Understanding Vitamin A (Retinol): Normal vs Optimal Ranges

?What is Vitamin A (Retinol)?

Vitamin A (retinol) is a fat-soluble vitamin essential for vision (particularly night vision), immune function, cell growth and differentiation, and reproductive health. It comes preformed (retinol) from animal sources and as provitamin A carotenoids (beta-carotene) from plants, which are converted to retinol in the body. Serum retinol reflects liver vitamin A stores.

!Why It Matters

Vitamin A deficiency causes night blindness (early sign), increased susceptibility to infections, and — in severe deficiency — complete blindness (xerophthalmia) from corneal ulceration. It is the leading preventable cause of childhood blindness globally. Vitamin A toxicity (hypervitaminosis A) from excessive supplementation causes liver damage, headaches, bone abnormalities, and teratogenicity. The therapeutic window is narrower than for water-soluble vitamins.

Reference Ranges

Lab normal ranges may vary between laboratories. Optimal and longevity targets are based on research literature and should be interpreted with your physician.

Symptoms of Imbalance

• Deficiency: night blindness, dry eyes (xerophthalmia), rough dry skin, increased infections
• Toxicity: headache, nausea, hair loss, liver damage, birth defects in pregnancy

How to Improve Your Levels

• 1Eat vitamin A-rich animal foods: liver (most concentrated source), egg yolks, dairy, oily fish
• 2Eat beta-carotene-rich foods: carrots, sweet potato, spinach, pumpkin (less efficient conversion)
• 3Fat absorption is required for vitamin A — eat with fat
• 4Do not supplement high-dose vitamin A without monitoring serum levels

When to Test

Suspected deficiency (night blindness, chronic GI malabsorption); monitoring high-dose supplementation; pre-pregnancy assessment.

Related Biomarkers