Vitamin A Deficiency: A Concept-First Explanation
Think of vitamin A as the body's night-vision battery and its skin-and-mucosa repair kit. You don't see it, you don't feel it, but when it runs low, the first sign often comes at dusk — things go blurry when the light fades. That's not a random symptom; it's the body telling you that a specific chemical, retinal, which your eyes need to detect dim light, isn't being made fast enough.
Vitamin A is a fat-soluble vitamin. That means your body stores it in the liver and uses it slowly, so a deficiency doesn't happen overnight. It builds up over weeks or months when your diet lacks foods that provide either preformed vitamin A (from animal sources like liver, eggs, milk) or provitamin A carotenoids (from orange and green vegetables like carrots, spinach, papaya — beta-carotene is the most famous one, which your body converts into vitamin A).
What exactly goes wrong?
The deficiency hits three main systems in the body, and they follow a predictable order.
The eyes are hit first and hardest. The earliest stage is night blindness — you can see fine in bright light, but struggle to see in dim light or darkness. If the deficiency continues, the surface of the eye (the cornea) dries out, a condition called xerophthalmia. In severe, untreated cases, the cornea softens and ulcers form, leading to irreversible blindness. This is the leading cause of preventable childhood blindness worldwide.
The immune system weakens. Vitamin A is essential for maintaining the integrity of mucous membranes — the linings of your respiratory tract, gut, and urinary tract. Without it, these barriers become brittle and leaky, making it easier for bacteria and viruses to enter. A child with vitamin A deficiency gets more frequent and more severe infections, especially measles and diarrhoeal diseases.
The skin and growth suffer. The skin becomes dry, rough, and bumpy — a condition called follicular hyperkeratosis, where hair follicles get clogged with keratin. In children, growth slows down, and bone development can be impaired.
Vitamin A deficiency is not a rare disease. It is a public health problem in many developing countries, especially where diets are heavily based on white rice, maize, or cassava with little variety in vegetables, fruits, or animal products. Pregnant women and young children are the most vulnerable groups.
Why should a commerce or humanities student care? …