vision (dark adaptation), growth, skin health, gene regulation, and immune function. Essential during early pregnancy for embryo development.
• Deficiency: Night blindness, skin issues, growth retardation. Excessive intake leads to hypervitaminosis A, but β-carotene poses no such risk.

Vitamin D (Calciferol)

• Sources:
  • Sunlight: Skin synthesizes vitamin D from 7-dehydrocholesterol under UVB rays.
  • Foods: Liver, egg yolk, milk, butter, fish liver oils, and mushrooms.
• Functions: Enhances calcium and phosphorus absorption. Promotes bone mineralization and growth. Used to treat rickets and osteoporosis.
• Deficiency:
  • In children: Rickets, affecting bone development.
  • In adults: Osteomalacia and increased risk of osteoporosis.

Vitamin E (α-Tocopherol)

• Function: Acts as a powerful antioxidant, protecting cell membranes, proteins, fatty acids, and DNA. Works with selenium to prevent tissue breakdown.
• Sources: Vegetable oils (wheat germ, sunflower, rapeseed), leafy greens (spinach, chard), nuts (almonds, peanuts), avocados, sunflower seeds, and fruits (mango, kiwifruit).
• Deficiency: Rare; can cause red blood cell breakdown and nerve damage.
• Excess: Generally safe, stored in the liver.

Vitamin K (Phylloquinone)

• Function: Essential for blood clotting by aiding prothrombin formation in the liver.
• Sources: Green leafy vegetables (spinach, cabbage), vegetable oils (soybean, canola, olive).
• Deficiency: Prolonged clotting time, excessive bleeding (hemorrhagic disease). Newborns lack vitamin K reserves, so supplementation is common in hospitals.

Water-Soluble Vitamins

Water-soluble vitamins include ascorbic acid (vitamin C) and the B-complex vitamins. They are quickly absorbed by the body, and excess amounts are excreted in urine. Therefore, adequate daily intake is essential. Some of these vitamins can be partially lost during cooking.

Vitamin B-Complex

The six essential B-complex vitamins are thiamin, riboflavin, niacin, pyridoxine, folic acid, and vitamin B12. A diet sufficient in these vitamins typically covers other B-complex members as well.

1. Vitamin B1 (Thiamin)

• Function: Energy metabolism, nerve, muscle, and heart function.
• Sources: Liver, fish, meat, whole grains, legumes, nuts, leafy greens, soymilk.
• Deficiency: Beriberi (nervous and cardiovascular damage) and Wernicke-Korsakoff syndrome.

2. Vitamin B2 (Riboflavin)

• Function: Energy release from carbohydrates, fats, and proteins; supports growth and vision.
• Sources: Milk, liver, eggs, whole grains, dark leafy greens, pulses.
• Deficiency: Photophobia, rough eyelids, skin changes around the mouth and nose.

3. Vitamin B3 (Niacin)

• Function: Coenzyme in energy transfer, neurological protection.
• Sources: Liver, fish, meat, whole grains, legumes, nuts, avocados, milk.
• Deficiency: Pellagra, characterized by dermatitis, diarrhea, dementia, and death.

4. Vitamin B5 (Pantothenic Acid)

• Function: Fatty acid synthesis, tissue repair, energy metabolism.
• Sources: Liver, chicken, egg yolk, milk, whole grains, tomatoes, broccoli.
• Deficiency: Rare; symptoms include fatigue, nausea, headaches, and “burning feet” syndrome.

5. Vitamin B6 (Pyridoxine)

• Function: Amino acid metabolism, neurotransmitter synthesis, red blood cell formation.
• Sources: Chicken, fish, nuts, chickpeas, whole grains, bananas, potatoes.
• Deficiency: Rare; usually occurs with deficiencies in other B vitamins.

6. Vitamin B7 (Biotin/Vitamin H)

• Function: Coenzyme for energy metabolism, supports hair, skin, and nail health.
• Sources: Eggs, milk, nuts, soybeans, cereals, liver, kidney.
• Deficiency: Fatigue, nausea, neurological issues, poor skin and hair quality.

7. Vitamin B9 (Folate)

• Function: Coenzyme for carbon transfer, nucleic acid synthesis, cell growth.
• Sources: Leafy greens, legumes, wheat germ, peanuts, oranges, strawberries.
• Deficiency: Megaloblastic anemia, neural tube defects in fetuses, digestive issues.

8. Vitamin B12 (Cobalamin)

• Function: Coenzyme for amino acid metabolism, nerve protection, red blood cell formation.
• Sources: Animal-based foods (meat, fish, eggs, dairy), fortified plant-based products.
• Deficiency: Megaloblastic anemia, neurological damage, fatigue.