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INFORMATION ON VITAMIN A
Vitamin A exists as preformed vitamin A (retinol, retinyl esters) from animal sources and provitamin A carotenoids (beta-carotene) from plant sources. It is fat-soluble and essential for vision, immune defense, and cellular differentiation.
Functions:
- Supports retinal function and rhodopsin synthesis for vision
- Maintains epithelial tissue in skin, gut, and respiratory tract
- Plays a role in gene expression and cell differentiation
- Functions as an antioxidant
POPULAR USE & PUBLISHED BENEFITS bbbb
- Vision health, especially night vision and retinal function
- Immune system function and infection resistance
- Skin health and epithelial tissue integrity
- Reproductive health and fetal development
- Antioxidant protection (via carotenoids)
- Cellular growth and differentiation
WHOLE FOODS
Animal Sources (preformed vitamin A):
- Liver, fish liver oils, eggs, butter, dairy
Plant-Based Sources (provitamin A / beta-carotene):
- Carrots, sweet potatoes, pumpkin, spinach, kale, red peppers, mango
RECOMMENDED USE
Synergistic Nutrients:
- Zinc: Required for vitamin A transport and retinal function
- Vitamin E: Protects vitamin A from oxidation
- Omega-3 fatty acids: Support retinal health
Typical Dosages:
- Maintenance: 1500–3000 IU/day (retinol activity equivalents)
- Functional support (skin, immunity, vision): 3000–9900 IU/day
- Therapeutic (dermatology, night vision): 9900–33000 IU/day under supervision
- Upper safe limit: 9990 IU/day preformed vitamin A
- Excess preformed vitamin A can be toxic (hypervitaminosis A), causing liver toxicity, hair loss, or bone issues
- Pregnant women should avoid high-dose retinol supplements without medical supervision
VITAMIN A
- NIH Fact Sheet on Vitamin A: ods.od.nih.gov
- Linus Pauling Institute: lpi.oregonstate.edu
- Sommer A. N Engl J Med (2008) – Vitamin A and infection prevention
- Tang G et al. Am J Clin Nutr (2009) – Carotenoids and conversion to vitamin A
- Ross AC. J Nutr (2012) – Vitamin A: metabolism and health effects