Vitamin A

Everything About Vitamin A: Roles, Benefits, Deficiency, and More

1. What Is Vitamin A? Vitamin A is a fat-soluble vitamin essential for many bodily functions, including vision, immune response, skin health, reproduction, and cellular communication. It exists in two primary forms:

  • Preformed vitamin A (retinol, retinal, retinoic acid) – found in animal products like liver, dairy, and fish.
  • Provitamin A carotenoids (beta-carotene, alpha-carotene) – found in plant-based foods like carrots, sweet potatoes, and spinach.



2. Functions of Vitamin A by Body System

  • Eyes/Vision:
  • Essential for night vision (part of rhodopsin in the retina).
  • Prevents xerophthalmia and age-related macular degeneration.
  • Immune System:
  • Strengthens mucosal barriers (lungs, GI tract).
  • Enhances white blood cell function and cytokine response.
  • Plays a role in immune tolerance and reduces risk of infection.
  • Skin and Epithelial Health:
  • Supports turnover and repair of skin cells.
  • Commonly used in acne (retinoids), psoriasis, and keratosis pilaris.
  • Reproductive Health:
  • Supports healthy sperm and egg development.
  • Involved in fetal development (especially eyes, lungs, and heart).
  • Endocrine and Hormonal System:
  • Works with thyroid hormone and vitamin D at the nuclear receptor level.
  • Mood and Neurological Health:
  • Involved in dopaminergic and serotonergic neurotransmission.
  • Deficiency may be linked to depression, cognitive decline.
  • Cancer Prevention:
  • Antioxidant effects (especially from carotenoids).
  • May reduce risk of some cancers (lung, prostate, cervical) in deficient populations.
  • Cellular Level:
  • Regulates gene expression and cell differentiation.
  • Crucial for stem cell function and tissue regeneration.



3. Symptoms of Deficiency

  • Night blindness
  • Dry eyes or corneal ulcers
  • Recurrent infections
  • Rough, dry skin or eczema
  • Poor wound healing
  • Fatigue
  • Infertility
  • Bitot’s spots (foamy patches on the eye)

Who’s at Risk?

  • People with fat malabsorption (IBD, celiac, pancreatitis)
  • Low intake of animal products or orange/yellow vegetables
  • Alcoholics
  • Children in developing countries



4. Signs of Excess (Toxicity)

  • Headache, nausea
  • Blurred vision
  • Liver damage
  • Birth defects (in pregnancy)
  • Bone pain or fractures
  • Peeling skin

Note: Carotenoids (like beta-carotene) do not cause toxicity but can cause orange skin (carotenemia).



5. Testing and Optimal Levels

  • Serum retinol is commonly used; values below 20 mcg/dL suggest deficiency.
  • Consider testing if:
  • Unexplained skin conditions
  • Vision issues
  • Frequent infections
  • Malabsorption disorders



6. Best Food Sources

  • Preformed A: Beef liver, cod liver oil, egg yolks, butter, cheese
  • Provitamin A carotenoids: Carrots, pumpkin, sweet potato, kale, spinach, red bell pepper, mango



7. Supplementation

  • Retinyl palmitate (animal-based)
  • Beta-carotene (plant-based, safer but less potent)
  • RDA: 900 mcg/day for men, 700 mcg/day for women
  • Upper limit: 3,000 mcg/day (preformed vitamin A only)

Special Considerations:

  • Avoid excess in pregnancy (teratogenic)
  • Balance with vitamin D, K2, and zinc for proper utilization



8. Vitamin A in Skin and Hair Disorders

  • Acne (topical and oral retinoids)
  • Psoriasis (retinoid therapy)
  • Hyperkeratosis
  • Alopecia support (through cell turnover and scalp health)



9. Vitamin A and the Microbiome

  • Supports mucosal immunity and gut barrier integrity
  • Interacts with dendritic cells and immune signaling in the gut



10. Fun Facts

  • Polar bear liver contains toxic levels of vitamin A—don’t eat it!
  • Vitamin A deficiency is the leading cause of preventable blindness in children worldwide.
  • Retinoic acid is used in leukemia treatment (APL subtype).



11. Emerging Research

  • Use in immune modulation for autoimmune diseases
  • Role in brain development and neurodegeneration
  • Anticancer effects via gene regulation pathways



Conclusion Vitamin A is vital for vision, immunity, skin, hormones, and cellular health. Both deficiency and excess can cause serious problems. Prioritize a colorful, nutrient-rich diet and consider testing if symptoms suggest an imbalance. Supplement with care, especially during pregnancy or in liver disease.

Learn more