Vitamins and Their Functions

Vitamins

• Organic compounds that are essential in small amounts for bodily processes.
• Vitamins do not provide energy, rather they help the body use energy from carbohydrates, fats, and proteins.
• Classified by their solubility:
  • Fat-soluble: Vitamins A, D, E, and K
  • Water-soluble: Vitamin B Complex (B1, B2 B12, folate, niacin, B6, biotin, pantothenic acid) and vitamin C (ascorbic acid)

Vitamin A

• Found in two forms:
  • Preformed: Retinol (active form)
  • Provitamin: Carotenoids (inactive form found in plants, such as beta-carotene)
• Plays a vital role in:
  • Vision
  • Bone growth
  • Reproduction
  • Cell division
• Regulates the immune system, helping to fight infections
• Provitamin A functions as an antioxidant, protecting cells from free radicals
• Involved in:
  • Sex hormone production
  • Growth processes
  • Protein synthesis
  • Bone and teeth growth
  • Red blood cell production
  • Skin and cellular health
• Food Sources:
  • Animal sources: Eggs, meat, fortified milk, cheese, cream, liver, kidney, cod, fish oil
  • Plant sources: Orange and yellow vegetables and fruits, broccoli, spinach, dark green leafy vegetables

Vitamin A Deficiency

• Night blindness
• Dry skin
• Increased susceptibility to infections
• Avitaminosis A: Can lead to blindness or xerophthalmia (dry mucous membranes of the eye)
• Leading cause of blindness worldwide
• Risks: People in impoverished areas, elderly individuals, those with liver disease or AIDS

Vitamin A Recommended Daily Allowance (RDA)

• Varies based on age and life stage (e.g., infants, children, pregnant women, lactating women)

Vitamin A Toxicity (Hypervitaminosis A)

• Excessive intake of vitamin A supplements can be dangerous
• Symptoms: Birth defects, hair loss, dry skin, headaches, nausea, dry mucous membranes, liver damage, bone and joint pain

Vitamin D

• Found in two forms:
  • D2 (ergocalciferol): Formed in plants from exposure to ultraviolet light
  • D3 (cholecalciferol): Formed in humans from cholesterol in the skin upon exposure to ultraviolet light
• Both D2 and D3 are equally effective in human nutrition
• Heat-stable and not easily oxidized, making it stable during storage, processing, and cooking.
• Sun Exposure:
  • Recommended exposure to sunlight 2-3 times a week to get 30-50 percent of needed vitamin D
  • 10-15 minutes of sun exposure is needed to complete the vitamin D synthesis process
  • Dark-skinned individuals require longer exposure to the sun than those with light skin

Vitamin D Functions

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