Vitamins: Definition, Classification, and Functions

Definition and Function

• A vitamin is a type of nutrient that is required in small amounts for various bodily functions.
• Vitamins are organic compounds that cannot be produced by the human body and must be obtained through the diet or supplements.

Classification

• Vitamins can be classified into two main categories:
  • Fat-soluble vitamins: A, D, E, and K
  • Water-soluble vitamins: B and C

Fat-Soluble Vitamins

• Vitamin A:
  • Important for vision, immune function, and skin health
  • Food sources: sweet potatoes, carrots, dark leafy greens, and liver
• Vitamin D:
  • Essential for bone health and immune function
  • Food sources: fatty fish, fortified dairy products, and sunlight exposure
• Vitamin E:
  • Acts as an antioxidant, protecting cells from damage
  • Food sources: nuts, seeds, and vegetable oils
• Vitamin K:
  • Necessary for blood clotting and bone health
  • Food sources: leafy greens, such as spinach and kale, and fermented foods

Water-Soluble Vitamins

• Vitamin B:
  • Complex of several B vitamins, including thiamin, riboflavin, and niacin
  • Important for energy metabolism and nerve function
  • Food sources: whole grains, lean meats, and fish
• Vitamin C:
  • Important for immune function and collagen production
  • Food sources: citrus fruits, strawberries, and bell peppers

Deficiency and Toxicity

• Vitamin deficiency can occur due to inadequate diet, malabsorption, or increased demand.
• Vitamin toxicity can occur due to excessive intake of fat-soluble vitamins, leading to adverse health effects.

Recommended Dietary Allowance (RDA)

• The RDA is the daily intake of vitamins and other nutrients that meets the nutritional needs of 97-98% of healthy individuals.
• RDAs vary by age, sex, and other factors, and are used to guide dietary recommendations.