Vitamin A(va)

Deficiency and Toxicity

• Deficiency Symptoms
   
  Mild deficiency may cause night blindness, dry skin, and increased susceptibility to infections. Severe, long-term deficiency can lead to xerophthalmia (dry eyes progressing to corneal ulceration and blindness), growth retardation in children, and impaired reproductive function. Deficiency is more common in regions with limited access to animal products and diverse fruits/vegetables.
• Toxicity
   
  Unlike water-soluble vitamins, excess vitamin A accumulates in the liver, leading to hypervitaminosis A. Acute toxicity (from very high doses in a short time) can cause nausea, vomiting, headache, and blurred vision. Chronic toxicity (from long-term high-dose supplementation) may result in bone pain, hair loss, liver damage, and birth defects in pregnant women. Provitamin A carotenoids have low toxicity risk, as the body limits their conversion to retinol; excess intake may only cause harmless skin discoloration (carotenemia).