Vitamin A

This is a fat-soluble vitamin essential for vision, immune function, and cell growth. It exists in two primary forms: preformed vitamin A (retinol) found in animal products and provitamin A carotenoids (such as beta-carotene) found in plant-based foods.

Vitamin A RDA (Recommended Dietary Allowance):

• Men: 900 mcg/day (3,000 IU)
• Women: 700 mcg/day (2,333 IU)
• Pregnant women: 770 mcg/day (2,567 IU)
• Breastfeeding women: 1,300 mcg/day (4,333 IU)

ODA (Optimal Daily Allowance):

• 1,500-3,000 mcg/day (varies based on individual needs and health conditions)

Found in:

• Liver (beef, chicken)
• Fish (salmon, mackerel, tuna)
• Dairy products (cheese, butter, milk, eggs)
• Orange and yellow vegetables (carrots, sweet potatoes, pumpkin, butternut squash)
• Leafy greens (spinach, kale)
• Fruits (mangoes, apricots, cantaloupe)

Helps with:

• Maintaining healthy vision and preventing night blindness
• Supporting immune function and reducing infection risk
• Promoting healthy skin and cell growth
• Aiding in reproductive health
• Functioning as an antioxidant (beta-carotene form)

Insufficient doses:

• Night blindness and vision deterioration
• Increased susceptibility to infections
• Dry, scaly skin and delayed wound healing
• Growth retardation in children
• Impaired reproduction

Excessive doses:

• Toxicity (hypervitaminosis A) symptoms:
  • Nausea, dizziness, and headaches
  • Liver damage
  • Bone pain and increased fracture risk
  • Birth defects if consumed in excessive amounts during pregnancy
• Beta-carotene excess may cause harmless skin yellowing (carotenemia)

Types of Vitamin A:

• Retinol – Active form found in animal products
• Retinal – Essential for vision
• Retinoic acid – Important for skin and cell development
• Beta-carotene – A provitamin A carotenoid from plant sources that the body converts into active vitamin A

Interactions (synergy and anti):

• Synergy:
  • Works with zinc for proper vitamin A transport and absorption
  • Vitamin D and K2 help balance this vitamin’s role in bone health
  • Fats enhance its absorption (since it’s fat-soluble)
  • Vitamin E protects it from oxidation
• Antagonistic interactions:
  • Excess intake can interfere with vitamin D and K absorption, potentially leading to bone issues
  • Alcohol increases the risk of liver toxicity when combined with high doses of vitamin A
  • High doses of iron can reduce the levels of this vitamin